U.S. patent application number 10/051364 was filed with the patent office on 2002-09-05 for apparatus and method for radial and angular or rotational analysis of images for shape content and matching.
Invention is credited to Crill, Rikk.
Application Number | 20020122595 10/051364 |
Document ID | / |
Family ID | 27609084 |
Filed Date | 2002-09-05 |
United States Patent
Application |
20020122595 |
Kind Code |
A1 |
Crill, Rikk |
September 5, 2002 |
Apparatus and method for radial and angular or rotational analysis
of images for shape content and matching
Abstract
A segmented radial spatial light modulator has an active optic
area comprising a plurality of radially extending active optic
modulators disposed at various angular orientations with respect to
a central axis. The segmented radial spatial light modulator is
used in separating and isolating portions of Fourier transform
optic patterns from images for characterization of images by shape
for recording, storing, retrieving, searching, and comparison to
other images for matches and near matches. The images can be
ghosted to increase optical power in the Fourier transform optic
pattern without adding new shape content and for grading
comparisons to other image shape characteristics for identifying
near matches in addition to matches.
Inventors: |
Crill, Rikk; (Longmont,
CO) |
Correspondence
Address: |
IP PATENTS
FAEGRE & BENSON LLP
1900 FIFTEENTH STREET
BOULDER
CO
80302
US
|
Family ID: |
27609084 |
Appl. No.: |
10/051364 |
Filed: |
January 18, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10051364 |
Jan 18, 2002 |
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09536426 |
Mar 27, 2000 |
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09536426 |
Mar 27, 2000 |
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09326362 |
Jun 4, 1999 |
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Current U.S.
Class: |
382/211 ;
707/E17.02 |
Current CPC
Class: |
G06K 9/522 20130101;
G06F 16/583 20190101; G02F 1/133362 20130101; G02F 2203/50
20130101; G06T 7/00 20130101; G02F 2203/12 20130101; G06V 10/431
20220101; G02F 1/13306 20130101; G06K 9/74 20130101; G02B 27/46
20130101; G06K 9/748 20130101; G06V 10/88 20220101; G06K 9/58
20130101; G02F 1/134309 20130101; G06V 10/92 20220101 |
Class at
Publication: |
382/211 |
International
Class: |
G06K 009/76 |
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed include:
1. A method of characterizing an image for shape content,
comprising: producing a Fourier transform optic pattern of the
image with light energy; spatial filtering the light energy from
the Fourier transform optic pattern by selecting light energy from
discrete portions of the Fourier transform optic pattern at a
plurality of angular orientations and separating such discrete
portions from other portions of Fourier transform optic pattern to
create a plurality of filtered patterns of light energy from those
discrete portions; detecting intensities of light energy as it is
distributed in the filtered patterns for the respective angular
orientations; and storing the intensities of light energy detected
in the filtered patterns along with the respective angular
orientations.
2. The method of claim 1, including: focusing the Fourier transform
optic pattern onto an active optic area of a spatial light
modulator; selectively activating portions of the spatial light
modulator at selected angular orientations to rotate plane of
polarization of the discrete portions of the light energy of the
Fourier transform optic pattern; separating light with rotated
plane of polarization from light without rotated plane of
polarization; and detecting the intensities of light that has
rotated plane of polarization.
3. The method of claim 2, including selectively activating portions
of the spatial light modulator at selected segments positioned at
different radial distances from an optic axis of the Fourier
transform optic pattern as well as in said angular
orientations.
4. The method of claim 2, including selectively activating portions
of the spatial light modulator to rotate plane of polarization of
light energy in the Fourier transform optic pattern that is
incident on selected sectors of the active optic area of the
spatial light modulator.
5. The method of claim 4, including selectively activating portions
of the spatial light modulator to rotate plane of polarization of
light energy in the Fourier transform optic pattern that is
incident on selected segments of the selected sectors.
6. The method of claim 1, including: producing a plurality of ghost
images around the image that is being characterized, each ghost
image having shape content that is substantially the same as the
image being characterized; and producing the Fourier transform
optic image from the ghost images along with the image being
characterized.
7. The method of claim 6, including producing the ghost images with
each ghost image having less light energy than the image being
characterized.
8. The method of claim 6, including replicating original pixels
that comprise the image being characterized and offsetting each
such replicated pixel from its corresponding original pixel by an
equal distance and angular orientation to the original pixel to
create a ghost image.
9. The method of claim 8, including dispersing the plurality of
ghost images in a symmetrical manner around the image being
characterized.
10. The method of claim 6, including: finding edges of the shape
content in the image being characterized an edge image of the shape
content; replicating original pixels that comprise the edge image;
and offsetting each such replicated pixel from its corresponding
original pixel by an equal distance and angular orientation to the
original pixel to create a ghost image.
11. The method of claim 10, replicating the pixels that comprise
the ghost image with less light energy than the corresponding
pixels of the edge image.
12. An optical image shape content analyzer, comprising: a Fourier
transform lens having a focal point in focal plane at a focal
distance; a spatial light filter comprising: (i) a filter spatial
light modulator that has an active optic area around a central axis
positioned in the focal plane of the Fourier transform lens with
the central axis coincident with the focal point, said active optic
area comprising discrete active optic components that are capable
of selective activation to selectively rotate or not rotate plane
of polarization of light incident at various angular orientations
in relation to the central axis; and (ii) a polarization analyzer
that is capable of separating light polarized in one plane from
light polarized in another plane; an image producing spatial light
modulator with an associated monochromatic light source, wherein
the image producing spatial light modulator is addressable to
produce an image in an optic pattern with light from the associated
monochromatic light source, said image producing spatial light
modulator being positioned to project such an image optic pattern
of monochromatic light through the Fourier transform lens to form a
Fourier transform optic pattern of the image optic pattern at the
focal plane of the Fourier transform lens; and a photodetector
positioned to receive light filtered by the spatial light filter,
said detector including an array of sensors that are capable of
detecting filtered patterns of light energy intensities in the
filtered light.
13. The optical image shape content characterizer of claim 12,
wherein the discrete active components are disposed in the active
optic area in a manner that extends radially outward at various
angular orientations in relation to the central axis.
14. The optical image shape content characterizer of claim 13,
wherein the discrete active components comprise individual sectors
of the active optic area.
15. The optical image shape content characterizer of claim 14,
wherein the discrete active components comprise individually
addressable segments of the sectors.
16. The optical image shape content characterizer of claim 15,
wherein the individually addressable segments are disposed radially
in relation to the central axis to form the active optic
sectors.
17. The optical image shape content characterizer of claim 13,
wherein the discrete active components comprise rectangular
components extending radially in relation to the central axis.
18. The optical image shape content characterizer of claim 13,
wherein the active optic area comprises a rectangular spatial light
modular array of active optic elements and the discrete active
components comprise active optic elements of a rectangular array of
such elements that are activatable in distance groups of such
elements that extend radially outward in relation to the central
axis.
19. A spatial light modulator, comprising an active optic area
around a central axis, said active optic area comprising a
plurality of active optic modulators that extend radially at
various angular orientations in relation to the central axis.
20. The spatial light modulator of claim 19, wherein each active
optic modulator includes a sector of the active optic area.
21. The spatial light modulator of claim 20, wherein each sector
comprises a plurality of individually addressable active optic
segments positioned to extend serially in one of said angular
orientations.
22. The spatial light modulator of claim 19, wherein each active
optic modulator is rectangular.
23. The spatial light modulator of claim 22, wherein each
rectangular active optic modulator comprises a plurality of
individually addressable active optic segments positioned to extend
serially in one of said angular orientations.
24. The spatial light modulator of claim 19, wherein the active
optic area includes a rectangular array of optic sensors and each
active optic modulator comprises a group of the optic sensors that
are actuateable together simultaneously to modulate light and that
together in the group are configured to form a composite of the
active optic elements extending radially in relation to the central
axis.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATION
[0001] This patent application is a continuation-in-part of U.S.
patent application Ser. No. 09/536,426, filed in the U.S. Patent
and Trademark Office on Mar. 27, 2000, which is a
continuation-in-part of Ser. No. 09/326,362, filed in the U.S.
Patent and Trademark Office on Jun. 4, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to spatial light modulators
and, more particularly, to a spatial light modulator with radially
oriented active light modulating sectors for radial and angular
analysis of beams of light, including Fourier transform optic
patterns, for uses such as characterizing, searching, matching or
identifying shape content of images.
[0004] 2. State of the Prior Art
[0005] There are situations in which useful information can be
derived from spatially dispersed portions of light beams. In
particular, when an image is being carried or propagated by a light
beam, it may be useful to gather and use or analyze information
from a particular portion of the image, such as from a particular
portion of a cross-section of a beam that is carrying an image.
[0006] For example, in my co-pending U.S. patent application, Ser.
No. 09/536,426, which is incorporated herein by reference, narrow,
radially oriented portions of a Fourier transform of an image are
captured, detected, and used to characterize and encode images by
shape for storage, searching, and retrieval. As explained therein,
such radially oriented, angularly or rationally spaced portions of
a Fourier transform of an image are captured sequentially by
positioning a rotating, opaque mask or wheel with a radially
oriented slit in the Fourier transform plane of a light beam
carrying the image after passing the light beam through a Fourier
transform lens and detecting the light that passes through the slit
at various angular orientations, i.e., degrees of rotation. The
light energy detected at each angular orientation is characteristic
of the portions of the image content that are generally linearly
aligned in the same angular orientation as the slit in the rotating
mask when the light energy is detected.
[0007] That system with the rotating, radially oriented, slit does
perform the task of characterizing and encoding images by shape
content of the images quite well and quite efficiently. However, it
still has several shortcomings. For example, resolution of spatial
frequency of an image at each angular orientation of the rotating
slit is not as good as some applications or uses of such a system
might require. Also, the spinning mask or wheel with an associated
drive mechanism, like all mechanical devices, has stability and
long term reliability issues, not to mention size and weight
requirements.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is a general object of this invention to
provide an improved apparatus and method for capturing and
recording optical information from portions of optical images.
[0009] A more specific object of this invention is to provide an
improved apparatus and method for spatial analysis of Fourier
transform optical patterns of images for shape content of such
images.
[0010] Another specific object of this invention is to provide an
improved apparatus and method for characterizing and encoding
images by shape content for storing, searching, comparing,
matching, or identifying images.
[0011] This and other objects, advantages, and novel features of
the invention shall be set forth in part in the description that
follows, and in part will become apparent to those skilled in the
art upon examination of the following description or may be learned
by the practice of the invention. The objects and the advantages
may be realized and attained by means of the instrumentalities and
in combinations particularly pointed out in the appended
claims.
[0012] To further achieve the foregoing objects, the apparatus of
this invention includes a spatial light modulator with a plurality
of addressable, active optic elements that extend radially at
various angular orientations in relation to an axis. The active
optic elements are preferably shaped to modulate portions of light
beams incident on discrete sectors of an active optic area on which
the beam of light can be focused. Therefore, active optic
modulators in the shape of individual sectors, i.e., essentially
wedge-shaped, are preferred, although other shapes are also
feasible and, in special circumstances, possibly even more
desirable, such as rectangular for better resolution or curved for
detection of curved shape content of an image. For better
resolution of spatial frequency of shape content, the radially
extending wedges or rectangles of the active optic area can be
comprised of individually addressable segments, which can be
activated separately or in groups, depending on the resolution
desires. Wedge-shaped sectors can comprise segments of smaller,
truncated wedge-shaped active optic elements or groups of sensors
in pixel arrays that, in composite, form such shapes. Rectangular
areas can also comprise smaller rectangular segments or composited
groups of sensors in pixel arrays to form such radially extending,
angularly spaced, active optic components or areas. For shape
content characterization of an image, an optic pattern that is a
Fourier transform of the image is focused on the active optic area,
and radially disposed portions of the Fourier transform optic
pattern at various angular orientations are selected and isolated
by the spatial light modulator for detection of shape content of
the image that is aligned with such angular orientations. The
intensities of light detected from such respective portions are
characteristic of such shape content and can be recorded, stored,
or used to compare with similarly analyzed shape content of other
images to find and identify matches or near matches of images with
such shape content. Optional image pre-processing to add ghost
images at various radial and angular relationships to the image and
at various light intensities can enhance detectability of shape
content and can enable near matching of images with similar shape
content.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate the preferred
embodiments of the present invention, and together with the
descriptions serve to explain the principles of the invention.
In the Drawings:
[0014] FIG. 1 is an isometric view of a segmented radial spatial
light modulation device according to this invention illustrated
with a beam of light focused on the light modulating components in
the active optic area of the device;
[0015] FIG. 2 is a front elevation view of the preferred light
modulating components in the active optic area of the segmented
radial spatial light modulator device of this invention in the
shape of segmented sectors that are oriented to extend radially at
various angular orientations in relation to a central axis;
[0016] FIG. 3 is an enlarged, front elevation view of one sector of
the active, light modulating components of the segmented radial
spatial light modulator device;
[0017] FIG. 4 is a cross-sectional view of a portion of an active
optic sector of a segmented radial spatial light modulator of the
present invention taken substantially along section line 4-4 of
FIG. 3;
[0018] FIG. 5 is a schematic diagram of an optical image
characterizer in which a segmented radial optical analyzer device
according to this invention is illustrated in an application for
characterizing and encoding optical images by shape content to
exemplify its structure and functional capabilities;
[0019] FIGS. 6a-c include diagrammatic, elevation view of the
active light modulating components of the segmented radial spatial
light modulator device to illustrate a use of an outer segment of a
vertically oriented sector of the light modulation components of
the segmented radial spatial light modulator device of this
invention along with diagrammatic views of an image being
characterized and a resulting detectable optic pattern that is
characteristic of some of the vertically oriented shape content of
the image;
[0020] FIGS. 7a-c include diagrammatic, elevation views similar to
FIGS. 6a-c, but illustrating a use of a near inner segment of the
vertical sector;
[0021] FIGS. 8a-b include diagrammatic, elevation views similar to
FIGS. 6a-c, but illustrating a use of a near outer segment of an
active optic sector that is oriented 45 degrees from vertical;
[0022] FIGS. 9a-c include diagrammatic, elevation views similar to
FIGS. 6a-c, but illustrating a use of the outer segment of the
horizontal oriented active optic sector;
[0023] FIGS. 10a-c include diagrammatic, elevation views similar to
FIGS. 6a-c, but illustrating a use of the outer segment of the
active optic sector that is oriented 191.25 degrees from
vertical;
[0024] FIG. 11 is a diagrammatic elevation view similar to FIG. 6a,
but illustrating a modified embodiment in which the active optic
segments are rectangular instead of wedge-shaped;
[0025] FIG. 12 is a diagrammatic elevation view of another
embodiment in which groups of individually addressable light
sensors in a pixel array of sensors can be activated together in
locations that simulate sectors or segments of sectors to achieve
angular and/or spatial analysis of a light beam for
characterization of an image by shape content according to this
invention;
[0026] FIG. 13 is a cross-section view similar to FIG. 4, but
illustrating a modification in which a modulated light beam passes
through, instead of being reflected by, a segmented radial spatial
light modulator in accordance with this invention;
[0027] FIGS. 14a-c illustrates an optional ghosting technique for
enhancing optical power transmission to improve shape information
detection capability and to provide graded shape content
characterization to enable identification of near matches of shape
content in various images; and
[0028] FIGS. 15a-c illustrate the ghosting technique of FIGS. 14a-c
applied to a slightly more complex image.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] A segmented radial spatial light modulator (SLM) device 50
according to the present invention is illustrated diagrammatically
in FIG. 1 with a beam of light 27(p) focused on the active optic
area 54 in the center portion of the segmented radial SLM device
50. As illustrated diagrammatically in FIG. 1, the segmented radial
SLM device 50 is preferably, but not necessarily, constructed as an
integrated circuit 52 mounted on a chip 56 equipped with a
plurality of electrical pins 58 configured to be plugged into a
correspondingly configured receptacle (not shown) on a printed
circuit board (not shown). In such a preferred embodiment, the pins
58 are connected electrically by a plurality of wires 59 soldered
to contact pads 55 of the integrated circuit 52 to enable
addressing and operating optic components in the active optic area
54, as will be discussed in more detail below.
[0030] An enlarged elevation view of the active optic area 54 of
the integrated circuit 52 is illustrated in FIG. 2, and an even
more enlarged view of the active optic segments 502, 504, 506, 508
of one sector 500 of the active optic area 54 is illustrated in
FIG. 3. Essentially, the segmented radial SLM device 50 is capable
of selectively isolating radially disposed portions of the incident
light energy at various angular orientations in relation to a
central axis 40 for detection, as will be explained in more detail
below. One way of accomplishing such isolation is by reflecting, as
well as rotating plane of polarization of, the selected radially
disposed portions of the light beam 27(p) that is incident on the
active optic area 54, while other portions of the light beam 27(p)
are reflected, but without rotation of the plane of polarization,
or vice versa. In the preferred embodiment, each of the active
optic segments, such as segments 520, 504, 506, 508 of sector 500
in FIG. 3, are addressable individually through electrically
conductive traces 503, 505, 507, 509, respectively, although the
invention also can be implemented, albeit with less spatial
frequency resolution, by a sector 500 comprising only one active
optic modulator or by activating one or more of the individual
segments simultaneously.
[0031] The selection and isolation of a portion of the incident
light beam 27(p) is illustrated in FIG. 4, which is a partial
cross-section of active optic segments 506, 508. An incident light
beam 27(p), which is designated, for examples as being p-polarized,
i.e., polarized in the p-plane, will be reflected by, and will
emerge from, segment 508 as s-polarized light 27(s), i.e., light
polarized in the s-plane, or vice versa, when the segment 508 is
activated by a voltage V+ on trace 509, while the unactivated
segment 506 reflects, but does not rotate plane of polarization of,
the incident light 27(p). In FIG. 4, the light reflected by the
activated segment 508 is designated as 61(s) to indicate its
s-plane polarization, while light reflected by the non-activated
segment 506 is designated as 61(p) to indicate its p-plane
polarization. The structure and function of the segments 506, 508,
which are typical of all the segments of all the sectors 500, 510,
520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640,
650 of the active optic area 54, will be explained in more detail
below. Suffice it to say at this point that a s-polarization plane
is orthogonal to i.e., rotated 90.degree. in relation to, a
p-polarization plane and that such rotation of plane of
polarization of a portion of a light beam 61 (p) (see FIG. 1)
enables filtration or separation of that portion from the remainder
of the light beam 61(p), as will be explained in more detail
below.
[0032] The system 10 for characterizing, encoding, and storing
images by shape content of such images, as illustrated
diagrammatically in FIG. 5, is an example application of the
segmented radial SLM device 50 described above and is a part of
this invention. In this system 10, any number n of images 12, 14, .
. . , n, can be characterized and encoded by the shape content in
such images, and such encoded shape information about each image
can be stored, for example, in database 102 for subsequent
searching, retrieval, and comparison to shape content of other
images that is characterized and encoded in the same manner.
[0033] The images 12, 14, . . . , n can be in virtually any form,
for example, visual images on photographs, films, drawings,
graphics, arbitrary patterns, ordered patterns, or the like. They
can also be stored and/or generated in or from digital formats or
analog formats. Such images can have content that is meaningful in
some manner when viewed by humans, or they can be meaningless or
not capable of being interrupted by humans but characteristic of
some other content, e.g., music, sounds, text, software, and the
like. Essentially, any optic pattern of light energy intensities
that can be manifested or displayed with discernable shape content
can be characterized and encoded with this system 10.
[0034] A sample image 12, which can be obtained from any source
(e.g., Internet, electronic data base, web site, library, scanner,
photograph, film strip, radar image, electronic still or moving
video camera, and other sources) is entered into the optical image
shape characterizer 10, as will be described in more detail below.
Any number n of other sample images 14, . . . , n, are shown in
FIG. 5 queued for entry in sequence into the optical image
characterizer 10. Entry of any number n of such sequential images
12, 14, . . . , n can be done manually or, preferably, in an
automated manner, such as a mechanical slide handler, a computer
image generator, a film strip projector, an electronic still or
video camera, or the like. The computer 20 in FIG. 5 is a preferred
embodiment, but is also intended to be symbolic of any apparatus or
system that is capable of queuing and moving images 12, 14, . . . ,
n into the image characterizer 10. The example image 12 of an
automobile displayed on the video monitor 22 represents and is
symbolic of any image that is placed in a process mode for
characterizing and encoding its shape content according to this
invention, although it should be understood that such display of
the image being processed is not an essential feature of this
invention. The description that follows will, for the most part,
refer only to the first image 12 for convenience and simplicity,
but with the understanding that it could apply as well to any image
12, 14, . . . , n etc.
[0035] In the embodiment of the system 10 illustrated in FIG. 5,
the image 12 is inserted into the optical image characterizer 10 in
an image plane 19 that is perpendicular to the beam of light 27
emanating from the E-SLM 26, i.e., perpendicular to the plane of
the view in FIG. 5. However, to facilitate explanation,
illustration, and understanding of the invention, the images 12,
14, . . . , n are also shown in phantom lines in the plane of the
view in FIG. 5, i.e., in the plane of the paper. This same
convention is also used to project image 12' produced by the E-SLM
26, the Fourier transform optic pattern 32, the active optic area
54, isolated and filtered optic pattern 60, and the detector grid
82 from their respective planes perpendicular to the light beams
into the plane of the paper for purposes of explanation,
illustration, and understanding. These components and their
functions in the invention will be explained in more detail
below.
[0036] As mentioned above, the image 12 can be entered into the
optical image characterizer 10 by the computer 20 and E-SLM 26, as
will be described in more detail below. However, the image 12 will
undergo a significant transformation upon passing through the thin,
positive lens 30, also called the Fourier transform (FT) lens. A
Fourier transform (FT) of the sample image 12' rearranges the light
energy of the optic pattern of image 12' into a Fourier transform
(FT) optic pattern 32, which is unique to the image 12', even
though it is not recognizable as the image 12' to the human eye and
brain, and which can be characterized by intensities, i.e.,
amplitudes, of light energy distributed spatially across the optic
pattern 32. The complex amplitude distribution of light energy 34
in the optic pattern 32 is the Fourier transform of the complex
light distribution in the image 12'. Image 12' is a recreation of
the image 12 in monochromatic, preferably coherent, light energy,
as will be described in more detail below, although white light
will also work. Concentrations of intense light energy in the
Fourier transform (FT) optic pattern 32 generally correspond to
spatial frequencies of the image 12', i.e., how closely together or
far apart features in the image 12' change or remain the same. In
other words, spatial frequencies are also manifested by how closely
together or far apart light energy intensities across the light
beam 27 change or remain the same. For example, a shirt with a
plaid fabric in an image (not shown), i.e., having many small
squares, would have a higher spatial frequency, i.e., changes per
unit of distance, than a plain, single-color shirt (not shown) in
the image. Likewise, portions of an image, such as the bumper and
grill parts 35 of the automobile in image 12', would have a higher
spatial frequency than the side panel 36 portion of the automobile
image 12', because the bumper and grill parts 35 comprise many
small pieces with various edges, curves, and other intricate
changes within a small spatial distance, whereas the side panel 36
is fairly smooth and uniform over a large spatial distance. Light
energy from the finer and sharper details of an image (more spatial
frequency), such as the more intricate bumper and grill parts 35 of
the image 12', tend to be dispersed farther radially outward from
the optical center or axis 40 in the Fourier transformed image than
light energy from more course or plain details of an image (less
spatial frequency), such as the side panel 36 of the image 12'. The
amplitude of light energy 34 dispersed radially outward in the
Fourier transform optic pattern 32 is related to the light energy
of the corresponding portions of the optic pattern of image 12'
from which such light energy emanates, except that such light
energy is concentrated into areas or bands 34 at the plane of the
Fourier transform (FT) optic pattern 32 after they are refracted by
the FT lens 30, i.e., into bands of intense light energy separated
by bands of little or no light energy, which result from
constructive and destructive interference of the diffracted light
energy. If the high spatial frequency portions of the image 12',
such as the bumper and grill portion 35, are bright, then the
intensity or amplitude of light energy from those high spatial
frequency portions of the image 12', which are dispersed by the FT
lens 30 to the more radially outward bands of light energy 34 in
the Fourier transform optic pattern 32, will be higher, i.e.,
brighter. On the other hand, if the high spatial frequency portions
of the optic pattern of image 12' are dim, then the intensity or
amplitude of light energy from those high spatial frequency
portions of the optic pattern of image 12', which are dispersed by
the FT lens 30 to the more radially outward bands of light energy
34 in the Fourier transform optic pattern 32, will be lower, i.e.,
not so bright. Likewise, if the low spatial frequency portions of
the optic pattern of image 12', such as the side panel portion 36,
are bright, then the intensity or amplitude of light energy from
those low spatial frequency portions of the optic pattern of image
12' which are dispersed by the FT lens to the less radially outward
bands of light energy 34 in the Fourier transform optic pattern 32
(i.e., closer to the optical axis 40), will be higher, i.e.,
brighter. However, if the low spatial frequency portions of the
optic pattern of image 12' are dim, then the intensity or amplitude
of light energy from those low spatial frequency portions of the
optic pattern of image 12', which are dispersed by the FT lens 30
to the less radially outward bands of light energy 34 in the
Fourier transform optic pattern 32, will be lower, i.e., not so
bright.
[0037] In summary, the Fourier transform optic pattern 32 of the
light emanating from the image 12': (i) is unique to the image 12';
(ii) comprises areas or bands of light energy 34 concentration,
which are dispersed radially from the center or optical axis 40,
that represent spatial frequencies, i.e., fineness of details, in
the image 12'; (iii) the intensity or amplitudes of light energy 34
at each spatial frequency area or band in the Fourier transform
optic pattern 32 corresponds to brightness or intensity of light
energy emanating from the respective fine or course features of the
image 12'; and (iv) such light energy 34 in the areas or bands of
the Fourier transform optic pattern 32 are detectable in intensity
and in spatial location by this invention.
[0038] Since this optical image characterizer 10 of this invention
is designed to characterize an image 12 by shapes that comprise the
image 12, additional spatial filtering of the Fourier transform
light energy pattern 32 is used to detect and capture light energy
emanating from the finer or sharper details or parts of such finer
or sharper details in the image 12', which are aligned linearly in
various specific angular orientations. Such spatial filtering can
be accomplished in any of a number of different ways, as will be
explained in more detail below, but an exemplary spatial filter
arrangement for this function is included in a combination of the
segmented radial spatial light modulator device 50 with the
polarizing beam splitter 70. Essentially, the segmented radial SLM
device 50 rotates the plane of polarization of selected portions of
the Fourier transform optic pattern 32 from p-plane polarization to
s-plane polarization, or vice versa, as explained above, and the
polarizing beam splitter 70 separates light energy of those
portions that is isolated and polarized in one plane from the light
energy of the rest of the Fourier transform optic pattern 32 that
remains polarized in the other plane so that such light energy of
the selected and isolated portions can be detected separately.
[0039] Only the portions of the light energy 34 in the Fourier
TRANSFORM pattern 32 that align linearly with selected active optic
segments, for example, segment 502, 504, 506, and/or 508 (FIG. 3),
have the plane of polarization rotated in the reflected light 61
(s) by the segmented radial SLM 50. Such selected portions 61(s) of
the beam 27(p) represent, i.e., emanated largely from, details or
features of the image 12', such as straight lines and short
segments of curved lines, that align linearly with the angular
orientation of the respective sectors 500, 510, 520, 530, 540, 550,
560, 570, 580, 590, 600, 610, 620, 630, 640, 650 in which selected
segments are located in the active optic area 54 of the segmented
radial SLM 50. For example, if one or more of the segments 502,
504, 506, 508 in sector 500 is selected and activated to rotate
plane of polarization of light energy reflected from such
segments(s), the reflected light energy 61(s) will have emanated
largely from details or features of the image 12' that align
linearly with the vertical orientation of the sector 500 in which
segments 502, 504, 506, 508 are positioned. Further, since the
light energy 34 from higher spatial frequency content of the image
12', e.g. , closely spaced bumper and grill parts 35, are dispersed
farther radially outward in the Fourier transform optic pattern 32
than light energy 34 from lower spatial frequency content, e.g. ,
side panel 36, the light energy in reflected light beam 61(s) will
also be characteristic of a confined range of such spatial
frequency content of image 12', depending on which segment of a
sector is selected. For example, activation of outer segment 508 of
sector 500 (FIG. 3), which is positioned farther radially outward
from the optic axis 40 of the incident beam 27(p) than segment 502,
will cause the light energy in reflected beam 61 (s) to be
characteristic of higher spatial frequency content of vertically
oriented features in image 12', e.g. , vertical edges of bumper and
grill parts 35. In contrast, activation of inner segment 502 of
sector 500, will cause the light energy in reflected beam 61(s) to
be more characteristic lower spatial frequency content of
vertically oriented features in the image 12', e.g. , the vertical
rear edge of the trunk lid 37. The result is a filtered pattern 60
of light energy bands 62 that represent or are characteristic of
the unique combination of features or lines in the content of image
12' that corresponds to light energy of the FT optic pattern 32 at
the radial distance of the selected segment and that align linearly
with the sector in which the selected segment is positioned.
Therefore, in addition to being able to provide rotational spatial
filtering of the FT optic pattern 32 at different angular
orientations about the optic axis, the segments of each sector,
such as segments 502, 504, 506, 508 of sector 500, provided the
additional capability of scalar spatial filtering FT optic pattern
32 at different radial distances from the optic axis.
[0040] Of course, segments in different sectors of different
angular orientations about the optic axis 40 will align linearly
with features or lines in the image 12' that have different angular
orientations, as will be described in more detail below. Thus, the
light energy bands 62 in the filtered pattern 60 will change, as
active optic segments in different sectors are selected and
activated, to represent different features, details, edges, or
lines in the optical pattern of image 12' at various angular
orientations, intricateness or fineness, and brightness, as will be
explained in more detail below. In general, however, the light
energy bands 62, if inverse Fourier transformed from the FT optic
pattern 32 after the above-described spatial filtering 54, will be
located in the same spatially-related sites as the features in the
original image 12' from which such light energy emanated. For
example, light energy in a band 62 in pattern 60 that originally
emanated from bumper and grill parts 35 in image 12', after spatial
filtering with the vertical sector of the bumper and grill parts 35
in image 12'.
[0041] The spatially filtered light energy in bands 62 of the
filtered pattern 60 can be detected by a photodetector 80 at any of
the various angular orientations of the activated sectors and fed
electronically to a computer 20 or other microprocessor or computer
for processing and encoding. While only one photodetector 80 with
an example 16.times.16 array 82 of individual photosensitive energy
transducers 84 is illustrated in FIG. 5 and is sufficient for many
purposes of this invention, other detector arrangements, for
example, the two offset detector arrays described in co-pending
patent application, Ser. No. 09/536,426, or one or more larger
detector arrays, could also be used.
[0042] The computer 20, with input of information about the
filtered optical patterns 60, i.e., light energy intensity (I)
distribution, from the detector array 82, along with information
about the image 12 (e.g. , identification number, source locator,
and the like), information about the angular orientation (R) of the
sector in which a segment is activated, and information about the
radial distance or scale (S) of the activated segment relating to
spatial frequency, can be programmed to encode the characteristics
of the image 12 relating to the shape content of the image 12. One
useful format for encoding such information is by pixel of the
filtered image 60, including information regarding x, y coordinate
location of each pixel, Rotation (i.e., angular orientation of the
sector in which a segment is activated, thus of the linear features
of the image 12 that align with such angular orientation), and
Intensity (i.e., amplitude of light energy from the filtered
pattern 60 that is detected at each pixel at the angular
orientation R. A searchable flag, such as a distortion factor X,
can also be provided, as explained in more detail co-pending patent
application, Ser. No. 09/536,426 or by the ghost image
pre-processing feature of this invention, which will be explained
in more detail below. Such combination of angular orientation or
rotation R, light energy intensity I for each pixel, and distortion
factor X can be called a "RIXel" for short. Scale (i.e., spatial
frequencies of image 12 content at such angular orientations) can
also be included in such encoding, if desired. When including a
scale factor S, the combination can be called a "RIXSel". Each
RIXel or RIXSel can then be associated with some identifier for the
image 12 from which it was derived (e.g. , a number, name, or the
like), the source location of the image 12 (e.g. , Internet URL,
data base file, book title, owner of the image 12, and the like),
and any other desired information about the image, such as format,
resolution, color, texture, content description, search category,
or the like. Some of such other information, such as color,
texture, content description, and/or search category, can be
information input from another data base, from human input, or even
from another optical characterizer that automatically characterizes
the same image 12 as to color, texture, or the like--whatever would
be useful for searching, finding, or retrieving image 12 or for
comparing image 12 to other images.
[0043] Some, all, or additional combinations of such information
about each image 12, 14 . . . , n characterized for shape and
encoded, as described above, can be sent by the computer 20 to one
or more data base(s) 102. Several example data base architectures
104, 106, 108 for storing RIXel or RIXSel information about each
image 12, 14, . . . , n are shown in FIG. 5, but many other
architectures and combinations of information could also be
used.
[0044] In the optical image characterizer 10 illustrated in FIG. 5,
the image 12 has to be recreated with monochromatic, preferably
coherent, light energy, e.g. , at image 12', with a spatial light
modulator (SLM) 26 illuminated with a beam of monochromatic light
24 from a light source 23, such as a laser diode or gas diode. This
feature of the invention could also be implemented with white
light, although the resultant Fourier transform optic patterns and
spatially filtered optic patterns would be more blurred than with
monochromatic light. Therefore, while this description of the
invention will proceed based on monochromatic, preferably coherent,
light, it should be understood that white light is a suitable,
albeit not a preferred, substitute. The spatial light modulator
(SLM) 26 can be optically addressable (0-SLM), such as the one
illustrated in co-pending patent application 09/536,426, or it can
be electrically addressable (E-SLM) and driven, for example, by a
computer 20 in FIG. 5 or by a video camera (not shown). As is known
by persons skilled in the art, a spatial light modulator (SLM) can
"write" an image into a polarized beam of light 25 by rotating or
partially rotating the polarization plane of the light on a spatial
basis across the beam 25 so that, upon reflection as beam 27, it is
either transmitted through, or reflected by, the polarization beam
splitter 116, depending on what is needed to create the image 12'
in monochromatic light. In an optically addressed SLM (not shown),
the image plane is addressed on a spatial basis by incident light
energy on a semiconductor material adjacent the polarization
rotating material (usually a liquid crystal material), whereas, in
an electrically addressable SLM 26, the liquid crystal,
polarization rotating material is addressed electrically on a pixel
by pixel basis. The pixel portions of the polarized light that have
the plane of polarization rotated 45 degrees as they pass once
through the liquid crystal material, whereupon such light is
reflected and passed back through the liquid crystal again, where
it is rotated another 45 degrees. Thus, the pixels of light in
polarized beam 25 that have their plane of polarization rotated in
the SLM 26 are reflected and emerge from the SLM along the optical
path 27, which has an optic axis 40 that coincides with the optic
axis of the incident beam 25 but in an optic pattern imposed by the
E-SLM 26 that forms an image 12' and with its plane of polarization
rotated 90 degrees from the plane of polarization of the incident
beam 25. The remaining pixels of light, which do not undergo
rotation of the plane of polarization, are also reflected, but they
can be separated from those that have undergone rotation of plane
of polarization, as will be explained below. Various light
intensities or brightnesses of the image 12 can be recreated in
gray scales in image 12' by partial rotations of plane of
polarization.
[0045] In the FIG. 5 embodiment, the coherent light beam 24 from
laser source 23 is passed first through a polarizer 28 to create a
polarized beam of coherent light 25 with all the light polarized in
one plane, such as, for example, but not for limitation, in the
s-plane, as indicated by 25(s). The s-polarized beam 25(s) is then
passed through a spatial filter 110 comprised essentially of a pin
hole 112 and a lens 114 to focus the beam 25(s) on the pin hole
112. This spatial filter 110 is provided primarily to condition the
beam 25(s) to get a good Gaussian wavefront and, if necessary, to
limit the power of the beam 25(s). Lens 114a then columnates the
light.
[0046] The beam 25(s) is then passed through a polarizing beam
splitter 116, which reflects light polarized in one direction at
plane 118 and transmits light polarized in the orthogonal
direction. In this example, the polarizing beam splitter 116
reflects s-polarized light and transmits p-polarized light, and it
is oriented to reflect the s-polarized beam 25(s) toward the
electrically addressed spatial light modulator (E-SLM) 16. (the
monochromatic, preferably coherent, light beam 25(s) incident on
the E-SLM 36 provides the light energy that is utilized to carry
the shape content of the image 12' for further analysis,
characterization, and encoding according to this invention.
[0047] As mentioned above, there are many ways of "writing" images
12, 14, . . . , n into a light beam, one of which is with an E-SLM
16. In this example, computer 20 has the content of image 12
digitized, so the computer 20 can transmit digital signals via link
21 to the E-SLM 26 in a manner that addresses and activates certain
pixels in the E-SLM 26 to "write" the image 12' into reflected
light beam 27(p), as is understood by persons skilled in the art.
Essentially, the addressed pixels rotate the plane of polarization
by 90 degrees from the s-plane of incident beam 25(s) to the
p-plane of reflected beam 27(p), or by some lesser amount for
gray-scales, in a manner such that the reflected light energy with
partially or fully 90-degree polarization plane rotation is in an
optical pattern of the image 12'. Of course, persons skilled in the
art will also understand that the image 12' could also be created
with an E-SLM that operates in an opposite manner, i.e., the plane
of polarization is rotated in reflected light, except where pixels
are activated, in which case the computer 20 would be programmed to
activate pixels according to a negative of the image 12 in order to
write the image 12' into reflected beam 27. Either way, the
emerging beam 27(p) of coherent light, carrying image 12', is
p-polarized instead of s-polarized or vice versa. Consequently, in
the above example, the monochromatic light beam 27(p), with its
light energy distributed in an optic pattern that forms the image
12', is transmitted by the polarizing beam splitter 116 to the FT
lens 30, instead of being reflected by it.
[0048] The positive Fourier transform (FT) lens 30, as explained
above is positioned in the light beam 27(p) and redistributes the
monochromatic light energy from the image 12' into its Fourier
transform optic pattern 32, which occurs at the focal plane of the
FT lens 30. Therefore, the segmented radial SLM 50 of this
invention has to be positioned in the focal plane of the FT lens
30, as indicated by the focal distance F in FIG. 5, and the FT lens
30 is also positioned the same focal distance F from the E-SLM 26,
so that the E-SLM 26 is also in a focal plane of the lens 30. As
also explained above, the complex amplitude distribution of light
energy 34 in the Fourier transform optic pattern 32 at the focal
plane of the FT lens 30 is the Fourier transform of the complex
amplitude distribution in the image 12'. The Fourier transform
optic pattern 32 has all of the light energy from the image 12'
distributed into the symmetrical pattern 32 based on the spatial
frequencies of the image 12', with intensities of the light energy
in the various spatial frequency distributions 34 based on the
light energy in the corresponding portions of the image 12' where
those respective spatial frequencies occur.
[0049] The Fourier transform optic pattern 32, as mentioned above,
is symmetrical from top to bottom and from left to right, so that
each semicircle of the Fourier transform optic pattern 32 contains
exactly the same distribution and intensity of light energy as its
opposite semicircle. Light energy from lower spatial frequencies in
the image 12' are distributed toward the center or optical axis 40
of the Fourier transform optic pattern 32, while the light energy
from higher spatial frequencies in the image 12' are distributed
farther away from the optical axis 40 and toward the outer edge of
the pattern 32, i.e., farther radially outward from the optic axis
40. Light energy from features in the image 12' that are
distributed vertically in the image 12' to create those various
spatial frequencies is likewise distributed vertically in the
Fourier transform optic pattern 32. At the same time, light energy
from features in the image 12' that are distributed horizontally in
the image 12' to create those various spatial frequencies is
distributed horizontally in the Fourier transform optic pattern 32.
Therefore, in general, light energy from features in the image 12'
that are distributed in any angular orientation with respect to the
optical axis 40 to create the various spatial frequencies in the
image 12' is also distributed at those same angular orientations in
the Fourier transform optic pattern 32. Consequently, by detecting
only light energy distributed at particular angular orientations
with respect to the optical axis 40 in the Fourier transform optic
pattern 32, such detections are characteristic of features or
details in the image 12' that are aligned linearly in such
particular angular orientations. The radial distributions of such
detected light energy at each such angular orientation indicate the
intricateness or sharpness of such linear features or details in
the image 12', i.e., spatial frequency, while the intensities of
such detected light energy indicate the brightness of such features
or details in the image 12'.
[0050] Therefore, a composite of light energy detections at all
angular orientations in the Fourier transform optic pattern 32
creates a composite record of the shapes, i.e., angular
orientations, intricateness or sharpness, and brightness, of linear
features that comprise the image 12'. However, for most practical
needs, such as for encoding shape characteristics of images 12, 14,
. . . , n for data base storing, searching, retrieval, comparison
and matching to other images, and the like, it is not necessary to
record such light energy detections for all angular orientations in
the Fourier transform pattern 12'. It is usually sufficient to
detect and record such light energy distributions and intensities
for just some of the angular orientations in the Fourier transform
optic pattern 32 to get enough shape characterization to be
practically unique to each image 12, 14, . . . , n for data base
storage, searching, and retrieval of such specific images 12, 14, .
. . , n. For purposes of explanation, but not for limitation, use
of 11.25-degree angular increments is convenient and practical,
because there are sixteen (16) 11.25-degree increments in 180
degrees of rotation, which is sufficient characterization for most
purposes and has data processing and data storage efficiencies, as
explained in co-pending U.S. patent application, Ser. No.
09/536,426. However, other discrete angular increments could also
be used, including constant increments or varying increments. Of
course, varying increments would require more computer capacity and
more complex software to handle the data processing, storing, and
searching functions.
[0051] In the preferred embodiment of this invention, the segmented
radial SLM 50, shown in FIG. 1, with its active optic sectors 500,
510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630,
640, 650 shown in FIG. 2, is used to select only light energy from
specific angular orientations in the Fourier transform optic
pattern 32 for detection at any instant in time or increment of
time on the detector array 82. As explained above with reference to
the sector 500 in FIG. 3, which, except for angular orientation, is
typical of all the other sectors 510, 520, 530, 540, 550, 560, 570,
580, 590, 600, 610, 620, 630, 640, 650 in FIG. 2, any active optic
segment, e.g. , segments 502, 504, 506, 508, in vertical sector
500, can be addressed via respective electric traces, e.g. , traces
503, 505, 507, 509 for sector 500, so that the detector array 82
can detect light energy distribution and intensity (I) in the
Fourier transform optic pattern 32 at any angular orientation (R)
of a sector 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600,
610, 620, 630, 640, 650 and at selected radial distances from the
optic axis 40. For example, sector 500 is oriented substantially
vertical in relation to the optic axis 40. If all of the active
optic segments 502, 504, 506, 508 of sector 500 are selected and
activated simultaneously, virtually all of the light energy that is
distributed vertically in the Fourier transform optic pattern 32
will be incident on, and detected by, the photodetector array 82
(FIG. 5). However, if only one of the active optic segments, for
example, outer segment 508, is selected and activated, then only
the light energy in the Fourier transform optic pattern 32 that is
distributed vertically and the farthest radially outward from the
optic axis 40 will be detected by the photodetector array 82. Thus,
any one, all, or combination of the active optic segments, e.g. ,
502, 504, 506, 508, can be activated sequentially or simultaneously
to detect and record various distributions of light energy in the
Fourier transform optic pattern 32. Also, any one or more sectors
500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620,
630, 640, 650 can be selected and activated sequentially,
simultaneously, or in various combinations, depending on the detail
or particular light energy distributions in the FT optic pattern 32
it is desired to detect.
[0052] The preferred, but not essential, shape of the active optic
sectors, e.g. , sector 500, in the segmented radial SLM 50 is a
narrow, elongated wedge. The width of the wedge will depend on the
light energy available or needed and the optic resolution desired.
A wider sector will direct more light energy 34 to the detector 80,
but precision of line or feature resolution of the image 12' will
degrade slightly. A narrower sector will get better line
resolution, but with a corresponding increase in the complexity of
the resulting pattern shape generalization and complexity and a
decrease in light energy directed to the detector 80. There may
also be a practical limitation as to how narrow and close the
wedges can be made with the connecting electric traces in a limited
active optic area 54 in an economic and efficient manner.
Therefore, a desirable balance between these resolution,
detectability, and size considerations may be struck in choosing
sector size. Also, for specialized applications, sectors of
different shapes (not shown), such as ovals, or other shapes could
be used to capture shapes other than lines from the image 12.
[0053] The number of active optic segments in a sector, e.g. , the
four segments 502, 504, 506, 508 sector 500, also has similar
constraints. Smaller segments direct less light energy to the
detector 80, but may provide more resolution of shape
characteristics of the image 12', whereas larger segments direct
more light to the detector 80, thus are more easily detectable, but
resolution decreases. For lower resolution applications or
requirements, the sectors may not even need to be divided into
segments, and this invention includes radial spatial light
modulators in which each sector 500, 510, 520, 530, 540, 550, 560,
570, 580, 590, 600, 610, 620, 630, 640, 650 is not segmented, thus
comprises a single active optic element for each sector. However,
the same lower resolution effect can be achieved in the illustrated
embodiment 50 in FIGS. 1-3 by activating all the segments 502, 504,
506, 508 in a sector simultaneously, as described above.
[0054] In the preferred embodiment 50, each sector, e.g. , sector
500, comprises four individually addressable, active optic
segments, e.g. , segments 502, 504, 506, 508, as shown in FIG. 3,
although any number of segments other than four can also be used
according to this invention. The length of each successive radial
outward segment is twice as long as the next adjacent radially
inward segment. Thus, in sector 500, the near inner segment 504 is
about twice as long as the inner segment 502. Likewise, the near
outer segment 506 is about twice as long as the near inner segment
504, and the outer segment 508 is about twice as long as the near
outer segment 506. Expressed another way, if the radial length of
inner segment 502 is L, the radial length of near inner segment 504
is 2L, the radial length of the near outer segment 506 is 4L, and
the radial length of the outer segment 508 is 8L. The distance d
between the optic axis 40 and the inner edge 501 of inner segment
502 is about the same as the length L of inner segment 502, so the
diameter of the center area 57 is about 2L. These proportional
lengths of the active optic segments enable the inner segments
(e.g., 502) to capture shape features of the image 12' that have
sizes] in a range of about 25-50 percent of the size of the image
12' produced by the spatial light modulator 26 in FIG. 5, the near
inner segments (e.g., 504) to capture shape features of the image
12' that have sizes in a range of about 12{fraction (1/2)}-25
percent of the size of image 12', the near outer segments (e.g. ,
506) to capture shape features of the image 12' that have sizes in
a range of about 61/4-121/2 percent of the size of image 12, and
the outer segments (e.g. , 508) to capture shape features of the
image 12' that have sizes in a range of about 31/8-61/4 percent of
the size of the image 12'. Therefore, any features of the image 12'
that have sizes over 50 percent of the size of image 12', which
light energy is incident on the center area portion 41, can either
be captured and detected as an indicator of general brightness of
the image 12' for intensity control or calibration purposes or just
ignored and not captured or detected at all, because there is
little, if any, useable shape information or content in the light
energy that comprises that 50 percent of the size of the image 12'.
Likewise, the approximately 31/8 percent of the size content of the
image 12' that is radially outward beyond the outer segments is not
detected and can be ignored in this preferred configuration. The
light in the center 41 can be made optically active to capture
light energy incident thereon, if it is desired to capture and
detect such light energy for general brightness indication,
intensity control, or calibration purposes, as will be understood
and within the capabilities of persons skilled in the art, once
they understand this invention. Of course, other configurations of
the segmented radial SLM 50 could also be made and used within the
scope of this invention.
[0055] While the radial configuration of the active optic sectors
with or without the multiple, active optic segments in each sector
in the spatial light modulator 50 is a significant feature of this
invention, persons skilled in the art of designing and fabricating
spatial light modulators can readily understand how such a spatial
light modulator 50 can be constructed and function, once they
become familiar with the features and principles of this invention,
and there are many known materials, fabrication techniques, and the
like, known to persons skilled in the art that could be used to
design, make, and use state-of-the-art spatial light modulators
that are applicable to the specialized spatial light modulator
embodiments of this invention. Therefore, a detailed recitation of
such available materials is not necessary to enable a person
skilled in the art to make and use this invention. Never-the-less,
reference is now made to FIG. 4 in combination with FIGS. 1-3 and 5
to illustrate how selection and activation of any particular active
optic segment, for example, near outer segment 506 and outer
segment 508, function to selectively enable detection of light
energy from the Fourier transform optic pattern 32 that is incident
on such segments.
[0056] As illustrated in FIG. 4, the optic active segments 506,
508, which are typical of other active optic segments, are part of
an integrated circuit 52, which is mounted on a chip base or
platform 56. The integrated circuit 52 has a variable birefringent
material 180, such as a liquid crystal material, sandwiched between
two transparent substrates 182, 184, such as high quality glass.
The variable birefringent material 180 is responsive to a voltage
to change its birefringence in the area of the voltage, which
results in rotation of the plane of polarization of the light that
passes through the material 180. The division between near outer
segment 506 and outer segment 508 is made by a separation of
respective metal layers 186, 188. An intervening dielectric or
electrical insulation material 185 can be used to maintain
electrical separation of these metal layers 186, 188. As shown by a
combination of FIGS. 3 and 4, electrically conductive trace 507 is
connected to the metal layer 186 of near outer segment 506, and
trace 509 is connected to the metal layer 188 of outer segment 508.
In fact, the electric traces 507, 509 and metal layers 186, 188 can
be deposited the same metal and can be on the back substrate 184
concurrently with their respective metal layers 186, 188 during
fabrication of the integrated circuit 52, as would be understood
and within the capabilities of persons skilled in the art of
designing and fabricating spatial light modulators, once they are
informed of the principles of this invention. Therefore, the metal
layers 186, 188 can be addressed individually through their
respective connected traces 507, 509 by connecting positive (+) or
negative (-) voltages V.sub.1 and V.sub.2, respectively, to traces
507, 509.
[0057] A transparent conductive layer 190 deposited on the front
substrate 182 is connected by another lead 513 to another voltage
V.sub.3. Therefore, a voltage can be applied across the portion of
the liquid crystal material 180 that is sandwiched between the
metal layer 186 and the transparent conductive layer 190 by, for
example, making V.sub.1 positive and V.sub.3 negative and vice
versa. Likewise, when a voltage can be applied across the portion
of the liquid crystal material 180 that is sandwiched between the
metal layer 188 and the transparent conductive layer 190 by, for
example, making V.sub.2 positive and V.sub.3 negative and vice
versa.
[0058] As mentioned above, the function of the respective segments
506, 508 is to rotate the plane of polarization of selective
portions of the incident light beam 27(p) so that those portions of
the light beam 27(p), which carry corresponding portions of the
Fourier transform optic pattern 32, can be separated and isolated
from the remainder of the light beam 27(p) for detection by the
photodetector array 82 (FIG. 5). As understood by persons skilled
in the art, there are a number of spatial light modulator
variations, structures, and materials that can yield the desired
functional results, some of which have advantages and/or
disadvantages over others, such as switching speeds, light
transmission efficiencies, costs, and the like, and many of which
would be readily available and satisfactory for use in this
invention. Therefore, for purposes of explanation, but not for
limitation, the segmented radially spatial light modulator
illustrated in FIG. 4 can have respective alignment layers 192, 194
deposited on the transparent conductive layer 190 on substrate 182
and on the metal layers 186, 188 on substrate 184. These alignment
layers 192, 194 are brushed or polished in a direction desired for
boundary layer crystal alignment, depending on the type of liquid
crystal material 180 used, as is well-understood in the art. See,
e.g., J. Goodman, "Introduction to Fourier Optics, 2.sup.nd ed. ,
chapter 7 (The McGraw Hill Companies, Inc.) 1996. An antireflective
layer 196 can be deposited on the outside surface of the glass
substrate 182 to maintain optical transmissive efficiency.
[0059] One example system, but certainly not the only one, can use
a liquid crystal material 180 that transmits light 27(p) without
affecting polarization when there is a sufficient voltage across
the liquid crystal material 180 and to act as a 1/4-wave retarder
when there is no voltage across the liquid crystal material. An
untwisted crystal material 180 that is birefringent in its
untwisted state can function in this manner. Thus, for example,
when no voltage is applied across the liquid crystal material 180
in segment 508, there is no molecular rotation of the liquid
crystal material 180 in outer segment 508, and the liquid crystal
material in outer segment 108, with the proper thickness according
to the liquid crystal manufacturer's specifications, will function
as a 1/4-wave plate to convert p-polarized light 27(p) incident on
outer segment 508 to circular polarization as the light passes
through the untwisted liquid crystal material 180. Upon reaching
the metal layer 188, which is reflective, the light is reflected
and passes back through the liquid crystal material to undergo
another 1/4-wave retardation to convert the circular polarization
to linear polarization, but in the s-plane, which is orthogonal to
the p-plane. The reflected light 61(s), therefore, has its plane of
polarization effectively rotated by 90 degrees in relation to the
incident light 27(p).
[0060] Meanwhile, if there is a sufficient voltage on, for example,
the near outer segment 506, to rotate the long axes of the liquid
crystal molecules into alignment with the direction of propagation
of the incident light waves 27(p), thereby eliminating the
birefringence of the liquid crystal material 180, then there is no
change of the linear polarization of the light on either its first
pass through the liquid crystal material 180 or on its second pass
through the liquid crystal material after being reflected by metal
layer 186. Consequently, under this condition with a voltage
applied across the liquid material 180 in ear outer segment 506,
the reflected light 61(p) is still polarized in the p-plane, i.e.,
the same plane as the incident light 27(p).
[0061] Many liquid crystal materials require an average DC voltage
bias of zero, which can be provided by driving the voltage V.sub.3
with a square wave function of alternating positive and negative
voltages for equal times. Therefore, for no voltage across the
liquid crystal material 180, the other voltages V.sub.1, V.sub.2,
etc. , can be driven in phase with equal voltages as V.sub.3.
However, to apply a voltage across the liquid crystal material 180
adjacent a particular metal layer 186, 188, etc. , to activate that
particular segment 506, 508, etc. , as described above, the
respective voltage V.sub.1 or V.sub.2, etc. , can be driven out of
phase with V.sub.3. If the frequency of the square wave function is
coordinated with the switching speed of the liquid crystal material
180, one-half cycle out of phase for a voltage V.sub.1, V.sub.2,
etc. , will be enough to activate the liquid crystal material 180
to rotate the plane of polarization of the light as described
above.
[0062] As mentioned above, other alternate arrangements and known
liquid crystal materials can reverse the results from an applied
voltage. For example, a twisted liquid crystal material 180 may be
used to rotate plane of polarization under a voltage and to not
affect plane of polarization when there is no voltage.
[0063] Referring again primarily to FIG. 5 with continuing
secondary reference to FIG. 4, the light energy in the beam 27'(p),
which passes through the polarizing beam splitter 116 and 70
without reflection by planes 116 and 72, is focused as the Fourier
transform optic pattern 32 on the segmented radial SLM 50. Selected
active optic segments, for example, segments 502, 504, 506, 508, in
the segmented radial SLM, can rotate the plane of polarization of
portions of the incident light beam 27(p), as described above, in
order to separate and isolate light energy from selected portions
of the FT optic pattern 32 for detection by photodetector 80. The
computer 20 can be programmed to provide signals via link 198 to
the segmented radial SLM 50 to select and coordinate activation of
particular segments, for example, segments 502, 504, 506, 508, with
displays of particular images 12, 14, . . , n. The computer 20 can
also be programmed to coordinate laser source 23 via a link 29 to
produce the required light energy 24, when the selected segment of
the segmented radial SLM 50 is activated.
[0064] The reflected light 61(s) from the segmented radial SLM 50,
e.g. , light polarized in the s-plane reflected from an activated
segment, as explained above, does not pass back through the
polarizing beam splitter 70 along with p-polarized reflected light.
Instead, the s-polarized reflected light 61(s) is reflected by the
plane 72 in the polarizing beam splitter 70 to the detector 80. The
lens 78 magnifies and focuses the isolated beam 61(s) in a desired
size on the detector array 82 of photodetector 80.
[0065] The photodetector array 82, as mentioned above, can be a
16.times.16 array of individual light sensors 84, such as charge
coupled devices (CCDs), as shown in FIG. 5, or any of a variety of
other sizes and configurations. The x, y coordinates of individual
sensors 84 in the array 82 that detect light 61 (s) can be
communicated, along with light intensity (I) information, to the
computer 20 or other controller or recording device via a link 86,
where it can be associated with information bout the image 12, 14,
. . . , n and the angular orientation and/or radial position of the
activated segment(s) in the segmented radial SLM 50 that provided
the beam 61(s) to the detector 80.
[0066] The spatial filtering process described above and its
characterization of the image 12 by shape content is illustrated in
more detail in FIGS. 6a-c, 7a-c, 8a-c, 9a-c, and 10a-c. With
reference first to FIG. 6a, the active optic area 54 from FIGS. 1
and 2 is shown in FIG. 6a with the example sectors 500, 510, 520,
530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650,
but, to avoid unnecessary clutter, without the electric traces that
were described above and shown in FIGS. 1-3. As mentioned above,
the sectors can be any desired width or any desired angular
orientation, but a convenient, efficient, and effective
configuration is to provide sectors of 11.25.degree.. For example,
a circle of 360.degree. divides into 32 sectors of 11.25.degree.
each, and a semicircle of 180.degree. divides into sixteen sectors
of 11.25.degree. each. Further, as mentioned above, the light
energy distribution in any semicircle of a Fourier transform optic
pattern 32 is symmetric with its opposite semicircle. Therefore,
detection of the light energy pattern in one semicircle of the FT
optic pattern 32, for example, in the semicircle extending from
0.degree. to 180.degree., provides effective information for the
entire image 12', and detection of the light energy pattern in the
opposite semicircle extending from 180.degree. to 360.degree.
provides the same information. Consequently, to alleviate clutter
and better accommodate the electric traces (shown in FIGS. 1-3,
some of sectors can be positioned in one semi-circle of the optic
area 54 with intervening spaces to accommodate the electric traces
(shown in FIGS. 1-3), while others of the sectors can be positioned
in the opposite semicircle of the optic area 54 diametrically
opposite to the intervening spaces. For example, when the circle is
divided into 32 sectors of 11.25.degree. each, only 16 of those
sectors, such as sectors 500, 510, 520, 530, 540, 550, 560, 570,
580, 590, 600, 610, 620, 630, 640, 650 have to be optically active
to detect all of the light energy incident on the area 54. All 16
of such optically active sectors could be positioned in one
semicircle of the area 54, or, as explained above, it is more
convenient and less cluttered to position some of the optically
active sectors in one semicircle with intervening spaces and others
in the opposite semicircle diametrically opposite to the
intervening spaces. In the example of FIG. 6a, any eight of the
sectors, e.g. , sectors 640, 650, 500, 510, 520, 530, 540, 550,
separated by non-active areas 641, 651, 501, 511, 521, 531, 541,
are positioned in one semicircle of the area 54, while the
remaining eight of the sectors 560, 570, 580, 590, 600, 610, 620,
630, also separated by non-active areas 561, 571, 581, 591, 601,
611, 621, can be positioned in the opposite semicircle, as shown in
FIG. 6a. When each of the 16 active optic sectors 500, 510, 520,
530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650 in
this arrangement is positioned diametrically opposite a non-active
area, the symmetry of the FT optic pattern 32 (FIG. 5) effectively
allows all of the light energy distribution in FT optic pattern 32
to be directed with these sectors.
[0067] This principle also facilitates design and fabrication of an
effective segmented radial SLM 50, because, for every active optic
sector, there can be an adjacent inactive sector or area available
for placement of electrically conductive traces to the segments, as
shown by reference back to FIGS. 2 and 3. For example, the inactive
area 651 between active optic segments 500 and 650 accommodates
placement of traces 503, 505, and 507 (shown in FIG. 3) to
respective segments 502, 504, 506 of active optic sector 500. To
provide active optic sectors to detect light energy incident on the
non-active areas, for example, the non-active area 501 in FIG. 6a
between active optic sectors 500, 510, the above-described symmetry
principle is applied by providing an active optic sector 590 in a
position diametrically opposite the said non-active area 501.
Therefore, detection of light energy detected in the active optic
sector 590 is effectively detecting light energy incident on the
non-active area 501 between sectors 500, 510. In order to have an
active optic sector positioned diametrically opposite a non-active
area, two of the active optic sectors, e.g. , sectors 550, 560 are
positioned adjacent each other without any significant intervening
non-active area, so the diametrically opposite non-active area 631
is twice as big as other non-active areas. Therefore, according to
the above-described symmetry principle, substantially all light
energy 34 of FT optic pattern 32 (FIG. 5) is detectable by the
sixteen 11.25.degree. active optic sectors 500, 510, 520, 530, 540,
550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650.
[0068] Returning now to FIG. 6a, vertical angular orientation is
arbitrarily designated as 0.degree., so horizontal angular
orientation is at 90.degree.. Each active optic sector 500, 510,
520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640,
650 is about 11.25.degree.. Active optic sectors from sector 640
clockwise to sector 550 are each separated by respective non-active
areas 641, 651, 501, 511, 521, 531, 541 of 11.25.degree..
Therefore, each active optic sector from sector 560 clockwise to
sector 630 is positioned diametrically opposite a respective
non-active area 561, 571, 581, 591, 601, 611, 621. Therefore, to
detect all the light energy distribution in the FT optic pattern 32
(FIG. 4) incident on the active area 54 can be detected in
11.25.degree. intervals by the 11.25.degree. sectors 500, 510, 520,
503, 504, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650
positioned as described above.
[0069] For example, light energy characteristic of that incident on
both the vertical 11.25.degree. sector 500 centered at 0.degree. as
well as on the non-active area 581 centered at 180.degree. can be
detected by effectively activating the active optical segments 502,
504, 506, 508 of sector 500. Light energy characteristic of that
incident on the 11.25.degree. sector 590 centered at 191.25.degree.
as well as on the non-active area 501 centered at 11.25.degree. can
be detected effectively by activating the active optic segments of
sector 590, because the active optic sector 590 is centered
diametrically opposite the non-active area of 11.25.degree.. Light
energy characteristic of that incident on either the 11.25.degree.
sector 510 centered at 22.5.degree. or the non-active area 591
centered at 202.5.degree. can be detected by activating the active
optic segments of sector 510. Light energy characteristic of that
incident on either the 11.25.degree. non-active area centered at
33.75.degree. or active sector 600 centered at 213.75.degree. can
be detected by activating the active optic segments of sector 600,
which is centered diametrically opposite 33.75.degree. at
213.75.degree.. Light energy characteristic of that incident on
either the 11.25.degree. sector 520 centered at 45.degree. or
non-active area 601 centered at 225.degree. can be detected by
activating the active optic segments of sector 520. Light energy
characteristic of that incident on either the 11.25.degree.
non-active area 521 centered at 56.25.degree. or the active sector
610 centered at 236.25.degree. can be detected by activating the
active optic segments of sector 610, which is centered
diametrically opposite 56.25.degree. at 256.25.degree.. Light
energy characteristic of that incident on either the 11.25.degree.
sector 530 centered at 67.5.degree. or the non-active area 611
centered at 247.5.degree. can be detected by activating the active
optic segments of sector 530. Light energy characteristic of that
incident on either the 11.25.degree. non-active area 531 centered
at 78.75.degree. or active sector 620 centered at 258.75.degree.
can be detected by activating the active optic segments of sector
620, which is centered diametrically opposite 78.75.degree. at
258.75.degree.. Light energy characteristic of that incident on
either the 11.25.degree. sector 540 centered at 90.degree. or
non-active area 621 centered at 270.degree. can be detected by
activating the active optic segments of sector 540. Light energy
characteristic of that incident on either the 11.25.degree.
non-active area 541 centered at 101.25.degree. or the active sector
630 centered at 281.25.degree. can be detected by activating the
active optic segments of sector 630, which is centered
diametrically opposite 101.25.degree. at 281.25.degree.. Light
energy characteristic of that incident on either the 11.25.degree.
sector 550 centered at 112.5.degree. the diametrically opposite
portion of non-active area 631 that is centered at 292.5.degree.
can be detected by activating the active optic segments of sector
550. Light energy characteristic of that incident on the
11.25.degree. sector 560 centered at 123.75.degree.. The
diametrically opposite portion of non-active area 631 that is
centered at 303.75.degree. can be detected by activating the active
optic segments of sector 560. Light energy characteristic of that
incident on the 11.25.degree. non-active area 561 centered at
135.degree. or active sector 640 centered at 315.degree. can be
detected by activating the active optic segments of sector 640,
which is centered diametrically opposite 135.degree. at
315.degree.. Light energy characteristic of that incident on the
11.25.degree. sector 570 centered at 146.25.degree. or non-active
area 641 centered at 326.25.degree. can be detected by activating
the active optic segments of sector 570. Light energy
characteristic of that incident on the 11.25.degree. non-active
area 571 centered at 157.5.degree. or active sector 650 centered at
337.5.degree. can be detected by activating the active optic
segments of sector 650, which is centered diametrically opposite
157.5.degree. at 337.5.degree.. Finally, light energy
characteristic of that incident on the 11.25.degree. sectors 580
centered at 168.75.degree. or non-active area 651 centered at
348.75.degree. can be detected by activating the active optic
segments of sector 580.
[0070] While it would be unnecessarily cumbersome to illustrate and
describe the shape detecting and characterizing functionality of
all the active optic segments of all the sectors 500, 510, 520,
530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, it
maybe helpful for an understanding of the invention to illustrate
and describe the functionality and results of activating several
representative examples of the active optic segments in the active
optic area 54. Therefore, FIG. 6a illustrates activation of the
outer segment 508 of the active optic sector 500 by depicting bands
of light energy 34 from the FT optic pattern 32 that are incident
on and reflected by the outer segment 508. These bands of light
energy 34, which are dispersed fartherest radially outward in the
vertical direction in the FT optic pattern 32, emanated originally
from, and correspond to, substantially vertically oriented lines,
edges, features, or details in the image 12' that have a higher
spatial frequency, such as the substantially vertical lines of the
bumper and grill parts 35 in FIG. 6b. As explained above, the light
energy 34 from the more intricate or closely spaced vertical parts
or lines 66 (i.e., higher spatial frequency), such as those in the
front bumper and grill portion 35 of image 12', are dispersed
farther radially outward from the optical center or axis 40, thus
detectable by activating outer segments 506, 508 of vertical sector
500, while the light energy 34 from the less intricate, more
isolated and semi-isolated or farther spaced apart vertical parts,
edges, or lines (i.e., lower spatial frequency), such as the
substantially vertical parts or lines 66' in the trunk and rear
bumper portions of the image 12' in FIG. 6b, are dispersed not so
far radially from the optical center or axis 40 and would be more
detectable by inner segments 502, 504. The intensity of the light
energy 34 in those respective dispersion bands, as explained above,
depends on the brightness of the corresponding respective vertical
features 35, 66, 66' in the image 12'. Again, the central portion
41 of the active optic area 54 can be ignored, if desired, because
the light energy 54 in and near the center or axis 40 of the
Fourier transform 32 (FIG. 5) emanates from features in image 12'
with very low or virtually no spatial frequencies, such as the
overall brightness of the image, which do very little, if anything,
to define shapes. On the other hand, as also explained above, the
center portion 41 can be fabricated as an active optic component to
capture and reflect the light energy incident on the center portion
41 to the detector 80 as a measure of overall brightness, which may
be useful in calibrating, adjusting brightness of the source light
25(s) (FIG. 5), calibrating intensity (I) measurements of sensors
84 in detector 80, and the like.
[0071] The light energy bands 34, when reflected by the activated
outer segment 508, are filtered through the polarizing beam
splitter 70 and projected in the filtered optic pattern 60, which
is comprised primary of vertical lines or bands 62 of light energy
illustrated diagrammatically in FIG. 6c, to the photodetector 80
(FIG. 5). As discussed above, the light energy in the filtered
optic pattern 60 is detected by the light sensors 84 in detector
array 82. The intensity (I) of light energy on each sensor 84 is
recorded along with the sensor (pixel) location, preferably by x-y
coordinates, and the angular orientation (R) of the sector 500. The
radial position or scale (S) of the activated segment 508 is also
recorded, for example, as RIXSe1 values described above. These
values can be stored in a database 102 in association with
information about the characterized image 12, such as image
identification (ID), source location (URL, database address, etc.)
of the image 12, digital format, resolution, colors, texture,
shape, subject matter category, and the like.
[0072] To illustrate further, the near inner segment 504 of active
optic sector 500 is shown in FIG. 7a as being selected to rotate
plane of polarization of selected portions of the light energy
bands 34 from the FT optic pattern 32 for isolation by the
polarizing beam splitter 70 and then detection by the photodetector
80. This near inner segment 504 is also in the vertically oriented
sector 500, but it is positioned or scaled radially closer to the
optic axis 40 than the outer segment 508, which was activated in
the previous example. Therefore, this near inner segment 504, when
activated, captures light energy 34 in the FT optic pattern 32 that
also corresponds to vertical lines, edges, etc. , of the image 12',
but to such lines, edges, etc. , of lesser spatial frequency than
those selected by the outer segment 508. For example, instead of
the closely spaced, vertically oriented bumper and grill parts 35,
the light energy 34 from the FT optic pattern 32 selected by the
near inner segment 504 may be more characteristic of the more
spatially semi-isolated vertical edge 66' of the trunk lid and
other vertical lines and edges 66 of similar semi-isolation in the
automobile image 12' in FIG. 6b. Therefore, the light energy bands
62 in the resulting filtered beam 61(s), as shown in optic pattern
60 in FIG. 8c, are characteristic of such vertical shape content
66, 66' in the image 12'.
[0073] Another example angular orientation of light energy 34 from
the FT optic pattern 32 is illustrated by FIGS. 8a-c. The near
outer segment 526 in this example is activated to capture light
from lines, edges, or features extending radially at an angular
orientation of 45.degree. from vertical. Such light energy 34 is
characteristic of lines, edges, or features in the image 12' that
extend at about 45.degree. and that have some spatial frequency,
i.e., are not isolated, such as, perhaps, the window post and roof
support 67 in FIG. 8b. Such 45.degree. oriented lines in the image
12' with even less spatial frequency, i.e., even more isolated, for
example, the portions of the fender and hood edges 67' might be
captured more by the near inner segment 524 or inner segment 522,
although it is possible that some of such light energy could also
be captured by near outer segment 506. The reflected and filtered
beam 61(s) with the optical pattern 60 for these 45.degree. angular
oriented shape contents have bands 62 of the light energy oriented
at about 45.degree., as illustrated diagrammatically in FIG. 8c.
Such light energy bands 62 are detected by sensors 84 for
photodetector 80 (FIG. 5) and are recorded and stored as
characteristic of the spatial frequency of 45.degree.-oriented
shape content of the image 12'.
[0074] Capture and detection of horizontal portions of lines,
edges, and features 68, 68' of the image 12' is accomplished by
activation of one or more segments 542, 544, 546, 548 of Horizontal
sector 540, which is oriented 90.degree. from the vertical
0.degree.. The portion of the light energy 34 that is reflected by
any activated segment 542, 544, 546, 548 of the horizontal sector
540 is characteristic of all of the substantially horizontal
features, parts, and lines 68 of the image 12', as shown in FIG.
9b. Some curved features, parts, or lines in the image 12' have
portions or line segments 68' that are also substantially
horizontal, so those horizontal portions or line segments 68' also
contribute to the light energy 34 that gets reflected by the
horizontal sector 540 in FIG. 9a. The bands 62 of light energy in
the filtered pattern 60, shown in FIG. 9c, resulting from the
horizontal orientation of an activated segment 542, 544, 546, 548
in FIG. 9a, are also oriented substantially horizontal and are
indicative of some or all of the shape characteristics 68, 68' of
image 12' that are oriented substantially horizontal. Again, the
inner segments 542, 544 are activated to detect light energy bands
34 from the FT optic pattern 32 that are dispersed closer to the
optic axis 40, thus are characteristic of lower spatial frequency,
horizontal shape content of the image 12', while higher spatial
frequency, horizontal shape content can be detected by activating
the outer segments 546, 548 of the horizontal sector 540. Thus,
detection of the light energy bands 62 in FIG. 9c by detector array
82 (FIG. 5) facilitates encoding and recording of the horizontal
shape characteristics of the image 12', as was described above.
[0075] One more example activated segment 598 in sector 590, is
illustrated in FIG. 10a to describe the symmetric light energy
detection feature described above. As explained above, the light
energy bands 34 of the FT optic pattern 32 that are incident on the
non-active area between the active optic sectors 500, 510 are
symmetric with the diametrically opposite light energy bands 34,
which are incident on the active optic segments 529, 594, 569, 598
in sector 590. Therefore, activation of a segment, for example,
outer segment 598, as illustrated in FIG. 10a, will enable
effective detection of the diametrically opposite, equivalent light
energy 34 that is incident between the segments 508, 518 of
respective sectors 500, 510. Likewise, activation of any other
segment 592, 594, 596 enables effective detection of other
diametrically opposite portions of light energy that is incident in
the non-active area 501 between active sectors 500 and 510.
Therefore, detecting light energy 34 incident on the sector 590,
which is centered at 191.25.degree. in the example of FIG. 10a, is
the equivalent of detecting light energy 34 that is incident on the
non-active area 501 centered at 11.25.degree.. The opposite also
holds, i.e., detection of light energy 34 incident on the vertical
sector 500, as illustrated in FIGS. 6a and 7a and described above,
is the equivalent to detecting light energy from the FT optic
pattern 32 that is incident on the non-active area 581 between
active sectors 580 and 590.
[0076] Referring again to FIGS. 10a-c, the light energy 34 detected
in the sector 590 corresponds to shape content 69, such as lines,
edges, portions of curves, and the like in the image 12' that are
oriented substantially at about 191.25.degree., which, being
linear, can also be expressed as oriented at about 11.25.degree..
The light energy bands 62 in the reflected and filtered optic
pattern 60 also have that same angular orientation, which is
characteristic of the linear shape content of the image 12' that
has that angular orientation and that has higher spatial frequency
if reflected by outer segments 596, 598 or lower spatial frequency
if reflected by inner segments 592, 594. the optic patterns 60
resulting from such various reflected portions of the FT optic
pattern 32 are detected by the sensors 84 in detector array 82 for
recording and storage, as described above.
[0077] It should be clear by now that any particular angular
orientation R of segments of sectors in the active optic area 54
will allow detection of all the shape characteristics of image 12'
that have substantially that same angular orientation R. It should
also be clear that radial outward spacing or scale (S) of the
segments relates to spatial frequency of such shape
characteristics. Thus, all of the shape characteristics of the
image 12' can be detected by detecting the bands 62 of the
respective filtered patterns 60 with the segments at all angular
orientations. However, as mentioned above, it is sufficient for
most purposes to detect some, preferably most, but not necessarily
all, of the shape characteristics of the image 12' by choosing to
detect the light energy bands 34 of filtered patterns 60 at certain
selected increments of or angular orientation or rotation R.
Obviously, the bigger the increments of angular orientation of the
sectors where light energy bands 34 are detected, the less precise
the detected shape characteristics or contents of the image 12'
will be. On the other hand, the smaller the increments of angular
orientation, the more data that will have to be processed.
Therefore, when selecting the angular increments of sectors at
which light energy bands 34 will be detected and recorded, it may
be desirable to strike some balance between preciseness of shape
characteristics needed or wanted and the speed and efficiency of
data processing and storage required to handle such preciseness.
For example, but not for limitation, it is believed that detection
and recording of the shape characteristics at angular increments of
in a range of about 5 to 20 degrees, preferably about
11.25-degrees, will be adequate for most purposes. Also, the
angular area of detection can be varied. For example, even if
active optic sectors are oriented to detect shape characteristics
at angular increments of 11.25.degree., the active optic areas
could be narrow, such as in a range of 3.degree. to 8.degree., more
or less, which would filter out some of the optic energy from the
FT optic pattern 32 between the sectors. However, such loss of
light energy from non-active areas between sectors or other
radially extending sensors, as described elsewhere in this
specification, may not be detrimental shape characterization by
this invention, depending on specific applications of the
technology to particular problems or goals.
[0078] Instead of the radially extending, wedge-shaped active optic
sectors and segments of sectors described above, an alternate
configuration can be comprised of radially extending,
rectangular-shaped active optic modulators as illustrated
diagrammatically in FIG. 1. These rectangular-shaped modulators
500', 510', 520', 530', 540', 550', 560', 570', 580', 590', 600',
610', 620', 630', 640', 650' can be at the same or different
angular orientations as the wedge-shaped sectors described above,
and each angular orientation can comprise several rectangular,
active optic segments, such as segments 502', 504', 506', 508' of
the modulator 500'. This arrangement does not capture as much of
the light energy of an incident FT optic pattern 32 (FIG. 5) as the
wedge-shaped segments and sectors described above, but shape
resolution may be greater.
[0079] Another, albeit less efficient embodiment, is illustrated in
FIG. 12, where the desired sectors and segments, which are shown in
phantom lines, can be formed by activating selected groups of light
modulator elements 702 in a pixel array 700 type of spatial light
modulator simultaneously. For example, a virtual outer segment 508"
of a vertical sector 500" can be activated by activating
simultaneously a segment group 508" of the light modulator pixel
elements 602. While there are versatility advantages to this type
of implementation, such advantages may be outweighed by the
complexity and cost as compared to the simpler configurations
described above.
[0080] While the reflective spatial light modulator structure
described above in connection with the cross-sectional view of FIG.
4 may be applicable to all of the segmented radial SLM 50
configurations described above, an alternative transmissive spatial
light modulator structure 50' illustrated in FIG. 13 could also be
used with each of the configurations. In this embodiment 50', the
metal reflective layers 186, 188 are replaced by transparent
conducting layers 186', 188', such as indium tin oxide (ITO) or any
of a number of other well-known transparent conducting materials.
Therefore, incident 27(p) may or may not have its plane of
polarization rotated, depending on whether a voltage V+ is applied
to either layer 186' or 188', but, instead of being reflected, the
light is transmitted through the device 50' to emerge as light
energy 61(s) or 61(p), as indicated in FIG. 13. this device is
mounted around its periphery in a base 56, so the base 56 does not
interfere with the light 61(s) and 61(p) propagation. A different
liquid crystal material 180' and/or a different thickness of liquid
crystal material than the liquid crystal material 180 for the FIG.
4 embodiment would be required, since the light passes only once
through the liquid crystal material 180'. However, such materials
and their applications are readily available and well-known in the
art and can be implemented by persons skilled in the art, once the
understand the principles of this invention. Also, since the light
61 (s) is transmitted rather than reflected, the polarizing beam
splitter 70 (FIG. 5) would also have to be positioned behind the
segmented radial SLM 50' of FIG. 13 instead of in front of it.
However, this modification could also be implemented quite easily
by persons skilled in the art, thus is not shown explicitly in FIG.
5.
[0081] The accuracy, versatility, and efficiency of shape
characterizing, processing, storing, searching, comparing, and
matching images according to this invention can be enhanced by some
pre-processing of the images 12, 14, . . . , n when creating the
optical patterns for the images 12', 14', . . . , n' at the SLM 26
in FIG. 5. One particularly beneficial method of such
pre-processing is "ghosting" the image to allow more light energy
into the optic pattern 12', thus also allowing more light energy
into the FT optic pattern 32.
[0082] With reference now to FIGS. 14a-c, the ghosting process of
this invention is illustrated first with an image content of a
simple dot, such as a typed period 600, which is illustrated as
greatly enlarged in FIG. 14a. The computer 20 (FIG. 5) or other
microprocessor can first create an image of only the edge 602 of
the dot 600, as illustrated in FIG. 14b. Myriad edge-finding
software programs are available commercially to perform such
edge-finding tasks, such as Labview IMAQ.TM. available from
National Instrument Corporation, of 11500 Mopac Expressway, Austin,
Tex. More complex images 12, 14, . . . , n would, of course, have
more edge content. Elimination of non-edge content of the images
12, 14, . . . , n does not degrade the shape characterizing
function or performance of this invention, because the edges define
the shape characteristics and produce the detectable FT optic
patterns 32. As was explained above, plain, uniform, unchanging
portions of images, such as the side panel 36 of the automobile in
image 12' or the clear blue sky in a landscape picture 14 do not
contribute significant detectable shape content to such images. As
also explained above, light energy from such plain, uniform,
unchanging portions of images tends to focus on or very near the
optic axis 40 in Fourier transform optic patterns 32, thus would be
incident primarily on the center section 41 of the segmented radial
SLM 50 (see FIG. 2) and is either not detected at all or detected
only to determine background brightness of the image, as explained
above.
[0083] After the image 600 is converted to an optic pattern of the
edge content 602 of the image 600, as illustrated in FIG. 14b, it
is ghosted by creating a plurality of ghost images 602 the edge
content 602. For example, as illustrated in FIG. 14c, a plurality
of ghost images 602.sub.A, 602.sub.B 602.sub.C are created and
added to the optic pattern of the edge image 602. In this example,
a first set of eight ghost images 602.sub.A is added a first radial
distance r.sub.1 outward from the original edge image 602 at
45.degree. angular increments. A second set of eight more ghost
images 602.sub.B are added another radial distance r.sub.2 outward
from the ghost images 602.sub.A and at 45.degree. angular
increments, and a third set of eight ghost images 602.sub.C are
added another radial distance r.sub.3 outward and at 45.degree.
increments. Each of the ghost images 602.sub.A, 602.sub.B,
602.sub.C have the same shape and are of the same size as the
original edge image 602. Therefore, while there is more light
energy and more spatial frequency in the ghosted image 602' of FIG.
14c than in the edge image 602 of FIG. 14b, there is no new shape
content. Consequently, there will be both a wider radial
dispersement and increased intensity of light energy 34 in the FT
optic pattern 32 (FIG. 5), which can be detected with the segmented
radial SLM 50 and detector 80. the higher intensity light energy
makes it easier for the sensors 84 in detector 80 to detect the
light energy diverted by the segmented radial SLM 50 to the
detector 80
[0084] The wider radial dispersion of light energy in FT optic
pattern 32 due to the higher spatial frequency content in the
ghosted image 602' of FIG. 14c, as compared to the non-ghosted
image 602 of FIG. 14b, would also make the recorded pixels of
detected light energy by the sensors 84 (FIG. 5) somewhat less
precise, thus less unique to the image 600 or 602 than would be
obtained by producing the image 600 or 602 on the SLM 26 instead of
the ghosted image 602'. However, this decrease in resolution
capability can actually be turned to an advantage for search and
comparison applications, where near matches as well as matches are
desired. As illustrated in FIG. 14c, the initial edge image pattern
602 is bright, the nearest ring of ghost edge images 602.sub.A is
less bright, the next ring of ghost edge images 602.sub.B is even
less bright, and the outermost ring of ghost edge images 602.sub.C
is less bright yet. However, the ghost images 602.sub.A, 602.sub.B,
602.sub.C increase the spatial frequency of the image 602', thus
cause more radial dispersion of the light energy bands 34 in the FT
optic pattern 32, so the portions of the light energy bands 34 that
originate from the initial edge image 602 in the center of the
ghosted pattern 602' are brighter, i.e., more intense, than
portions of the light energy bands 34 that originate from the ghost
images 602.sub.A, 602.sub.B, 602.sub.C. Therefore, while more
sensors 84 of the detector array 82 will detect light energy
reflected by the segmented radial SLM 50 to the detector 80 for a
ghosted image 602', the sensors 84 that sense the highest intensity
(I) light energy will be the sensors 84 that correspond to the
initial edge image 602, and those intensities can be recorded and
stored for future access, analysis, searching, matching, and/or
retrieving, as described above. The lesser intensities detected by
other sensors 84 for light energy emanating from the nearest ring
of ghost images 602.sub.A are also recorded and stored, as are
those even lesser light intensities emanating from the other rings
of ghost images 602.sub.B, 602.sub.C sensed by still other sensors
84. Therefore, in a search and matching process with other images,
matches to the brightest or highest intensities of both images
would indicate the highest probability that the respective images
are the same. If no such match can be found to the brightest or
highest intensity pixels, RIXels, or other records of optic
patterns that are characterized as described above, then
comparisons to lesser intensities corresponding to ghost images
602.sub.A, 602.sub.B, 603.sub.C can be attempted to find near
matches.
[0085] The ghosting process is quite simple and can be scaled to
achieve a desired result. Essentially, a software program can
simply be applied to reproduce each pixel of an image at selected
locations at selected distances and at selected angular
orientations in relation to such pixel, as illustrated in the
simple example of the dot 600 in FIGS. 14a-c. An example of this
ghosting process in a slightly more complex image 610 in the shape
of a house is illustrated in FIGS. 15a-c. The edges of the uniform
or featureless areas of the house image 610 are found and produced
in an edge image 612,, which maintains the shape content of the
image 610, as explained above. Then the ghosting process described
above is applied to the edge image 612, as illustrated in FIG. 14c,
to create ghost images 612.sub.A, 612.sub.B, 612.sub.C at selected
distances, angular orientations, and decreasing brightnesses the
farther the ghost images 612.sub.A, 612.sub.B, 612.sub.C are from
the initial edge image 612.
[0086] The ghosting process of this invention can also be applied
to images for which edges have not been found or produced, as
described above. However, more pixel processing by the computer 20
or other processor would be required, and resulting shape
resolution may not be as sharp.
[0087] Since these and numerous other modifications and
combinations of the above-described method and embodiments will
readily occur to those skilled in the art, it is not desired to
limit the invention to the exact construction and process shown and
described above. For example, Accordingly, resort may be made to
all suitable modifications and equivalents that fall within the
scope of the invention as defined by the claims which follow. The
words "comprise," "comprises," "comprising," "include,"
"including," and "includes" when used in this specification and in
the following claims are intended to specify the presence of stated
features or steps, but they do not preclude the presence or
addition of one or more other features, steps, or groups
thereof.
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