U.S. patent number 3,673,317 [Application Number 05/102,621] was granted by the patent office on 1972-06-27 for comparitive display of images in color.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to Paul G. Kennedy, George F. Newell.
United States Patent |
3,673,317 |
Newell , et al. |
June 27, 1972 |
COMPARITIVE DISPLAY OF IMAGES IN COLOR
Abstract
A system for the comparative display of video information
wherein first video signals, e.g. corresponding to a first X-ray
image, are compared with second video signals, e.g. corresponding
to a second X-ray image, are applied to a display, such as a color
television monitor, in such fashion that the difference between the
first and second images is displayed in color while the common
portion thereof are displayed in gray tones.
Inventors: |
Newell; George F. (Pittsburgh,
PA), Kennedy; Paul G. (Monroeville, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
22290795 |
Appl.
No.: |
05/102,621 |
Filed: |
December 30, 1970 |
Current U.S.
Class: |
348/29;
378/98.12; 386/224; 348/E9.028 |
Current CPC
Class: |
H04N
9/43 (20130101) |
Current International
Class: |
H04N
9/00 (20060101); H04N 9/43 (20060101); H04n
009/02 (); H04n 007/18 () |
Field of
Search: |
;178/5.2,5.4,6.6A,6.8,DIG.33 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Murray; Richard
Claims
What is claimed is:
1. In a system for the comparative display of video signals the
combination of:
means for providing first video signals corresponding to a first
video image and second video signals corresponding to a second
video image;
color display means including first, second and third primary color
means respectively responsive to video signals applied thereto for
effecting the display of the corresponding primary color on said
color display means; and
means for applying said first video signals to said first primary
color means and said second video signals to said second and third
primary color means so that the differences between said first and
second images are displayed by said color display means in color
and the common portions thereof are displayed in gray tones.
2. The combination of claim 1 wherein:
said means for providing includes recording means for recording
said first video signals on a first track thereof.
3. The combination of claim 2 wherein:
said recording means includes a second track for recording said
second video signals.
4. The combination of claim 1 wherein:
said means for providing include television camera means for
scanning said first and second images to provide said first and
second video signals, and
recording means for recording said first and second video signals
on first and second tracks respectively thereof,
said recording means includes a synchronizing track having
synchronizing signals prerecorded thereon for synchronizing said
television camera means, said recording means and said display
means.
5. The combination of claim 4 wherein said means for producing
includes
first switch means for selectively enabling the recording of
selected fields of video signals on respective tracks of said
recording means in response to said synchronizing signals, and
second switch means for selectively effecting the comparison of
video signals from selected tracks of said recording means.
6. The combination of claim 1 wherein:
said means for applying includes
means responsive to said first and second video signals for
applying said first video signal plus a portion of the difference
between said first and second video signals to said first primary
color means and said first video signals less a portion of the
difference between said first and second video signals to said
second and third primary color means respectively.
7. The combination of claim 6 wherein:
said means responsive to said first and second video signals
includes means for controlling the amplitude of the difference
between said first and second video signals so that the portion of
the difference is controlled in such a manner that the color
saturation of the displayed difference can be controlled.
8. The combination of claim 6 wherein:
said means responsive to said first and second video signals
includes first summing means for providing difference signals in
response to the difference between said first and second video
signals,
means for controlling the amplitude of said difference signals,
second summing means for adding said first video signals with said
amplitude controlled difference signals to supply said first
primary color means,
third summing means for differencing said first video signals and
said amplitude controlled difference signals to supply said second
primary color means, and
fourth summing means for differencing said first video signals and
said amplitude controlled difference signals to supply said third
primary color means.
Description
BACKGROUND OF THE INVENTION
The present invention relates to systems for displaying video
information and, more particularly, to such systems for the
comparative display of video information.
2. Description of the Prior Art
In X-ray analysis it is often necessary to compare an original
X-ray image with a subsequently taken X-ray image, for example,
taken after a dye has been inserted into the particular area of the
patient under surveillance. Photographic subtraction techniques
have been employed to accentuate the difference between the X-ray
picture by superimposing a positive and diapositive photograph so
that the common portions thereof are cancelled while differences
therebetween are fully reproduced. The image differencing may be
performed electronically without the registration problems of the
photographic technique wherein the X-ray images to be compared are
converted into video signals and are electrically subtracted from
one another to produce difference video signals which are displayed
on a television monitor. Complete cancellation of the common
portions of the image is, however, frequently undesirable since the
position of the difference portion with respect to the common
portions of the image is often required to be visible for
examination. It has been proposed to provide one image in one color
and the other image in another color and to add the images so that
the difference therebetween will appear in two colors while the
common portions thereof will be visible as another color. For
example, if one X-ray picture is reproduced in red and the other
one in green and the images are superimposed upon one another, the
differences therebetween will be shown in red and green; however,
the common portions thereof will be shown in yellow since the
addition of red and green produces yellow. Accordingly the spacial
relationship of the common portions with the different portions
would be readily ascertainable. It would be highly desirable if
electronic processing techniques could be employed rather than
photographic superposition requiring color photographs in at least
two colors and having the attendant registration problems.
Moreover, it would be highly advantageous if readily available
television monitoring equipment such as a color television receiver
could be employed for the display of the electronically processed
images.
SUMMARY OF THE INVENTION
Broadly, the present invention provides a system for the
comparative display of video information wherein the difference
between first and second images are displayed in color and the
common portions thereof are displayed in gray tones.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block-schematic diagram system of the present
invention; and
FIG. 2 is a block diagram showing a modification for inclusion in
the system of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, X-ray apparatus 10 supplies an X-ray image in
response to irradiation of a particular area of a patient under
surveillance. This X-ray image is supplied via an optical coupling
12 to the target of a television camera 14 which may comprise a
standard monochrome television camera which scans the X-ray image
at standard line and field repetition rates. The output of the
television camera 14 thus comprises video signals corresponding to
the scanned X-ray image. A magnetic disc recorder 16 is provided
which is driven at a predetermined speed by a motor drive 18. The
speed of rotation as determined by the motor drive 18 is selected
so that one complete rotation of the disc recorder 16 corresponds
to a predetermined number of vertical fields of scan of the camera
14. For example, if one frame (two fields) of video information are
desired to be recorded on a single circumferential track of the
disc recorder 16, the time period required for one complete
rotation of disc recorder 16 would be selected to be one thirtieth
of a second, that is, the time required for two fields at the
standard vertical rate of 60 Hz.
The disc recorder 16 includes a sync track 20 whereon synchronizing
signals are prerecorded. The function of the prerecorded
synchronizing signals is to provide a clock reference for the TV
camera 14, the record switch 22 and a color monitor 24. The
synchronizing signals on the sync track 20 are sensed by a playback
head 26 and applied to a sync processer 28 wherein horizontal and
vertical synchronizing information are generated at an output 30 in
response to the prerecorded synchronizing signals. The vertical and
horizontal synchronizing information is supplied to the TV camera
14 for controlling the horizontal and vertical scanning operation
thereof.
When it is desired to record a particular frame of video
information corresponding to a particular X-ray image under
consideration, an enable output is provided to the record switch
22. The record switch 22 is thus enabled in response to the next
vertical sync output 30 of the sync processer 28 to cause the
record switch 22 to translate the video input from the TV camera 14
to a first output 32 thereof for application to a record processor
34. The record processor 34 is operative to process the input video
signals thereto to a suitable form for recording, such as by well
known FM modulation techniques or other suitable recording
techniques. The processed video output appears at an output 36 of
the record processor 34 and is applied via a record head 38 for
recording on a track 40 of the disc recorder 16. Once two complete
fields, for example, of the video information from the TV camera 14
have been recorded on the track 40, the record switch 22 will
revert to its blocking state so that the output 32 thereof is
terminated.
When it is desired to record another frame of video information,
the record switch 22 will then be activated by the application of
an enable input thereto so that commencing with the first complete
field after the enable input the video output of the TV camera 14
will appear at a second output 42 of the record switch 22. The
output 42 will be processed in the record processor 34 and recorded
via a record head 44 on a track 46 of the disc recorder 16. One
complete frame of video information will therefore be recorded on
the track 46.
In response to the next enable input thereto the record switch 22
will provide a video output at its third output 48 for processing
in the record processor 34 and recording via a record head 50 on a
track 52 of the recorder disc 16. The recording process continues
as described above with a video output appearing at a fourth output
54 of record switch 22 after an enable input to the record switch
22 is provided. This output is recorded via a record head 56 on a
track 58 of the record disc 16. Thus a complete frame of video
information is recorded respectively on the tracks 40, 46, 52 and
58. For the purpose of simplicity of explanation only four
recording tracks and the sync track 20 are illustrated in FIG. 1.
However it should be understood that a greater or lesser number of
recording tracks could be employed as desired for the particular
implementation.
For medical diagnosis, such as involving angiography, an opaque
fluid is introduced into the blood vessels of the patient under
examination and X-ray pictures taken as the fluid progresses
through the vessels. The present system may be effectively used in
such examination. Just prior to the injection of the opaque fluid
into the patient an X-ray image would be recorded as described
above on the first recording track 40 of the disc recorder 16. At
various time increments after the introduction of the fluid into
the patient the record switch 22 would be enabled so that the X-ray
image at that instant in time would be recorded on subsequent
recording tracks of the disc recorder 16. Hence a complete record
of the fluid progression through the blood vessels of the patient
would be recorded and stored on the respective tracks of the disc
recorder 16. These various tracks would be available for later
analysis and comparison without the need for continuous radiation
of the patient by the X-ray apparatus 10.
The comparative display of the video information corresponding to
the recorder video images is accomplished as follows. Playback
heads 60, 62, 64 and 66, respectively, associated with recording
tracks 40, 46, 52 and 58 sense the processed video information
recorded on the respective tracks and apply this information to a
playback processor 68. The playback processor 68 converts the
recorded information to its original video form prior to processing
in record processor 34. For example, if the video information was
recorded on the respective tracks by FM modulation techniques, the
playback processor 68 would function as an FM demodulator for the
conversion of the recorded information to its video form prior to
recording.
The playback processor 68 provides four outputs 70, 72, 74 and 76
corresponding to the information recorded on the tracks 40, 46, 52
and 58, respectively. The outputs 70, 72, 74 and 76 are
respectively applied to four fixed contacts of a pair of switches
SA and SB. Thus the output 70 is applied to contacts 40A and 40B of
the switches SA and SB respectively; the output 72 to the contacts
46A and 46B; the output 74 to the contacts 52A and 52B; and the
output 76 to the contacts 58A and 58B. The switch SA is provided
with a movable contact MA and the switch SB with a movable contact
MB. Movable contacts MA and MB thus may sequentially engage the
fixed contacts of the switches SA and SB, respectively. The movable
arms MA and MB are operative independently of one another so that
different video information from the respective tracks 40, 46, 52
and 58 may be independently outputted by the switches SA and SB
from the respective output terminals TA and TB thereof. Hence, as
shown in FIG. 1, when the arm MA is connected to the fixed contact
40A, the output appearing at the terminal TA will be that
associated with the information previously recorded on the track
40. The arm MB of switch SB is shown in FIG. 1 connected to the
fixed contacts 46B so that the output appearing at the terminal TB
will be the information previously recorded on track 46.
The output from the terminal TA corresponding to the information
previously recorded on track 40 is supplied to a red R input of the
color monitor 24. The output appearing at the terminal TB of switch
SB corresponding to the previously recorded video information on
track 46 is supplied to both a green G and a B input of the color
monitor 24. The red, green and blue inputs of the color monitor 24
would comprise the red, green and blue guns of a standard three-gun
color picture tube. Suitable amplification of the video signals
appearing at the terminals TA and TB may be performed within the
color monitor prior to application to the respective color guns if
required.
As previously explained the color monitor 24 is synchronized to the
disc recorder 16 and the television camera 14 with synchronizing
information being provided to the monitor 24 from the sync
processor 28, which is responsive to synchronizing information
prerecorded on the sync track 20 of the disc recorder 16.
The information thus driving the red input of the color monitor is
the video information recorded on the track 40, which as discussed
above, may correspond to a reference X-ray image taken prior to the
injection of opaque fluid into the blood vessels of the patient.
The information applied to both the green and blue inputs of the
color monitor 24 corresponds to video information recorded on the
track 46 which may correspond to an X-ray image taken at a time
somewhat after the opaque fluid has been injected into the patient.
Since the common portions of the video signals corresponding to the
X-ray images are applied to all three of the inputs to the color
monitor 24, the common portions of the images will be produced in
monochrome, that is, as a normal black-grey-white background
picture defining the common portions of the X-ray images. The
difference between the images recorded on the tracks 40 and 46,
however, will be reproduced in color. The color reproduced and the
intensity of this color will depend upon the magnitude of the
difference between the X-ray images as recorded on the respective
tracks 40 and 46 and the direction of this difference.
For example, those portions of the image applied to the red input
which are less dark (less saturated) than the same portions of the
X-ray image applied to the blue-green input will be produced in a
shade of red. If the difference between the same portions of the
red and green-blue inputs is slight, the displayed picture from a
color monitor 24 will be produced as a pink or pastel shade. If, on
the other hand, the difference is large, the color reproduced for
the common difference portion would be an intense red. If the
difference between the two X-ray images is in the other direction,
that is, those portions that are applied to the red input which are
darker (more saturated) than the same portions applied to the
blue-green input would be reproduced by the color monitor 24 as
cyan color (blue + green). The intensity of the cyan color
reproduced would be dependent upon the magnitude of the difference
with the higher intensity cyan being indicative of a greater
difference.
The display of the color monitor 24 would thus be one wherein the
common portions of the original X-ray images as recorded on the
tracks 40 and 46 would appear in gray tones while the differences
therebetween would appear in color (either in a shade of red or a
shade of cyan). The intensity of the color difference would depend
upon the magnitude of the difference between the same portions of
the two recorded X-ray images. By switching the movable contact MB
of the switch SB to the fixed contact 52B the image recorded on the
track 52 could be compared with the reference image on the track
40. The same type of output would be produced with the common
portions being reproduced in gray tones and a difference being
reproduced in color. By moving the movable contact MB of the switch
SB to the fixed contact 58B the comparison between the images
recorded on the tracks 58 and 40 could be reproduced. By moving the
movable contact MA to any of the other of the fixed contacts
thereof a comparison of the various images recorded on the
recording tracks of the disc recorder 16 could be accomplished as
desired for the particular examination underway.
Also a comparison of any of the recorded tracks 40, 46, 52 and 58
can be made with the real time X-ray image presently being scanned
by the TV camera 14. This is accomplished by applying the output of
the TV camera 14 to a real time processor 70 which suitably
processes the video output of the camera 14 and delays it to
provide a proper comparison with the recorded video information.
The output of the processor 70 is applied to a fixed contact RA of
the switch SA and a fixed contact RB of the switch SB. Hence by
connecting movable arm MA to the contact RA the real time X-ray
image would be displayed as a red picture on the monitor 24.
Correspondingly if the movable arm MB is connected to the fixed
contact RB the real time video signals will be applied to the
green-blue input of the monitor 24. By the comparison of the real
time image with the recorded image, progressive changes in the
color output of the monitor 24 would be indicative of changes
occurring in real time as the X-ray image is being scanned. As
discussed above the common portions between the real time and
recorded images would be reproduced in gray tones.
In the system shown in FIG. 1 the saturation or vividness of the
color reproduced for the differences between the images is
controlled only by the difference in brightness between the red and
blue-green inputs being added. FIG. 2 shows an arrangement which
may be added to FIG. 1 which provides all the advantages of the
system of FIG. 1 but additionally provides for the separate
adjustment of the degree of saturation or vividness of the
difference color reproduced as desired by the user.
The arrangement shown in FIG. 2 is connected between the terminals
TA and TB of the switches SA and SB, respectively, and the R. G and
B inputs of the color monitor 24. The terminal TA supplying output
a is connected to the differencing input of an adder 100 and to one
summing input of each of three adders 102, 104 and 106. The b
output from the terminal TB is applied to the summing output of the
adder 100 so that the output thereof is b-a. This difference output
is applied to an amplifier 108 for amplification therein and is
applied to an amplitude control circuit 110, which for example may
comprise a potentiometer. The output of the amplitude control
circuit 110 may be varied so it provides an output x(b-a) where x
is a multiplication factor as determined by the amplifier 108 and
the setting of the amplitude control circuit 110. The output of the
amplitude control circuit 110 is applied to the other summing input
of the adder 102 to provide the output a + x(b-a) which is supplied
directly to the red input R of the color monitor 24. The output
x(b-a) of the amplitude control circuit 110 is also applied to a
phase inverter 112 wherein the polarity thereof is reversed to
provide the output -x(b-a). The output of the phase inverter 112 is
applied respectively to the other summing inputs of the adders 104
and 106, which each supply outputs a-x(b-a). The output of the
adder 104 is supplied directly to the green input G of the color
monitor 24 and the output of the adder 106 is directly applied to
the blue input B of the color monitor 24.
It can thus be seen that the input a from the switch SA appears at
each of the inputs R, G and B so that the picture produced by the
monitor 24 in response thereto will be a monochrome gray tone
picture. The difference signal b-a produced by the adder 100 is
controlled in amplitude by the amplitude control circuit 110 which
may be varied to control the saturation or vividness of the
difference signal. The difference signal modified by the factor x
is introduced into the red, green and blue inputs via the adders
102, 104 and 106 so that the modified difference signal x(b-a) will
be displayed on the color monitor 24 according to the magnitude of
the difference therebetween and the direction of this difference as
discussed above with reference to FIG. 1. However, in addition, the
saturation or vividness of color displayed may be controlled by the
factor x as desired by the user by setting the amplitude control
circuit 110.
* * * * *