BACKGROUND
1. Technical Field
[0002] The present invention relates to an image processing apparatus, an image processing
method, and a program for reading the front surfaces of media including portions printed with
I 0 ink which produces fluorescence during irradiation with ultraviolet rays.
2. Related Art
[0003] In financial institutions, if a check is received, the check is put on a check processing
apparatus, and magnetic ink characters printed on the check are magnetically read, whereby
15 magnetic information is acquired. Then, based on the magnetic information, a clearing
process is performed. Also, in financial institutions, in parallel with the reading of the
magnetic ink characters, the front surface of the check irradiated with visible rays is read by
the check processing apparatus, whereby an image of the front surface is acquired, and the
image is kept as an evidence of the clearing. Further, in financial institutions, in a case of
20 using a check on which there is a forgery prevention image printed with ink which produces
fluorescence during irradiation with ultraviolet rays (hereinafter, referred to as UV ink), the
front surface of the check irradiated with ultraviolet rays is read by a check processing
apparatus, whereby an image of the front surface is acquired, and the acquired image is used to
determine whether the check is genuine. Also, in financial institutions, the image of the front
25 surface of the check irradiated with the ultraviolet rays is kept as an evidence of clearing.
2
[0004] A check processing apparatus usable in that check clearing process is disclosed in JPA-
2013-070225. The check processing apparatus disclosed in JP-A-2013-070225 includes a
magnetic sensor for magnetically reading magnetic ink characters, and an image sensor for
irradiating the front surface of a check with read light, thereby acquiring an image ofthe front
5 surface. The image sensor emits visible rays and ultraviolet rays as read light. Also,
according to JIS Z 8120, the lower limit of the wavelengths of electromagnetic waves
.corresponding to visible rays is about 360 nm to 400 nm, and rays with wavelengths shorter
than those of visible rays are defined as ultraviolet rays.
[0005] The front surface of a check irradiated with ultraviolet rays is read by the image
10 sensor, whereby an image is acquired. This image is acquired by capturing light (ultraviolet
rays) reflected from the front surface of the check to the read light, and fluorescence produced
by UV ink forming a forgery prevention image. Also, the acquired image Is a gray scale
image in which image portions acquired by capturing the light (ultraviolet rays) reflected from
the front surface of the check to the read light are dark, and image portions acquired by
I 5 capturing the fluorescence produced by the UV ink are bright.
[0006] Here, in a case where the concentration of UV ink forming a forgery prevention
image is not sufficient, fluorescence weakens. As a result, image portions acquired by
capturing the fluorescence become dark, and thus it may become difficult to verify the forgery
prevention image based on an acquired image.
20 [0007] Also, in a case of keeping an image of the front surface of a check irradiated with
visible rays and an image of the front surface of the check irradiated with ultraviolet rays as
evidences of clearing based on the check, there is a problem in which the volume of data on
images to be kept increases. Here, in order to suppress the volume of data on images to be
kept as evidences of clearing, it can be considered to synthesize an image of the front surface
25 of a check irradiated with visible rays and an image of the front surface of the check irradiated
3
with ultraviolet rays into one image and keep the synthetic image.
[0008] However, in a case of simply synthesizing the two images of the front surface, some
problems such as a problem in which it becomes difficult to recognize a forgery prevention
image in the synthetic image occur.
5 [0009] An object of the present invention is to provide an image processing apparatus, an
image processing method, and a program for synthesizing an image of the front surface of a
medium irradiated with visible rays and an image ofthe front surface of the medium irradiated
with ultraviolet rays such that it is easy to discriminate a portion printed with UV ink, in view
ofthe above described points.
10
SUMMARY
[0010] (FIRST APPLICATION EXAMPLE)
(1) According to an aspect of the invention, an image processing apparatus includes
an image acquiring unit that reads the front surface of a medium irradiated with first light to
15 acquire a first image, and reads the front surface of the m~dium irradiated with second light
including ultraviolet rays to acquire a second image, by driving an image sensor, a first
corrected-image generating unit that generates a first corrected image by decreasing brightness
of the first image, a second corrected-image generating unit that generates a second corrected
image by increasing contrast of the second image, and a synthetic image generating unit that
20 generates a synthetic image by synthesizing the first corrected image and the second corrected
image.
[00 11] In the present invention, in a case of synthesizing the first image of the medium
irradiated with the first light such as visible light and the second image of the medium
irradiated with the second light including ultraviolet rays, the brightness (for example,
25 luminance) ofthe first image is decreased, whereby the first corrected image is generated, and
4
the contrast of the second image is increased, whereby the second corrected image is generated,
and then the first corrected image and the second corrected image are synthesized. Here, a
second image which can be acquired in a case of reading the front surface of a check irradiated
with ultraviolet rays is a gray scale image in which portions acquired by capturing light
5 reflected from the front surface of the check to the read light are dark (their luminance is low),
and a portion acquired by capturing fluorescence produced by a portion printed with UV ink is
bright (its luminance is high). Therefore, in a second corrected image acquired by increasing
the contrast of the second image, it is easier to discriminate the portion printed with UV ink as
compared to the second image. Also, by synthesizing the second corrected image with a first
10 corrected image acquired by decreasing the luminance of the first image, it is possible to
increase contrast between a portion of the second corrected image corresponding to the portion
printed with UV ink and the first corrected image. Therefore, it is possible to synthesize an
image of the front surface of a medium irradiated with visible rays and an image of the front
surface of the medium irradiated with ultraviolet rays such that it is easy to discriminate a
15 portion printed with UV ink.
20
[0012] (SECOND APPLICATION EXAMPLE)
(2) In the image processin9 apparatus of ( 1 ), the first corrected-image generating
unit generates the first corrected image by decreases luminance values of pixels of the first
image by a predetermined ratio.
According to this configuration, generation of the first corrected image is easy.
[00 13] (THIRD APPLICATION EXAMPLE)
(3) In the image processing apparatus of (1), the second corrected-image generating
unit includes an edge area extracting unit that extracts, as an edge area, an area including an
image portion in which a luminance value difference between neighboring pixels is larger than
25 a predetermined luminance difference, from the second image, a correction function
5
generating unit that classifies a plurality of pixels included in the edge area into a first pixel
group and a second pixel group having luminance values smaller than those of the first pixel
group, based on the luminance values, and generates a correction function to correct the
luminance values of the pixels such that contrast between pixels included in the first pixel
5 group and pixels included in the second pixel group increases, and a luminance-value
corrected image generating unit that generates the second corrected image by correcting the
luminance values of the pixels in the second image with the correction function.
According to this configuration, the edge area extracting unit extracts, as the edge
area, an image portion including the portion printed with UV ink and a portion of the front
10 surface of the medium unprinted with UV ink, from the image of the medium irradiated with
the ultraviolet rays. Then, the correction function generating unit generates the correction
function, such that contrast between a bright portion (the first pixel group) and a dark portion
(the second pixel group) in the edge area increases. Thereafter, the luminance-value
corrected image generating unit corrects the entire image based on the correction function,
15 thereby generating the second corrected image. As a result, in the second corrected image,
contrast between the portion printed with UV ink and the front surface of the medium
unprinted with UV ink increases. Therefore, it is easy to discriminate the portion printed
with UV ink.
20
[0014] (FOURTH APPLICATION EXAMPLE)
(4) In the image processing apparatus of (3), the edge area extracting unit extracts,
as the edge area, an area including an image portion in which a luminance value difference
between a first pixel and a second pixel neighboring each other is larger than the
predetermined luminance difference, and the larger of the luminance values of the first pixel
and the second pixel is larger than an average of the luminance values of the pixels in the
25 second image.
6·
In an image which is acquired by the image acquiring unit, the luminance values of
an image portion acquired by capturing fluorescence produced by UV ink are larger than the
average of the luminance values of all pixels in the image even in a case where the
concentration of the UV ink is not sufficient. Therefore, according to the above described
5 configuration, as the edge area, an image portion including a portion printed with UV ink can
be extracted.
[0015] (FIFTH APPLICATION EXAMPLE)
(5) In the image processing apparatus of (3), the correction function generating unit
classifies the plurality of pixels included in the edge area, into the first pixel group and the
10 second pixel group, based on a histogram of the luminance values of the plurality of pixels
included in the edge area.
In the present invention, in order to classify the plurality of pixels included in the
edge area into two pixel groups, the correction function generating unit can classify the
plurality of pixels included in the edge area, into the first pixel group and the second pixel
15 group, based on a histogram of the luminance values of the plurality of pixels included in the
edge area.
[0016] (SIXTH APPLICATION EXAMPLE)
(6) In the image processing apparatus of (5), the correction function generating unit
generates the correction function based on a first average luminance value which is an average
20 of the luminance values of the pixels included in the first pixel group, a second average
luminance value which is an average of the luminance values of the pixels included in the
second pixel group, and a third average luminance value which is an average of the first
average luminance value and the second average luminance value.
In the present invention, the correction function generating unit generates the
25 correction function, such that contrast between the pixels included in the first pixel group and
7
the pixels included in the second pixel group increases. To this end, the correction function
generating unit can generate the correction function based on the first average luminance value
which is the average ofthe luminance values of the pixels included in the first pixel group, the
second average luminance value which is the average of the luminance values of the pixels
5 included in the second pixel group, and the third average luminance value which is the average
ofthe first average luminance value and the second average luminance value.
[0017] (SEVENTH APPLICATION EXAMPLE)
(7) In the image processing apparatus of (3), the luminance values of synthetic
pixels of the synthetic image acquired by synthesizing pixels of the first corrected image and
10 pixels of the second corrected image are equal to or larger than the luminance values of the
pixels of the first corrected image and are equal to or larger than the luminance values of the
pixels ofthe second corrected image.
According to this configuration, since the luminance of pixels of the synthetic image
corresponding to the portion printed with UV ink does not decrease, it is easy to discriminate
15 that printed portion.
[00 18] (EIGHTH APPLICATION EXAMPLE)
(8) In the image processing apparatus of any one of (1) to (7), the first image includes an
image based on visible light, and the second image includes an image based on fluorescence
from UV ink.
20 According to this configuration, for example, it is possible to read the front surface of a
check having a forgery prevention image printed with UV ink, and synthesize an image of the
front surface of the check and the forgery prevention image, thereby generating a synthetic
image.
[00 19] (NINTH APPLICATION EXAMPLE)
25 (9) According to another aspect of the invention, an image processing method
8
includes reading a front surface of a medium irradiated with first light to acquire a first image,
and reading the front surface of the medium irradiated with second light including ultraviolet
rays to acquire a second image, by driving an image sensor,_ decreasing brightness of the first
image to generate a first corrected image, increasing contrast of the second image to generate a
5 second corrected image, and synthesizing the first corrected image and the second corrected
image to generate a synthetic image.
[0020] In the present invention, in a case of synthesizing the first image of the medium
irradiated with the first light such as visible light and the second image of the medium
irradiated with the second light including ultraviolet rays, the luminance of the first image is
I 0 decreased, whereby the first corrected image is generated, and the contrast of the second
image is increased, whereby the second corrected image is generated, and then the first
corrected image and the second corrected image are synthesized. Here, in the second
corrected image acquired by increasing the contrast of the second image, it is easier to
discriminate a portion printed with UV ink as compared to the second image. Also, by
15 synthesizing the second corrected image with the first corrected image acquired by decreasing
the luminance of the first image, it is possible to increase contrast between a portion of the
second corrected image corresponding to the portion printed with UV ink and the first
corrected image. Therefore, it is possible to synthesize an image of the front surface of a
medium irradiated with visible rays and an image of the front surface of the medium irradiated
20 with ultraviolet rays such that it is easy to discriminate a portion printed with UV ink.
[0021] (TENTH APPLICATION EXAMPLE)
25
(1 0) In the image processing method of (9), in the decreasing step, luminance
values of pixels of the first image are decreased by a predetermined ratio to generate the first
corrected image.
According to this configuration, generation of the first corrected image is easy.
9
[0022] (ELEVENTH APPLICATION EXAMPLE)
(11) In the image processing method of (9), from the second image, an area
including an image portion in which a luminance value difference between neighboring pixels
is larger than a predetermined luminance difference is extracted as an edge area, a plurality of
5 pixels included in the edge area is classified into a first pixel group and a second pixel group
.having luminance lower than that of the first pixel group, based on the luminance, and a
correction function is generated to correct the luminance values of the pixels such that contrast
between pixels included in the first pixel group and pixels included in the second pixel group
increases, and the second corrected image is generated by correcting the luminance values of
10 the pixels in the second image with the correction function.
In the present invention, in order to increase contrast between the portion printed with
UV ink and the front surface of the medium unprinted with UV ink, the following process is
possible. That is, from the second image, an area including an image portion in which a
luminance value difference between neighboring pixels is larger than a predetermined
15 luminance difference is extracted as the edge area. A plurality of pixels included in the edge
area is classified into a first pixel group and a second pixel group having luminance lower than
that of the first pixel group, based on the luminance, and a correction function is generated to
correct the luminance values of the pixels such that contrast between pixels included in the
first pixel group and pixels included in the second pixel group increases. The luminance
20 values of the pixels in the second image are corrected by the correction function, whereby the
second corrected image is generated.
[0023] (TWELFTH APPLICATION EXAMPLE)
(12) In the image processing method of (11 ), as the edge area, an area including an
image portion in which a luminance value difference between a first pixel and a second pixel
25 neighboring each other is larger than the luminance difference, and the larger of the luminance
10
values of the first pixel and the second pixel is larger than the average of the luminance values
ofthe pixels in the second image is extracted.
In the present invention, in order to extract, as the edge area, an image portion
including a portion printed with UV ink, it is preferable to extract, as the edge area, an area
5 including an image portion in which a luminance value difference between a first pixel and a
second pixel neighboring each other is larger than the luminance difference, and the larger of
the luminance values of the first pixel and the second pixel is larger than the average of the
luminance values ofthe pixels in the second image.
[0024] (THIRTEENTH APPLICATION EXAMPLE)
10 (13) In the image processing method of(11), the plurality ofpixels included in the
edge area is classified into the first pixel group and the second pixel group, based on a
histogram ofthe luminance values ofthe plurality of pixels included in the edge area.
In the present invention, in order to classify the plurality of pixels included in the
edge area into two pixel groups, it is possible to classify the plurality of pixels included in the
15 edge area into the first pixel group and the second pixel group, based on a histogram of the
luminance values of the plurality of pixels included in the edge area.
[0025] (FOURTEENTH APPLICATION EXAMPLE)
(14) In the image processing method of (13), the correction function is generated
based on a first average luminance value which is the average of the luminance values of the
20 pixels included in the first pixel group, a second average luminance value which is the average
of the luminance values of the pixels included in the second pixel group, and a third average
luminance value which is the average of the first average luminance value and the second
average luminance value.
In the present invention, in order to generate the correction function such that contrast
25 between the pixels included in the first pixel group and the pixels included in the second pixel
11
group increases, it is possible to generate the correction function based on the first average
luminance value which is the average of the luminance values of the pixels included in the
first pixel group, the second average luminance value which is the average of the luminance
values ofthe pixels included in the second pixel group, and the third average luminance value
5 which is the average of the first average luminance value and the second average luminance
value.
[0026] (FIFTEENTH APPLICATION EXAMPLE)
(15) In the image processing method of (11 ), the luminance values of synthetic
pixels of the synthetic image acquired by synthesizing pixels of the first corrected image and
10 pixels of the second corrected image are equal to or larger than the luminance values of the
pixels of the first corrected image and are equal to or larger than the luminance values of the
pixels of the second corrected image.
According to this configuration, since the luminance of pixels of the synthetic image
corresponding to the portion printed with UV ink does not decrease, it is easy to discriminate
15 that printed portion.
20
[0027] (SIXTEENTH APPLICATION EXAMPLE)
( 16) In the image processing method of any one of (9) to ( 15), the first image
includes an image based on visible light, and the second image includes an image based on
fluorescence from UV ink.
According to this configuration, for example, it is possible to read the front surface of
a check having a forgery prevention image printed with UV ink, and synthesize an image of
the front surface of the check and the forgery prevention image, thereby generating a synthetic
image.
[0028] (SEVENTEENTH APPLICATION EXAMPLE)
25 (17) According to another aspect of the invention, a program which is executed in a
12
control apparatus which controls an image sensor, makes the control apparatus function as an
image acquiring unit that reads the front surface of a medium irradiated with first light to
acquire a first image and reads the front surface of the medium irradiated with second light
including ultraviolet rays to acquire a second image, by driving the image sensor, a first
5 corrected-image generating unit that generates a first corrected image by decreasing luminance
of the first image, a second corrected-image generating unit that generates a second corrected
image by increasing contrast of the second image, and a synthetic image generating unit that
generates a synthetic image by synthesizing the first corrected image and the second corrected
image.
10 [0029] According to the present invention, in a case of synthesizing the first image of the
medium irradiated with the first light such as visible light and the second image of the medium
irradiated with the ultraviolet rays, the luminance of the first image is decreased, whereby the
first corrected image is generated, and the contrast of the second image is increased, whereby
the second corrected image is generated, and then the first corrected image and the second
15 . corrected image are synthesized. Here, in the second corrected image acquired by increasing
the contrast of the second image, it is easier to discriminate a portion printed with UV ink as
compared to the second image. Also, by synthesizing the second corrected image with the
first corrected image acquired by decreasing the luminance of the first image, it is possible to
increase contrast between a portion of the second corrected image corresponding to the portion
20 printed with the UV ink and the first corrected image. Therefore, it is possible to synthesize
an image of the front surface of a medium irradiated with visible rays and an image of the
front surface of the medium irradiated with ultraviolet rays such that it is easy to discriminate
a portion printed with UV ink.
[0030] (EIGHTEENTH APPLICATION EXAMPLE)
25 (18) In the program of (17), the program makes the second corrected-image
13
generating unit function as an edge area extracting unit that extracts, as an edge area, an area
including an image portion in which a luminance value difference between neighboring pixels
is larger than a predetermined luminance difference, from the second image, a correction
function generating unit that classifies a plurality of pixels included in the edge area into a first
5 pixel group and a second pixel group having luminance values smaller than those of the first
pixel group, based on the luminance values, and generates a correction function to correct the
luminance values of the pixels such that contrast between pixels included in the first pixel
group and pixels included in the second pixel group increases, and a luminance-value
corrected image generating unit that generates the second corrected image by correcting the
I 0 luminance values of the pixels in the second image with the correction function, thereby.
[0031] In the present invention, the edge area extracting unit extracts, as the edge area, an
image portion including the portion printed with UV ink and a portion of the front surface of
the medium unprinted with UV ink, from the second image of the medium irradiated with the
ultraviolet rays. Then, the correction function generating unit generates the correction
15 function, such that contrast between a bright portion (the first pixel group) and a dark portion
(the second pixel group) in the edge area increases. Thereafter, the luminance-value
corrected image generating unit corrects the entire image based on the correction function,
thereby generating the second corrected image. As a result, in the second corrected image,
contrast between the portion printed with UV ink and the front surface of the medium
20 unprinted with UV ink increases. Therefore, it is easy to discriminate the portion printed
with UV ink.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIGS. lA and lB are explanatory views of a check processing system and a check
25 according to the present invention, respectively.
14
FIG. 2 is a block diagram illustrating a control system of the check processing system.
FIGS. 3A to 30 are views for explaining a first front surface image and a first
corrected image ofthe check.
FIGS. 4A to 40 are views for explaining a second front surface image and a second
5 corrected image ofthe check.
10
FIG. 5 is a luminance value graph of an image portion of a front surface image of the
check.
FIGS. 6A and 68 are a histogram of luminance values in an edge area and an
explanatory view of a correction function, respectively.
FIGS. 7 A and 7B are views for explaining a synthetic image.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0033] Hereinafter, with reference to drawings, a check processing apparatus will be
described as an embodiment of an image processing apparatus according to the present
15 invention.
[0034] CHECK PROCESSING SYSTEM
FIG. 1 A is an explanatory view of a check processing system, and FIG. 1 B is an
explanatory view of a check. A check processing system (an image processing system) 1 is
for performing some processes, such as a clearing process based on a check 2. As shown in
20 FIG. lA, the check processing system 1 includes a check processing apparatus 5, and a control
apparatus (an image processing apparatus) 7 which is connected to the check processing
apparatus 5 by a cable 6 or the like such that communication is possible. The control
apparatus 7 includes a main apparatus body 8, and an input unit 9 and a display 10 which are
connected to the main apparatus body 8. The main apparatus body 8 is a computer.
25 [0035] On the front surface 2a of a check 2 to be brought into financial institutions, magnetic
15
ink characters 11 representing the account number or the like of a customer is printed with
magnetic ink as shown in FIG. lB. Also, on the front surface 2a of the check 2, a forgery
prevention image 12 is printed with UV ink which produces fluorescence during irradiation
with ultraviolet rays.
5 [0036] As shown in FIG. 1 A, the check processing apparatus 5 includes a magnetic sensor 15,
an image sensor 16, and a conveyance path 17 which extends through a magnetic read position
"A" ofthe magnetic sensor 15 and an image read position "B" ofthe image sensor 16. Also,
the check processing apparatus 5 includes a conveying mechanism 18, which conveys the
check 2 along the conveyance path 17 such that the check passes the magnetic read position
1 o "A" and the image read position "B", if the check is inserted into the conveyance path 17.
The conveying mechanism 18 includes pairs of conveying rollers 19 which forwards the check
2 while holding the check 2 therebetween if the check 2 is inserted into the conveyance path
17, and a conveyance motor 20 (see FIG. 2) which drives the pairs of conveying rollers I 9.
[003 7] The magnetic sensor 15 is disposed such that its magnetic read surface 21 faces the
15 conveyance path 17. The magnetic sensor 15 reads the magnetic ink characters 11 from the
check 2 passing the magnetic read position "A".
[0038] The image sensor 16 is a contact image sensor (CIS) module. The image sensor 16
irradiates the check 2 passing the image read position "B" with light, and reads light reflected
from the check 2 or light produced by the check 2. The image sensor 16 is disposed such that
20 an irradiating unit 25 and a reading unit (an imaging element) 26 face the conveyance path 17.
[0039] The irradiating unit 25 is provided linearly in a vertical direction perpendicular to the
conveyance direction C of the check 2. The irradiating unit 25 includes, as light emitting
elements, a plurality of red light emitting elements 25R for irradiation with red read light, a
plurality of green light emitting elements 250 for irradiation with green read light, a plurality
25 of blue light emitting elements 25B for irradiation with blue read light, and a plurality of
16
ultraviolet light emitting elements 25UV for irradiation with ultraviolet read light which is
composed of ultraviolet rays. The plurality of light emitting elements 25R, 25G, 25B, or
25UV for irradiation with one kind ofread light is arranged linearly in a vertical direction.
[0040] The reading unit 26 is provided linearly in a vertical direction along the irradiating
5 unit 25. The reading unit 26 is composed of an imaging element such as a CMOS sensor.
The reading unit 26 (the imaging element) successively reads lines vertically extending on the
check 2 passing the image read position "B", one line by one line, whenever the check 2 is
irradiated with read light.
[0041] The check processing apparatus 5 conveys the check 2 along the conveyance path 17
10 by the conveying mechanism 18. Then, the check processing apparatus 5 reads the magnetic
ink characters 11 from the check 2 passing the magnetic read position "A" by the magnetic
sensor 15, thereby acquiring magnetic information. Then, the check processing apparatus 5
transmits the read magnetic information to the control apparatus 7. Further, the check
processing apparatus 5 reads the front surface 2a of the check 2 from the check 2 passing the
15 image read position "B" by the image sensor 16, thereby acquiring read information, and
successively transmits the read information to the control apparatus 7.
[0042] The control apparatus 7 receives the magnetic information having been acquired by
the check processing apparatus 5, and performs a clearing process based on the magnetic
information and information input from the input unit 9.
20 [0043] Also, the control apparatus 7 acquires a first front surface image (a first image) and a
second front surface image (a second image) based on the read information successively
received from the check processing apparatus 5 (outputs from the image sensor 16). The first
front surface image is a gray scale (composite gray) image acquired by irradiating the check 2
with read light composed of visible rays (red read light, blue read light, and green read light),
25 and the second front surface image is an image acquired by irradiating the check 2 with read
17
light composed of ultraviolet rays. The first front surface image and the second front surface
image are composed of pixels according to the resolution of the image sensor 16.
[0044] Further, the control apparatus 7 corrects the first front surface image and the second
front surface image acquired, and then synthesizes the first front surface image and the second
5 front surface image, thereby generating a synthetic image. Then, the control apparatus 7
saves and keeps the synthetic image as an evidence ofthe clearing process.
[0045] CONTROL SYSTEM
FIG. 2 is a block diagram schematically illustrating a control system of the check
processing system 1. FIGS. 3A to 3D are views for explaining the first front surface image
10 and a first corrected image. FIGS. 4A to 4D are views for explaining the second front surface
image and a second corrected image.
[0046] As shown in FIG. 2, the control system of the check processing apparatus 5 mainly
consists of a control unit 31 including a CPU and so on. The control unit 31 is connected to a
communication unit 32 which includes a communication interface for performing
15 communication with the control apparatus 7. Also, the control unit 31 is connected to the
conveyance motor 20, the magnetic sensor 15, and the image sensor 16 through a driver (not
shown).
[0047] In the control unit 31, a control program is executed. The control program makes
the control unit 31 act as a conveyance control unit 33, a magnetic information acquiring unit
20 34, and an image reading unit 35. Therefore, the control unit 31 includes the conveyance
control unit 33, the magnetic information acquiring unit 34, and the image reading unit 35.
[0048] The conveyance control unit 33 drives the conveyance motor 20 such that the check 2
is conveyed along the conveyance path 17.
[0049] The magnetic information acquiring unit 34 drives the magnetic sensor 15, whereby
25 magnetic read information (a detection signal) is read from the magnetic ink characters 11 of
18
the check 2 passing the magnetic read position "A". Also, the magnetic information
acquiring unit 34 recognizes the magnetic ink characters 11 based on the magnetic read
information. Recognition of the magnetic ink characters 11 is performed by collating the
magnetic read information output from the magnetic sensor 15 with a signal waveform pattern
5 of the magnetic ink characters 11 saved and kept in advance. The magnetic information
acquiring unit 34 acquires the result of the recognition of the magnetic ink characters 11 as
magnetic information. If magnetic information is acquired, the magnetic information
acquiring unit 34 transmits that magnetic information to the control apparatus 7.
[0050] The image reading unit 35 drives the image sensor 16, whereby the front surface 2a
10 ofthe check 2 is read from the check 2 passing the image read position "B".
[0051] In order to read the front surface 2a of the check 2 by the image sensor 16, the image
reading unit 35 sequentially irradiates the front surface 2a of the check 2 with red read light,
green read light, blue read light, and ultraviolet read light, in this order, by the irradiating unit
25 while the check 2 is conveyed at the image read position "B" by an conveyance amount of
15 one line corresponding to a read resolution. Also, whenever the check 2 is conveyed by an
conveyance amount of one line, the image reading unit 35 controls the reading unit 26 such
that the image reading unit successively reads a front surface portion of the check 2
corresponding to one line and irradiated with red read light, a front surface portion of the
check 2 corresponding to one line and irradiated with blue read light, a front surface portion of
20 the check 2 corresponding to one line and irradiated with green read light, and a front surface
portion of the check 2 corresponding to one line and irradiated with ultraviolet read light.
Further, the image reading unit 35 successively transmits read information output from the ·
reading unit 26 during irradiation with red read light, read information output from the reading
unit 26 during iJTadiation with green read light, read information output from the reading unit
25 26 during irradiation with blue read light, and read information output from the reading unit 26
19
during irradiation with ultraviolet read light, to the control apparatus 7.
[0052] Also, as shown in FIG. 2, the control apparatus 7 includes a check processing
apparatus control unit 41, an image processing unit 42, and a clearing process unit 43. The
control apparatus 7 executes a program in the main apparatus body 8, thereby acting as the
5 check processing apparatus control unit 41, the image processing unit 42, and the clearing
process unit 43.
[0053] The check processing apparatus control unit 41 transmits a processing operation start
command for starting a check processing operation, to the check processing apparatus 5.
[0054] The image processing unit 42 acquires a first front surface image 01 (see FIG. 3A)
10 based on read information output from the reading unit 26 during irradiation with visible rays
(red read light, green read light, and blue read light). Also, the image reading unit 35
acquires a second front surface image 02 (see FIG. 4A) based on read infonnation output from
the reading unit 26 during irradiation with ultraviolet read light. Further, the image
processing unit 42 synthesizes the first front surface image 01 and the second front surface
15 image 02, thereby generating a synthetic image "I" (see FIG. 7 A).
[0055] The clearing process unit 43 performs a clearing process based on magnetic
information such as an account number received from the check processing apparatus 5, and
input information sucb as an amount of money input to the control apparatus 7 through the
input unit 9. Also, the clearing process unit 43 displays the synthetic image "I" generated by
20 the image processing unit 42, on the display 10. Further, the clearing process unit 43 saves
and keeps the synthetic image "I" in association with clearance information including
clearance date, the magnetic information, the input information, and so on.
[0056] Here, the image processing unit 42 includes an image acquiring unit 45, a correctedimage
generating unit 46, and a synthetic image generating unit 47.
25 [0057] The image acquiring unit 45 acquires the first front surface image 01 based on the
20
read information output from the reading unit 26 during irradiation with red read light, the
read information output from the reading unit 26 during irradiation with green read light, and
the read information output from the reading unit 26 during irradiation with blue read light.
FIG. 3A shows the first front surface image 01 which is acquired by the image acquiring unit
5 45. FIG. 3B is a brightness (luminance value) distribution histogram of the first front surface
image 01. Since the image is displayed on the display 10, brightness is represented by
luminance values, and the horizontal axis of the histogram represents luminance values, and
the vertical axis represents frequency (the number of pixels). Since the first front surface
image 01 is a gray scale image as described above, luminance values representing luminance
10 are represented by 256 gray levels, and a luminance value "0" is the darkest (black), and a
luminance value "255" is the brightest (white).
[0058] Also, the image acquiring unit 45 acquires the second front surface image 02 based
on the read information output from the reading unit 26 during irradiation with ultraviolet read
light. FIG. 4A shows the second front surface image 02 which is acquired by the image
15 acquiring unit 45. FIG. 4B is a brightness (luminance value) distribution histogram of the
second front surface image 02. In the second front surface image 02, a portion acquired by
capturing light (ultraviolet rays) reflected from the front surface of the check 2 to the read light
is dark (its luminance is low), and a portion acquired by capturing fluorescence produced by a
portion printed with UV ink is light (its luminance is high).
20 [0059] The corrected-image generating unit 46 includes a first corrected-image generating
unit 51 which corrects the first front surface image G 1, and a second corrected-image
generating unit 52 which corrects the second front surface image 02.
[0060] The first corrected-image generating unit 51 decreases the luminance value of each
pixel of the first front surface image G 1 at a predetermined ratio, thereby generating the first
25 corrected image. In the present embodiment, the first corrected-image generating unit 51
21
decreases the luminance value of each pixel of the first corrected-image generating unit 51 by
50%. FIG. 3C shows a first corrected image Hl which is generated by the first correctedimage
generating unit 51. FIG. 3D is a brightness (luminance ~alue) distribution histogram
ofthe first corrected image Hl. As shown in FIGS. 3A to 3D, the first corrected image Hl is
5 an image (with lower luminance) darker than the first front surface image 01.
[0061] The second corrected-image generating unit 52 includes an edge area extracting unit
53, a correction function generating unit 54, a luminance-value corrected image generating
unit 55.
[0062] If the second front surface image 02 is acquired, the edge area extracting unit 53
10 extracts an image portion of the second front surface image 02 as an edge area 56 (to be
described below). The edge area 56 is extracted with reference to the luminance values of
individual pixels in the second front surface image 02. The edge area 56 is an area including
an image portion in which a luminance value difference between a first pixel and a second
pixel neighboring each other is larger than a predetermined luminance difference. Also, the
15 edge area 56 is an area including an image portion in which the luminance value of a first
pixel is larger than the luminance value of a second pixel, and is larger than the average Ave of
the luminance values of all pixels ofthe second front surface image 02.
[0063] FIG. 5 is a graph illustrating the luminance of a portion of the second front surface
image 02 corresponding to a pixel line of the forgery prevention image 12 arranged in the
20 longitudinal direction of the check 2 (a direction corresponding to the conveyance direction C).
The horizontal axis represents the positions of pixels, and the vertical axis represents the
luminance values (0 to 255) of the pixels being at those positions. A luminance value "0"
represents black, and a luminance value "255" represents white. In the example shown in
FIG. 5, as image portions in which a luminance value difference between a first pixel and a
25 second pixel neighboring each other is larger than the predetermined luminance difference,
22
four image portions PI, P2, P3, and P4 exist. The image portion PI or P2 is an image portion
in which the luminance value of a first pixel with higher luminance is smaller than the average
Ave of the luminance values of all pixels in the image. The image portion P3 or P4 is an
image portion in which the luminance value of a first pixel with higher luminance is larger
5 than the average Ave of the luminance values of all pixels in the image.
[0064] Here, luminance values in an image portion acquired by capturing fluorescence
produced by UV ink are larger than the average Ave of the luminance values of all pixels in
the image even in a case where the concentration of UV ink is not sufficient. Therefore, the
image portions P3 and P4 including pixels having luminance values larger than the luminance
10 value average Ave are image portions acquired by imaging portions printed with UV ink.
Therefore, the edge area extracting unit 53 extracts the image portion P3 or image portion P4
as the edge area 56. The extracted edge area 56 is, for example, an area shown in FIG. 4A.
Also, the image portions PI and P2 correspond to front surface portions ofthe check 2 having
patterns or printed with general ink.
15 [0065] The correction function generating unit 54 classifies a plurality of pixels included in
the edge area 56 into a first pixel group and a second pixel group, based on their luminance
values. FIG. 6A is an example of a brightness (luminance value) distribution histogram of the
plurality of pixels included in the edge area 56. FIG. 6B is a correction function graph.
[0066] The histogram representing the brightness (luminance value) distribution of the
20 plurality of pixels included in the edge area 56 shows double-humped distribution with two
humps at a high luminance portion and a low luminance portion as shown in FIG. 6A.
Therefore, the correction function generating unit 54 uses an algorithm for finding a threshold
value to divide a plurality of values having double-humped distribution into two portions, to
classify the plurality of pixels of the edge area into the first pixel group and a second pixel
25 group having luminance values smaller than those in the first pixel group. As the algorithm
23
for finding a threshold value to divide a plurality of values having double-humped distribution,
Otsu's method and the like are known.
[0067] Also, the correction function generating unit 54 generates a correction function to
correct the luminance value of each pixel such that contrast between pixels included in the first
5 pixel group and pixels included in the second pixel group increases. The correction function
generating unit 54 generates the correction function based on a first average luminance value
Ll which is the average of the luminance values of the pixels included in the first pixel group,
a second average luminance value 12 which is the average of the luminance values of the
pixels included in the second pixel group, and a third average luminance value 13 which is the
10 average of the first average luminance value Ll and the second average luminance value 12.
[0068] Here, the generated configuration is for correcting the luminance values of pixels
having the first average luminance value 11 to a first target luminance value Tl, and
correcting the luminance values of pixels having the second average luminance value 12 to a
second target luminance value T2, and correcting the luminance values of pixels having the
15 third average luminance value 13 to a third target luminance value T3. The first target
luminance value Tl is larger than the second target luminance value T2 and the third target
luminance value T3, and is smaller than the maximum value (in the present embodiment,
"255") of the luminance values. The second target luminance value T2 is smaller than the
third target luminance value T3, and is larger than the minimum value (in the present
20 embodiment, "0") ofthe luminance values.
[0069] Also, the correction function is for correcting the luminance value of each pixel, such
that a first difference between the first target luminance value Tl and the first average
luminance value 11 becomes larger than a second difference between the second target
luminance value T2 and the second average luminance value 12 and a third difference
25 between the third target luminance value T3 and the third average luminance value 13, and the
24
second difference becomes smaller than the third difference. In the present embodiment, the
first average luminance value L 1 is 54.02, and the first target luminance value T1 is 200. The
first difference is 145.98. The second average luminance value L2 is 41.64, and the second
target luminance value T2 is 63. The second difference is 21.36. The third average
5 luminance value L3 is 47.83, and the third target luminance value T3 is 127. The second
difference is 97.17.
[0070] FIG. 6B shows an example of the correction function which is generated by the
correction function generating unit 54. In FIG. 6B, the horizontal axis represents the
luminance values (input luminance values) of the pixels before correction, and the vertical axis
10 represents the luminance values (corrected luminance values) of the pixels after correction.
In the present embodiment, the correction function is represented by a Bezier curve, a sigmoid
curve, or the like.
[0071] Also, the reason why the first target luminance value Tl is set to be smaller than the
maximum value (in the present embodiment, "255") of the luminance values is for preventing
15 or suppressing the luminance ofthe second corrected image acquiring by correcting the second
front surface image G2 by the correction function from being saturated at the maximum value.
Here, the second target luminance value T2 can be set to a value lower than the second
average luminance value L2, and be used to generate the correction function.
[0072] The luminance-value corrected image generating unit 55 corrects the luminance value
20 of each of every pixel in the second front surface image G2 by the correction function, thereby
generating a second corrected image H2. FIG. 4C shows the second corrected image H2.
FIG. 4D is a brightness (luminance value) distribution histogram of the second corrected
image H2. The second corrected image H2 shown in FIG. 4C has contrast higher than that of
the second front surface image G2 shown in FIG. 4A.
25 [0073] The synthetic image generating unit 47 synthesizes the first corrected image Hl and
25
the second corrected image H2, thereby generating a synthetic image"I". FIG. 7A is a view
for explaining the synthetic image "I" which is generated by the synthetic image generating
unit 47, and FIG. 7b is a brightness (luminance value) distribution histogram of the synthetic
image "I".
5 [0074] The synthetic image generating unit 47 synthesizes mutually corresponding pixels of
the first corrected image H1 and the second corrected image H2. The synthetic image
generating unit 4 7 synthesizes the first corrected image H 1 and the second corrected image H2,
such that in the synthetic image "I", the synthetic pixels of the pixels of the first corrected
image H1 and the pixels ofthe second corrected image H2 have luminance values equal to or
I 0 larger than the luminance values of the pixels of the first corrected image H1 and equal to or
larger than the luminance values of the pixels of the second corrected image H2.
[0075] In the present embodiment, the pixels of the first corrected image HI and the pixels
of the second corrected image H2 are synthesized based on the folJowing Expression 1. In
Expression 1, "Im" represents the luminance of a synthetic pixel, and "I1" represents a pixel of
15 the first corrected image HI, and "12" represents a pixel ofthe second corrected image H2.
Im = 255 x (1- (1 - I1/255) x (1 - 12/255)) ... (1)
[0076] The synthesizing method based on Expression 1 is to perform positive-negative
reversal on the first corrected image HI while performing positive-negative reversal on the
second corrected image H2, and overlap the pixels of the reversed first corrected image Hl
20 and the pixels of the reversed second corrected image H2, and perform positive-negative
reversal on the overlapped images, thereby generating the synthetic image "I".
[0077] FIG. 7 A shows the synthetic image "I" generated by the synthetic image generating
unit 47. The synthetic image "I" is an image acquired by synthesizing the first corrected
image HI acquired by decreasing the luminance of the first front surface image GI and the
25 second corrected image H2 acquired by increasing the contrast of the second front surface
26
image G2. Also, according to the synthesizing method which is used in the synthetic image
generating unit 47, in the synthetic image "I", the luminance of the synthetic pixels of the
pixels of the first corrected image H1 af1d the pixels of the second corrected image H2 does
not decrease. As a result, in the synthetic image "I", the luminance of pixels corresponding
5 to the forgery prevention image 12 does. not decrease. Therefore, it is easy to discriminate
the forgery prevention image 12.
10
[0078] Also, the synthetic image generating unit 47 may synthesize the pixels of the first
corrected image H1 and the pixels of the second corrected image H2 based on the following
Expression 2.
Im = max (ll, I2) ". (2)
[0079] The synthesizing method based on Expression 2 is to synthesize mutually
corresponding pixels of the first corrected image H 1 and the second corrected image H2 such
that the luminance value of each synthetic pixel is set to the larger of the luminance values of
two corresponding pixels, thereby generating the synthetic image "I".
15 [0080] CHECK PROCESSING OPERATION
In a financial institution, if the check 2 is received, in order to perform a clearing
process, the check 2 is inserted into the conveyance path 17 of the check processing apparatus
5, and a processing operation start command is transmitted from the control apparatus 7 to the
check processing apparatus 5.
20 [0081] As a result, the check processing apparatus 5 conveys the check 2 along the
conveyance path 17 while reading the magnetic ink characters 11 printed on the check 2 by the
magnetic sensor 15, thereby acquiring magnetic information. Also, the check processing
apparatus 5 transmits the acquired magnetic information to the control apparatus 7. Further,
the check processing apparatus 5 reads the front surface 2a of the check 2 by the image sensor
25 16, and successively transmits the read information,
27
[0082] If receiving the read information from the check processing apparatus 5, the control
apparatus 7 acquires the first front surface image 01 (FIG. 3A) and the second front surface
image 02 (FIG. 4A). Then, the control apparatus 7 corrects the luminance values of the first
front surface image 01, thereby generating the first corrected image HI (FIG. 3C). Also, the
5 control apparatus 7 generates the correction function based on the second front surface image
02, and corrects the second front surface image 02 by the correction function, thereby
generating the second corrected image H2 (FIG. 4C). Thereafter, the control apparatus 7
synthesizes the first corrected image HI and the second corrected image H2, thereby
generating the synthetic image "I" (FIG. 7 A), and displays the synthetic image "I" on the
1 o display 1 0.
[0083] Here, an operator checks whether the check 2 is genuine, based on the synthetic
image "I" displayed on the display 10. That is, the operator verifies checks the forgery
prevention image 12 shown in the synthetic image "I", on the display 10. Also, the operator
checks information on the front surface or the like based on the synthetic image "I" and the
15 check 2, and inputs information necessary for clearing to the main apparatus body 8 through
the input unit 9. If information necessary for clearing is input, a clearing process is
performed based on the input information and the magnetic information. If clearing is
completed, the control apparatus 7 saves and keeps the synthetic image "I" in association with
clearance information including clearance date, the magnetic information, the input
20 information, and the like.
[0084] According to the present embodiment, as evidences of clearing based on the check 2,
the first front surface image 01 of the check 2 irradiated with visible rays and the second front
surface image 02 of the check 2 irradiated with ultraviolet rays are not individually kept, but
the synthetic image "I" of the first front surface image 01 and the second front surface image
25 02 is kept. Therefore, it is possible to suppress the volume of data on images to be kept as
28
evidences of clearing.
[0085] Also, in the present embodiment, since the luminance of pixels in the synthetic image
"I" corresponding to the portion printed with UV ink is not lower than that in the second
corrected image H2 before synthesization, it is easy to discriminate the forgery prevention
5 image 12 in the synthetic image "1".
[0086] Further, in the present embodiment, in order to generate the first corrected image HI,
the luminance value of each pixel of the first front surface image G 1 is decreased at a constant
ratio. Therefore, generation of the first corrected image Hl is easy. Also, in the present
embodiment, the luminance value of each pixel of the first front surface image G 1 is decreased
10 at a constant ratio, whereby the brightness (luminance value) distribution histogram is
compressed, and the upper limit value of the luminance of the first corrected image HI is
decreased as shown in FIG. 30. Therefore, in the brightness (luminance value) distribution
histogram of the synthetic image "I", portions exceeding the upper limit value of the
luminance of the first corrected image HI can be determined as portions which do not
15 including information relative to the first corrected image H 1. That is, in the present
embodiment, since the luminance value of each pixel of the first front surface image G 1 is
uniformly decreased by 50%, and then the first front surface image G 1 and the second
corrected image H2 are synthesized, pixels with luminance values equal to or larger than 128
in the synthetic image "I" can be information added to the first corrected image HI due to
20 synthesization ofthe first corrected image HI and the second corrected image H2, and can be
determined as portions which do not include information on the first corrected image HI.
[0087] FIRST MODIFICATION
Also, the control apparatus 7 may display the first front surface image G 1 and the
second corrected image H2 on the display 10. In this case, the operator can check whether
25 the check 2 is genuine, based on the second corrected image H2 displayed on the display 10.
29
That is, the following process is possible. First, the operator verifies the forgery prevention
image I2 shown in the second corrected image H2, on the display I 0. The operator checks
information on the front surface or the like based on the first front surface image G I and the
check 2, and inputs information necessary for clearing, such as an amount of money and date,
5 to the main apparatus body 8 through the input unit 9. If information necessary for clearing
is input, the control apparatus 7 performs a clearing process based on the input information
and the magnetic information.
[0088] SECOND MODIFICATION
In the above described embodiment, as the image processing apparatus, the check
10 processing apparatus for processing checks has been exemplified. However, the present
invention can also be applied to image processing apparatuses for processing images read from
media printed with UV ink, other than checks. Also, in the above described embodiment, the
first corrected image HI and the second corrected image H2 are synthesized in an RGB color
space. However, the values ofthe pixels ofthe first corrected image HI and the values ofthe
15 pixels of the second corrected image H2 may be converted into values in an HSB color space,
and a synthetic image of the first corrected image HI and the second corrected image H2 may
be generated in the HSB color space.
[0089] THIRD MODIFICATION
Also, in the check processing system I, the image acquiring unit 45, the corrected-
20 image generating unit 46, and the synthetic image generating unit 47 may be included in the
check processing apparatus 5, not in the control apparatus 7. In this case, the synthetic image
generating unit 47 included in the check processing apparatus 5 transmits the synthetic image
"I" to the control apparatus 7. Also, in this case, the image processing program is executed
on the control unit (a controller) 31 of the check processing apparatus 5, thereby making the
25 control unit 31 act as the image acquiring unit 45, the corrected-image generating unit 46, and
30
the synthetic image generating unit 47.
[0090] OTHER MODIFICATIONS
Also, the check processing apparatus 5 may include a pair of image sensors I 6 which
is provided at the image read position "B" so as to face each other with the conveyance path
5 I 7 interposed therebetween, and acquire images of the front and rear surfaces of the check 2.
Also, the check processing apparatus 5 can acquire a color front surface image as the first front
surface image Gl. Further, the check processing apparatus 5 may include an image
recognizing unit which performs image recognition on the characters and the like on the front
surface 2a of the check 2, based on the first front surface image G 1. Furthermore, in the
1 0 check processing system I, the magnetic information acquiring unit 34 and the image
acquiring unit 45 may be included in the control apparatus 7, not in the check processing
apparatus 5. In this case, magnetic read information which is output from the magnetic
sensor I 5, and read information which is output from the reading unit 26 are transmitted from
the check processing apparatus 5 to the control apparatus 7.

WE CLAIM:
I. An image processing apparatus comprising:
an image acquiring unit that reads the front surface of a medium irradiated with first
5 light to acquire a first image, and reads the front surface of the medium irradiated with second
light including ultraviolet rays to acquire a second image, by driving an image sensor;
a first corrected-image generating unit that generates a first corrected image by
decreasing brightness ofthe first image;
a second corrected-image generating unit that generates a second corrected image by
10 increasing contrast of the second image; and
15
20
25
a synthetic image generating unit that generates a synthetic image by synthesizing the
first corrected image and the second corrected image.
2. The image processing apparatus according to claim I, wherein
the first corrected-image generating unit generates the first corrected image by
decreases luminance values of pixels ofthe first image by a predetermined ratio.
3. The image processing apparatus according to claim 1, wherein
the second corrected-image generating unit includes:
an edge area extracting unit that extracts, as an edge area, an area including
an image portion in which a luminance value difference between neighboring pixels
is larger than a predetermined luminance difference, from the second image;
a correction function generating unit that classifies a plurality of pixels
included in the edge area into a first pixel group and a second pixel group having
luminance values smaller than those of the first pixel group, based on the luminance
32
5
values, and generates a correction function to correct the luminance values of the
pixels such that contrast between pixels included in the first pixel group and pixels
included in the second pixel group increases; and
a luminance-value corrected image generating unit that generates the second
corrected image by correcting the luminance values of the pixels in the second image
with the correction function.
4. The image processing apparatus according to claim 3, wherein
the edge area extracting unit extracts, as the edge area, an area including an image
10 portion in which a luminance value difference between a first pixel and a second pixel
neighboring each other is larger than the predetermined luminance difference, and the larger of
the luminance values of the first pixel and the second pixel is larger than an average of the
luminance values of the pixels in the second image.
15
20
5. The image processing apparatus according to claim 3, wherein
the correction function generating unit classifies the plurality of pixels included in the
edge area, into the first pixel group and the second pixel group, based on a histogram of the
luminance values ofthe plurality of pixels included in the edge area.
6. The image processing apparatus according to claim 5, wherein
the correction function generating unit generates the correction function based on a
first average luminance value which is an average of the luminance values of the pixels
included in the first pixel group, a second average luminance value which is an average of the
luminance values of the pixels included in the second pixel group, and a third average
25 luminance value which is an average of the first average luminance value and the second
33
average luminance value.
7. The image processing apparatus according to claim 3, wherein
the luminance values of synthetic pixels of the synthetic image acquired by
5 synthesizing pixels of the first corrected image and pixels of the second corrected image are
equal to or larger than the luminance values of the pixels of the first corrected image and are
equal to or larger than the luminance values of the pixels of the second corrected image.
10
8. The image processing apparatus according to any one of claims 1 to 7, wherein
the first image includes an image based on visible light, and the second image
includes an image based on fluorescence from UV ink.
9. An image processing method comprising:
reading a front surface of a medium irradiated with first light to acquire a first image,
15 and reading the front surface of the medium irradiated with second light including ultraviolet
rays to acquire a second image, by driving an image sensor;
decreasing brightness of the first image to generate a first corrected image;
increasing contrast of the second image to generate a second corrected image; and
synthesizing the first corrected image and the second corrected image to generate a
20 synthetic image.
25
10. The image processing method according to claim 9, wherein
in the decreasing step, luminance values of pixels of the first image are decreased by
a predetermined ratio to generate the first corrected image.
34
5
10
11. The image processing method according to claim 9, wherein
from the second image, an area including an image portion in which a luminance
value difference between neighboring pixels is larger than a predetermined luminance
difference is extracted as an edge area,
a plurality of pixels included in the edge area is classified into a first pixel group and
a second pixel group having luminance lower than that of the first pixel group, based on the
luminance, and a correction function is generated to correct the luminance values of the pixels
such that contrast between pixels included in the first pixel group and pixels included in the
second pixel group increases, and
the second corrected image is generated by correcting the luminance values of the
pixels in the second image with the correction function.
12. The image processing method according to claim 11, wherein
as the edge area, an area including an image portion in which a luminance value
15 difference between a first pixel and a second pixel neighboring each other is larger than the
luminance difference, and the larger of the luminance values of the first pixel and the second
pixel is larger than the average of the luminance values of the pixels in the second image is
extracted.
20
25
13. The image processing method according to claim 11, wherein
the plurality of pixels included in the edge area is classified into the first pixel group
and the second pixel group, based on a histogram of the luminance values of the plurality of
pixels included in the edge area.
14. The image processing method according to claim 13, wherein
35
the correction function is generated based on a first average luminance value which is
the average of the luminance values of the pixels included in the first pixel group, a second
average luminance value which is the average of the luminance values of the pixels included
, '
in the second pixel group, and a third average luminance value which is the average ofthe first
5 average luminance value and the second average luminance value.
15. The image processing method according to claim 11, wherein
the luminance values of synthetic pixels of the synthetic image acquired by
synthesizing pixels of the first corrected image and pixels of the second corrected image are
10 equal to or larger than the luminance values of the pixels of the first corrected image and are
equal to or larger than the luminance values ofthe pixels of the second corrected image.
16. The image processing method according to any one of claims 9 to 15, wherein
the first image includes an image ba~ed on visible light, and the second image
15 includes an image based on fluorescence from UV ink.