U.S. patent application number 15/637567 was filed with the patent office on 2017-10-19 for machine vision verification.
The applicant listed for this patent is Entrust Datacard Corporation. Invention is credited to Cory WOOLDRIDGE.
Application Number | 20170300747 15/637567 |
Document ID | / |
Family ID | 50547236 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170300747 |
Kind Code |
A1 |
WOOLDRIDGE; Cory |
October 19, 2017 |
MACHINE VISION VERIFICATION
Abstract
Embodiments of systems and methods for directly reading and
verifying characters on a personalized document, are provided. A
surface of the personalized document is illuminated independently
or simultaneously by first and second light sources. The first
light source has a ring shape, surrounds the personalized document
in 360 degree, and transmits a grazing incident light to illuminate
the surface of the personalized document. An incident light from
the second light source is reflected by a beam splitter and
illuminates the surface of the personalized document in a direction
generally perpendicular to the surface. Light reflected from the
surface of the personalized document in a direction generally
perpendicular to the surface thereof is collected by a camera.
Inventors: |
WOOLDRIDGE; Cory; (Shakopee,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entrust Datacard Corporation |
Shakopee |
MN |
US |
|
|
Family ID: |
50547236 |
Appl. No.: |
15/637567 |
Filed: |
June 29, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14068407 |
Oct 31, 2013 |
9727781 |
|
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15637567 |
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61720521 |
Oct 31, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G07D 7/00 20130101; G06K
9/2036 20130101; H04N 1/00 20130101; G06K 9/00463 20130101 |
International
Class: |
G06K 9/00 20060101
G06K009/00; G06K 9/20 20060101 G06K009/20; G07D 7/00 20060101
G07D007/00; H04N 1/00 20060101 H04N001/00 |
Claims
1. A method of directly reading and verifying a character on a
surface of a personalized document, comprising: illuminating the
surface of the personalized document including the character using
a first light source that surrounds the personalized document and
that transmits a grazing incident light onto the surface including
the character so that first light reflects from the surface
including the character, and collecting the first light reflected
from the surface including the character to capture a first image
of the character; illuminating the surface of the personalized
document including the character using a second light source that
transmits incident light onto the surface including the character
so that second light reflects from the surface including the
character, and collecting the second light reflected from the
surface including the character to capture a second image of the
character; and verifying the character by a combination of the
first and second captured images.
2. The method of claim 1, wherein the grazing incident light from
the first light source forms an angle of about 25.degree. with
respect to the surface of the personalized document.
3. The method of claim 1, wherein the first light source has a ring
shape.
4. The method of claim 1, wherein the incident light from the
second light source is reflected by a beam splitter and illuminates
the surface including the character in a direction generally
perpendicular to the surface.
5. The method of claim 4, wherein the first, second and third
images are captured using a camera, and further comprising using a
mirror that is positioned to direct the first, second and third
light reflected from the surface including the character to the
camera.
6. The method of claim 1, wherein the character comprises an
embossed character.
7. The method of claim 1, wherein the document is a plastic
card.
8. The method of claim 1, further comprising: simultaneously
illuminating the surface including the character using the first
light source and the second light source so that the grazing
incident light from the first light source and the incident light
from the second light source are simultaneously transmitted onto
the surface including the character so that third light reflects
from the surface including the character, and collecting the third
light reflected from the surface including the character to capture
a third image of the character; and verifying the character by
combining the first, second and third captured images.
Description
FIELD OF TECHNOLOGY
[0001] The embodiments disclosed herein relate generally to machine
vision verification, more particularly to a vision verification
system for characters or symbols on a personalized document.
BACKGROUND
[0002] In certain applications, embossed and/or indented
characters, such as lines, numbers, letters, symbols, etc., on a
personalized document, e.g., a credit card, need to be verified or
recognized. Prior approaches used include imaging a card using a
digital camera and an illumination source such as a Cloudy Day
Illuminator (CDI) so that the embossed characters thereof can be
verified or recognized by digitizing the image of the embossed
card.
SUMMARY
[0003] The embodiments described herein relate to systems and
methods for directly reading and verifying character(s) on a
personalized document such as, for example, a credit card, an
identification card, a gift card, a passport, etc. The embodiments
provide systems and methods to illuminate the character(s) on the
personalized document and directly capture an image of the
character(s).
[0004] In one embodiment, the light reflected from a perimeter of
the characters and that reflected from an inner portion of the
characters surrounded by the perimeter, in a direction generally
perpendicular to the surface of the personalized document, are
different in brightness to provide a contrast. An image of the
characters is captured by collecting the reflected light in the
direction generally perpendicular to the surface of the
personalized document. The captured image is then used to verify
and/or recognize the characters on the personalized document. The
characters include, for example, lines, numbers, letters, symbols,
Braille, etc.
[0005] The embodiments described herein utilize at least one light
source for illuminating the front side and/or the back side of the
personalized document. The embodiments can reliably verify and/or
recognize characters on a personalized document even if there are
reflections caused by, for example, a metallic background of the
personalized document, and/or characters having similar color as
the background thereof.
[0006] The embodiments described herein can reliably verify and/or
recognize any character on a personalized document that has a
character size of, for example, 7 or 10 characters per inch (CPI)
or even smaller characters. The conventional approaches using CDI
may not reliably verify characters having a size of 10 CPI or
less.
[0007] In addition, the embodiments can determine and analyze
location and spacing of the characters to determine whether they
meet standards, for example, the ISO 7811-1 standard.
[0008] In one embodiment, a vision verification system for directly
reading and verifying characters on a personalized document
includes at least one light source for illuminating a surface of
the personalized document, and a camera for capturing an image of
the characters on the surface of the personalized document. The
light source is disposed with respect to the personalized document
so that only light reflected from the surface of the personalized
document in a direction generally perpendicular to the surface
thereof is collected by the camera, and that the captured image
provides a contrast between the perimeter of the characters and an
inner portion of the characters defined by the perimeter.
[0009] In another embodiment, a method for directly reading and
verifying characters on a personalized document is provided. The
method includes illuminating a surface of the personalized
document, reflecting, from a perimeter of the characters, a first
amount of light in a direction generally perpendicular to the
surface of the personalized document, and reflecting, from an inner
portion of the characters, a second amount of light in the
direction generally perpendicular to the surface of the
personalized document. The second amount of light is brighter or
darker than the first amount of light to provide a contrast. The
reflected light is collected in the direction generally
perpendicular to the surface of the personalized document to
capture an image of the characters.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Referring now to the drawings in which like reference
numbers represent corresponding parts throughout.
[0011] FIG. 1a illustrates a side view of a machine vision
verification system, according to one embodiment.
[0012] FIG. 1b illustrates a die angle of an embossed character on
a card.
[0013] FIG. 2a illustrates an image of a portion of the front side
of a card with embossed characters when the card is illuminated by
a first light source, according to one embodiment.
[0014] FIG. 2b illustrates an image of the portion of the back side
of the card in FIG. 2a when the card is illuminated by the first
light source, according to one embodiment.
[0015] FIG. 3a illustrates an image of a portion of the front side
of a card with embossed Braille characters when the card is
illuminated by a first light source, according to one
embodiment.
[0016] FIG. 3b illustrates an image of the portion of the back side
of the card in FIG. 3a when the card is illuminated by the first
light source, according to one embodiment.
[0017] FIG. 4a illustrates an image of a portion of the front side
of a card with embossed characters when the card is illuminated by
a second light source, according to one embodiment.
[0018] FIG. 4b illustrates an image of the portion of the back side
of the card in FIG. 4a with embossed characters when the card is
illuminated by the second light source, according to one
embodiment.
[0019] FIG. 5 illustrates a combination of three images (a), (b)
and (c) used for verification.
[0020] FIG. 6 illustrates how to determine and analyze location
and/or spacing of characters on a card to determine whether the
characters meet the ISO 7811-1 standard
DETAILED DESCRIPTION
[0021] The embodiments described herein relate to systems and
methods for directly reading and verifying characters on a
personalized document such as, for example, a credit card, an
identification card, a gift card, a passport, etc. The embodiments
provide systems and methods to illuminate the characters on the
personalized document and directly capture an image of the
characters. The light reflected from a perimeter of the characters
and that reflected from an inner portion of the characters
surrounded by the perimeter, in a direction generally perpendicular
to the surface of the personalized document, are different in
brightness to provide a contrast. An image of the characters is
captured by collecting the reflected light in the direction
generally perpendicular to the surface of the personalized
document. The captured image is then used to verify and/or
recognize the characters on the personalized document. The
characters can include, for example, embossed or indented
characters, symbols, Braille, etc.
[0022] References are made to the accompanying drawings that form a
part hereof, and in which is shown by way of illustration of the
embodiments in which the methods and systems described herein may
be practiced. The term "personalized document" generally refers to
a document having a surface with character(s) thereon that can be
captured and recorded in an image. In one embodiment, the
personalized document can be a card such as, for example, a credit
card, an identification card, a gift card, etc. The card can
include a card substrate made of, for example, a plastic material
or other suitable materials. The card can also include embossed
characters, symbols, Braille, etc., on a surface of the card. When
embossing a character, a coloration material can be transferred
from a foil onto the character. The card can also include printed
material, a hologram(s), a magnetic stripe, an integrated circuit
chip, etc. The personalized document can also be a passport or
other travel document.
[0023] The term "embossed character" refers to a character that is
indented from one side of a card and raised above the opposite
surface of the card. The term "embossed character" also refers to a
character that is indented into one surface of a card without being
raised above the opposite surface.
[0024] The term "contrast" generally refers to the difference in
brightness and/or color that makes an object (or a representation
of the object in an image or display) distinguishable.
[0025] The term "camera" generally refers to a device that captures
and records images. The camera can be a monochrome digital camera,
a high resolution digital camera, or any suitable digital or
non-digital camera.
[0026] FIG. 1 illustrates a system 100 for directly reading and
verifying characters 107 on a surface of a card 106. The system 100
includes a box 110 that has a first side 112 and an opposite side
114, a second side 116 and an opposite side 118, and top and bottom
sides (not shown). The first side 112 and the opposite side 114 can
be open or light transmissive to allow light pass therethrough. The
card 106 is disposed facing an X axis, with a front surface 106a
facing the first side 112 of the box 110, facing a mirror 102
through the sides 112 and 114. The mirror 102 and a camera 101 are
mounted on a bracket 120 fixed on the box 110. The camera 101 has
an optical axis 101a generally parallel to a Y axis, or generally
parallel to the surface 106a of the card 106. An image of the card
106 is captured and recorded by the camera 101, via the reflection
of the mirror 102. In some embodiments, the camera 101 can face the
card 106 and the image of the card 106 can be directly captured and
recorded by the camera without the mirror 102. It is to be
understood that any suitable optical devices for helping the image
of the card to be captured by the camera 101 can be used.
[0027] A first light source 105 is mounted on a bracket 130 for
illuminating the card 106. The first light source 105 surrounds the
card 106. In the embodiment of FIG. 1, the first light source 105
has a circular shape. In some embodiments, the first light source
can have, for example, a square, polygon, octagon, multifaceted
shape, etc. The first light source 105 includes light-emitting
diodes (LEDs) that surround the card 106. That is, the LEDs are
disposed in a ring shape and each illuminate the surface of the
card 106 with grazing incident light so that a 360 degree
illumination is provided. The grazing incident light from the first
light source 105 forms an angle a with respect to the Y axis that
has a range from about 0.degree. to about 45.degree.. In the
illustrated embodiment, the angle a is about 25.degree..
[0028] A second light source 109 is disposed on the side 116 of the
box 110 for illuminating the card 106. The second light source 109
includes an array of LEDs that emit light through a diffuser plate
108 in a direction generally parallel to the Y axis. The diffused
light transmits to a beam splitter 103. The beam splitter 103 is
semitransparent and disposed about 45.degree. with respect to the
surface of the card 106. A portion of the diffused light is
reflected to illuminate the surface 106a of the card 106 in a
direction generally opposite the X axis. In one embodiment, about
50% of the diffused light can be reflected. The remaining portion
of the diffused light transmits through the beam splitter 103 and
is absorbed by the side 118. The side 118 includes a velvety felt
like material 104 disposed on the surface thereof to enhance the
light absorption. It is to be understood that the first and second
light sources can include any suitable light sources other than
LED. The light sources can be white light or monochromatic light
such as red, green or blue light, or any combinations thereof.
[0029] In the embodiment shown in FIG. 1, the characters 107 of the
card 106 include embossed characters that are indented from the
back surface 106b of the card 106 and raised above the front
surface 106a. The raised characters shown on the front surface 106a
and the corresponding recessed characters on the back surface 106b
are mirrored with each other. On the front surface 106a, the
characters 107 each include a perimeter that forms a slope rising
to an inner portion or top surface that is raised above the front
surface 106a. Correspondingly, on the back surface 106b, the
characters 107 each include a perimeter that forms a slope down to
an inner portion or bottom surface that is indented below the back
surface 106b. The slope forms a die angle of, for example, about
32.5.+-.0.5.degree. with respect to the front or back surface of
the card 106.
[0030] As shown in FIG. 1a, a die angle refers to a draft angle
.theta. when forming an embossed character 166 on a card 160 by,
for example, indenting the card 160 using a punch 150 having a
raised feature 154. The die angle is formed between a slope 164 of
the embossed character 166 and a surface normal 162. In one
embodiment, the magnitude of the draft angle .theta. can be about
33.degree.. However, is to be understood that the draft angle
.theta. can be values other than 33.degree. as long as the draft
angle helps to prevent the punch 150 and the card 160 from sticking
together when forming the embossed character 166. It is to be
understood that the slope 164 can be a curved surface leading
toward a surface 168 of the embossed character 166.
[0031] Returning to FIG. 1a, the first and second light sources
105, 109 can be used independently or simultaneously for
illuminating the characters 107 on the front surface 106a and/or
the back surface 106b of the card 106. FIG. 2a illustrates an image
206 of a portion of the front surface 106a of the card 106 captured
by the camera 101 when the front surface 106a faces the mirror 102
and the characters 107 on the front surface 106a are illuminated by
the first light source 105. The light from the first light source
105 can have an incident angle a, e.g., about 0-45.degree.. With
such an incident angle, the incident light on the inner portion or
top surface of the raised characters can be reflected away from the
direction generally perpendicular to the surface 106a, or reflected
away from the X axis, and the reflected light cannot be collected
by the camera 101. The front surface 106a of the card 106 that is a
background of the characters 107 can also reflect a significant
amount of the incident light away from the direction generally
parallel to the X axis, and the reflected light cannot be collected
by the camera 101. Therefore, there is more light reflected from
the perimeter of the characters in the direction generally parallel
to the X axis that can be collected by the camera 101 than that
reflected from the inner portion or top surface of the characters
and the background.
[0032] As shown in FIG. 2a, the image 206 includes a portion 210
that corresponds to the background on the front surface 106a of the
card 106, a portion 214 that corresponds to the perimeter of the
characters 107, and a portion 212 that corresponds to an inner
portion or top surface of the characters 107 that is surrounded by
the perimeter. The portion 214 corresponding to the perimeter is
much brighter than the portion 212 corresponding to the inner
portion of the raised characters. A strong contrast is formed
between the portion 212 and the portion 214, which can define an
image of the raised characters 107 on the front surface 106a of the
card 106.
[0033] FIG. 2b illustrates an image 206' of the portion of the back
surface 106b of the card 106 captured by the camera 101 when the
back surface 106b faces the mirror 102 and the characters 107 on
the back surface 106b is illuminated by the first light source 105.
The light from the first light source 105 has an incident angle a,
e.g., about 0-45.degree.. With such an incident angle, the
perimeter of the characters 107 is more illuminated than the
recessed inner portion or bottom surface of the characters 107 and
the remaining back surface 106b of the card 106 that is a
background.
[0034] As shown in FIG. 2b, the image 206' includes a portion 210'
that corresponds to the background on the back surface 106b of the
card 106, a portion 214' that corresponds to the perimeter of the
recessed characters 107, and a portion 212' that corresponds to an
inner portion or bottom surface of the recessed characters 107 that
is surrounded by the perimeter. The portion 214' corresponding to
the perimeter is brighter than the portion 212' corresponding to
the inner portion of the characters. A strong contrast is formed
between the portion 212' and the portion 214', which can define an
image of the recessed characters 107 on the back surface 106b of
the card 106.
[0035] In one embodiment, the characters 107 can include embossed
Braille characters. FIG. 3a illustrates an image 306 of the front
surface of the card 106 captured by the camera 101 when the raised
Braille characters are illuminated by the first light source 105.
FIG. 3b illustrates an image 306' of the back surface of the card
106 captured by the camera 101 when the recessed Braille characters
are illuminated by the first light source 105. In FIGS. 3a-b, the
perimeter of the Braille characters is brighter than the inner
portion of the characters that is defined or surrounded by the
perimeter when the Braille characters are illuminated by the first
light source 105.
[0036] The card 106 can also be illuminated by the second light
source 109 shown in FIG. 1a. FIG. 4a illustrates an image 406 of
the portion of the front surface 106a of the card 106 captured by
the camera 101 when the front surface 106a faces the mirror 102 and
the characters 107 on the front surface 106a are illuminated by the
second light source 109. The light from the second light source 109
is reflected by the beam splitter 103, and illuminates the front
surface of the card 106 in a direction generally perpendicular to
the surfaces 106a-b of the card 106, or a direction generally
opposite the X axis. The inner portion or top surface of the raised
characters 107 has a specular reflection of the incident light and
the reflected light can transmit back generally along the X axis
through the beam splitter 103, is reflected by the mirror 102, and
collected by the camera 101. In one embodiment, the embossed
characters can have a topping layer including colorant material(s)
that provides a specular-reflection surface. The perimeter of the
raised characters 107 with the die angle (e.g., about 32.degree.)
may not reflect the incident light back in the perpendicular
direction along the X axis and the reflected light may not be
collected by the camera 101. Thus, the inner portion or top surface
of the raised characters 107 appears brighter than the perimeter of
the characters 107. The background or the remaining portion of the
front surface 106a of the card 106 diffuses the incident light and
also appears darker than the inner portion of the raised
characters.
[0037] As shown in FIG. 4a, the image 406 includes a portion 410
that corresponds to the background on the front surface 106a of the
card 106, a portion 414 that corresponds to the perimeter of the
raised characters 107, and a portion 412 that corresponds to an
inner portion or top surface of the raised characters 107
surrounded by the perimeter. The portion 414 corresponding to the
perimeter is darker than the portion 412 corresponding to the inner
portion or top surface of the raised characters. A strong contrast
is formed between the portion 412 and the portion 414, which well
defines an image of the raised characters on the front surface of
the card 106.
[0038] FIG. 4b illustrates an image 406' of a portion of the back
surface 106b of the card 106 captured by the camera 101 when the
back surface 106b faces the mirror 102 and the characters 107 on
the back surface 106b are illuminated by the second light source
109. The image 406' includes a portion 410' that corresponds to the
background on the back surface 106b of the card 106, a portion 414'
that corresponds to the perimeter of the recessed characters 107,
and a portion 412' that corresponds to an inner portion or bottom
surface of the raised characters 107 surrounded by the perimeter.
The portion 414' corresponding to the perimeter is much darker than
the portion 412' corresponding to the inner portion or bottom
surface of the recessed characters. A strong contrast is formed
between the portion 412' and the portion 414', which can define an
image of the recessed characters 107 on the back surface of the
card 106.
[0039] As shown in FIGS. 2a and 4a, the images 206 and 406 are
captured when the portion of the front surface 106a of the card 106
is illuminated by the first light source 105 and the second light
source 109, respectively. The captured images 206 and 406 of the
characters 107 are complementary with each other. That is, the
perimeter of the characters is brighter than the inner portion of
the characters in the image 206, while the perimeter of the
characters is darker than the inner portion of the characters in
the image 406.
[0040] As shown in FIGS. 2b and 4b, the images 206' and 406' are
captured when the portion of the back surface 106b of the card 106
is illuminated by the first light source 105 and the second light
source 109, respectively. The captured images 206' and 406' of the
characters 107 are complementary with each other. That is, the
perimeter of the characters is brighter than the inner portion of
the characters in the image 206', while the perimeter of the
characters is darker than the inner portion of the character in the
image 406'.
[0041] In one embodiment, up to six images can be captured by
utilizing the first and second light sources 105, 109 independently
or simultaneously for illuminating the characters 107 on the front
and back surface of the card 106. The front surface 106a of the
card 106 can be illuminated respectively by the first light source
105, the second light source 109, and simultaneously by the first
and second light sources 105, 109, and three images can be captured
accordingly. The card 106 then can be flipped and three images can
be captured for the back surface 106b in the same manner.
[0042] In one embodiment, the three images for the front surface of
the card 106 can be combined as a mixture and analyzed by an
analysis tool to verify the characters.
[0043] In one embodiment, the three images for the back surface of
the card 106 can be combined as a mixture and analyzed by an
analysis tool to verify the characters.
[0044] It is to be understood that images of the card 106 can be
taken by any sequences and/or in any combinations. The captured
images are then analyzed as a mixture of combinations to verify the
characters 107. This provides the ability to analyze any
combination of the images in order to reach a desired threshold of
confidence that the character(s) is what is expected. The desired
threshold can be set at a value of 0 to 100. The higher the value
of the threshold, the higher the confidence level is in the
verification of the character(s). There can be a global threshold
setting for scoring combination of images and there can be
individual image threshold settings or a combination of global and
individual threshold settings.
[0045] FIG. 5 illustrates a combination of three images (a), (b)
and (c) that is used for verification. The three images (a), (b)
and (c) are taken from FIGS. 2a, 4 and 2b, respectively. The three
images (a), (b) and (c) are the images of the same character "8" on
the card 106. Portions 501, 501' and 501'' of the images (a), (b)
and (c) correspond to a side portion of the character "8". Portions
502, 502' and 502'' correspond to a bottom portion of the character
"8". In the image (a), the portion 501 shows a non-recognizable
contrast difference on the perimeter of the character, and the
portion 502 shows a recognizable contrast difference on the
perimeter of the character. The image (a) may be misread as a
character "3" by a user or a software analysis tool. In the image
(b), the portion 501' shows a recognizable contrast difference on
the perimeter of the character, and the portion 502' shows a
non-recognizable contrast difference on the perimeter of the
character. The images (a) and (b) can be combined to verify the
character "8". In the image (c), both the portions 501'' and 502''
show recognizable contrast difference on the perimeter of the
character. The image (c) can be used along with the images (a) and
(b) to confirm the verification and improve the confidence
level.
[0046] Images of a personalized document described herein, such as,
for example, the images shown in FIGS. 2a, 2b, 3a, 3b, 4a and 4b
can be used to determine and analyze location and spacing of the
characters to tell whether the characters meet standards. In one
embodiment, a character location analysis can be performed by, for
example, finding the center of each character in relationship to a
left edge and a bottom edge of the card. FIG. 6 illustrates how to
determine and analyze location of characters on a card to determine
whether the characters meet the ISO 7811-1 standard. An image 600
of the front side of the card includes an area 1 for an
identification number line and an area 2 for a name and address
area. The location of the characters in the area 1 and the area 2
can be determined and compared with requirements 610 of location
and tolerances in the ISO 7811-1 standard. The character spacing
analysis can be performed by, for example, finding the center of
each character in relationship to neighboring characters in the
area 1 and the area 2. A character spacing for 10 CPI can be, for
example, about 2.54.+-.0.15 mm. A characters spacing for 7 CPI can
be, for example, about 3.63.+-.0.15 mm.
[0047] With regard to the foregoing description, it is to be
understood that changes may be made in detail, especially in
matters of the construction materials employed and the shape, size
and arrangement of the parts without departing from the scope of
the present invention. It is intended that the specification and
depicted embodiment to be considered exemplary only, with a true
scope and spirit of the invention being indicated by the broad
meaning of the claims.
* * * * *