1. Technical Field
[OOOl]
BACKGROUND
The present invention. relates to an image processing device that
drives an image sensor to acquire an image of a medium when exposed
to visible light and an image of the medium exposed to ultraviolet
light, and to an image processing method and a program.
2. Related Art
[0002J
When a check is presented to a financial institution, the check
is read by a check processing device, magnetic ink characters. printed
on the check are magnetically read, and payment is processed based
on the acquired magnetic information. Parallel to reading the magnetic
ink characters, the check processing device also emits visible light
to the front of the check to capture an image of the check, and the
financial insti tu tion stores the acquired check image as proof of the
transaction. When a check bearing a security image printed with UV
ink that fluoresces when exposed to ul traviolet light to prevent forgery
is presented to a financial institution, the check proces sing device
reads the front of the check with UV light by exposing it to UV light,
and the acquired check image is used to determine the authenticity
of the check. The financial institution also saves the check image
captured using ultraviolet light as proof of the transaction.
[0003J
One example of a check processing device that can be used in such
check payment processes is described in JP-A-2013-70225. The check
processing device described in JP-A-2013-70225 has a magnetic sensor
for magnetically reading magnetic ink characters, and an image sensor
for exposing the surface of the check to light and optically imaging
3
the check. The image sensor images the check using both visible light
.and ultraviolet light.
[0005J
A problem with storing an image of the check exposed to visible
light and an image of the check exposed to ul traviolet light as proof
of payment by a check is that the amount of image data to be stored
increases. To reduce the amount of image data stored as proof of a
transaction, the image of the check when exposed to visible light and
the image of the check when exposed to ultraviolet light could
conceivably be combined to store a single synthesized image.
[0006J
However, in an image that is captured by the image sensor reading
the surface of the check when exposed to ul traviolet light, the portions
that capture the reflection of ultraviolet light reflected from the
surface of the check are dark, and the portions that image the
fluorescence of the portions printed with UV ink are light gray scale
images. Furthermore, because the area of the portion printed with UV
ink is small compared wi th the total area of the check, the check image
is dark overall. Therefore, when the image of the check exposed to
visible light and the image of the check exposed to ultraviolet light
are combined, contrast drops in the synthesized image and the security
image becomes hard to recognize.
SUMMARY
[0007J
An objective of the present invention is to provide an image
processing device and an image processing method that combine an image
of the medium when exposed to visible light and an image of the medium
when exposed to ultraviolet light so that the portion printed with
UV ink can be easily determined. A further obj ecti ve of the invention
is to provide a program for a control device that controls driving
the image processing device of the invention.
4
[0008]
To solve the foregoing problem, an image processing device
according to the invention includes an image acquisition unit that
drives an image sen~or, acq~ires a first image by reading a surface
of a medium exposed to a visible first light, and acquires a second
image by reading a surface of the medium exposed to an ultraviolet
second light; a reverse image generating uni t that generates a reversed
second image by reversing light and dark in the second image; and a
synthesizing unit that generates a synthesized image by combining the
first image and the reversed second image.
[0009]
To combine a first image of a medium exposed to a visible first
light wi th a second image of the medium when exposed to an ul traviolet
second light, the invention generates a reversed second image by
reversing light and dark in the second image, and combines this reversed
second image wi th the first image. The second image acquired by scanning
the surface of the medium exposed to the second light with an image
sensor becomes an image that is dark overall when the area occupied
by the parts printed wi th UV ink is small compared wi th the total surface
area of the medium. The reversed second image will therefore become
an image that is light overall if the reversed second image is generated
by reversing light and dark in the second image. A drop in luminance
andadropincontrastinthesjnthesizedimagecanthereforebeprevented
by combining the reversed second image wi th the first image. Furthermore,
because the image parts capturing fluorescence from parts printed wi th
UV ink in the second image are light, the parts printed with UV ink
become a low luminance black color in the reversed second image. The
parts printed with UV ink can therefore be easily discerned in the
synthesized image obtained by combining the reversed second image and
the first image. Note tha t the parts printed wi th UVink become a reverse
image with light and dark reversed in the synthesized image, but the
parts printed with UV ink can also be easily confirmed in the reverse
image.
[0010J
5
Preferably in the invention, the second image includes an image
part based on fluorescence from UV ink. Thus comprised, the surface
of a check having a security image printed with UV ink can be imaged,
and a synthesized image combining the image of the check wi th the reverse
image of the security image can be generated.
[OOllJ
An image processing method according to the invention comprises:
acquiring a first image by reading a surface of a medium exposed to
a visible first light, and acquiring a second image by reading a surface
of the medium exposed to an ul traviolet second light, by an image sensor;
generating a reversed second image by reversing light and dark in the
second image; and generating a synthesized image by combining the first
image and the reversed second image.
[0012J
To combine a first image of a medium exposed to a visible first
light with a second image of the medium when exposed to an ul traviolet
second light, the invention generates a reversed second image by
reversing light and dark in the second image, and combines the first
image wi th the reversed second image. The reversed second image becomes
an image that is light overall if the portion printed with UV ink is
small. A drop in luminance and a drop in contrast in the synthesized
image can therefore be prevented by combining the reversed second image
wi th the first image. Furthermore, because the parts printed with UV
ink become a low luminance black color in the reversed second image,
the parts printed with UV ink can be easily discerned in the synthesized
image. Note that the parts printed with UV ink become a reverse image
with light and dark reversed in the synthesized image, but the parts
pr inted wi th UV ink can also be easily confirmed in the reverse image.
[0013J
Preferably in the invention, the second image includes an image
6
part based on fluorescence from UV ink. Thus comprised, the surface
of a check having a security image printed with UV ink can be read,
and a synthesized image combining the image of the check wi th the reverse
image of the security image can be generated.
[0014J
Another aspect of the invention is a program that operates on
a control device that controls driving an image sensbr, the program
causing the control device to function as: an image acquisition unit
that drives the image sensor, acquires a first image by reading a surface
of a medium exposed to a visible first light, and acquires a second
image by reading a surface of the medium exposed to an ultraviolet
second light; a reverse image generatIng unit that generates a reversed
second image by reversing light and dark in the second image; and a
synthesized image generating unit that generates a synthesized image
by combining the first image and the reverse image.
[0015]
To combine a first image of a medium exposed to a visible first
light wi th a second image of the medium when exposed to an ul traviolet
second light, the invention generates a reversed second image by
reversing light and dark in the second image, and combines the first
image wi th the reversed second image. The reversed second image becomes
an image that is light overall if the portion printed wi th UV ink is
small: A drop in luminance and a drop in contrast in the synthesii~d
image can therefore be prevented by combining the reversed second image
with the first image. Furthermore, because the parts printed with UV
ink become a low luminance black color in the reversed second image,
the parts printed wi th UV ink can be easily discerned in the synthesized
image. Note that the parts printed wi th UV ink become a reverse image
wi th light and dark reversed in the synthesized image, but the parts
printed wi th UV ink can also be easily confirmed in the reverse image.
BRIEF DESCRIPTION OF DRAWINGS
7
FIG. 1 illustrates a check processing system according to the
invention.
FIG. 2 is a block diagram of the control system of the check
processing system.
FIG. 3 shows an example of a dialog box presented on the display
of the control device.
FIG. 4 illustrates a first image and a second image captured from
a check.
FIG. 5 illustrates a first corrected image and a second corrected
image.
FIG. 6 is a graph of luminance values in the check image.
FIG. 7 shows a histogram of luminance values in edge areas and
describes a correction function.
FIG. 8 describes a first synthesized image.
FIG. 9 describes an inverted second image and a second synthesized
image.
DESCRIPTION OF EMBODIMENTS
[0017]
A preferred embodiment of a check processing system applying the
present invention is described below wi th reference to the accompanying
figures.
[0018]
Check processing system
FIG. 1 (a) illustrates a check processing system, and FIG. 1 (b)
shows an example of a check. The check processing system 1 executes
a payment process using a check 2. As shown in FIG. 1 (a), the check
processing system 1 includes a check processing device 5, and a control
device 7 communicatively connected to the check processing device 5
through a cable 6, for example. The control device (image processing
device) 7 includes a main unit 8, and an input device 9 and display
10 connected to the main unit 8. The main unit 8 is a computer.
8
[0019J
A line and the name of the financial institution, for example,
are printed in normal ink on the face 2a of the check 2 presented to
a financial institution as shown in FIG. 1 (b) . Magnetic ink characters
11 expressing the customer account number and other information are
also printed in magnetic ink on the face 2a of the check 2. A securi ty
image 12 that fluoresces when exposed to UV light is also printed on
the face 2a of the check 2 using UV ink.
[0020J
As shown in FIG. 1 (a) , the check processing device 5 has a magnetic
sensor 15, an image sensor 16,and a printhead 17. The check processing
device 5 also has a conveyance path 18 that passes the magnetic reading
position A of the magnetic sensor 15, the image reading position B
of the image sensor 16, and the printing position C of the printhead
17. The 5 also has a conveyance mechanism 19 that conveys a check 2
inserted to the conveyance path 18 past the magnetic reading position
A, image reading position B, and printing position C. The conveyance
mechanism 19 includes a conveyance roller pair 20 that holds and conveys
the check 2 inserted to the conveyance path 18, and a conveyance motor
21 (see FIG. 2) that drives the conveyance roller pair 20.
[0021J
The magnetic sensor 15 is disposed with the magnetic reading
surface 22 facing the conveyance path 18. The magnetic sensor 15 reads
the magnetic ink characters 11 from the check 2 passing the magnetic
reading position A.
[0022J
The image sensor 16 is a CIS (contact image sensor) module. The
image sensor 16 emits light to the check 2 passing the image reading
posi tion B and captures the reflection or fluorescence from the check
2. The image sensor 16 is disposed with the photoemitter unit 25 and
reading unit (imaging element) 26 facing the conveyance path 18.
[0023J
I
9
The photoemitter unit 25 is disposed on a vertical line
perpendicular to the conveyance direction D. The light elements of
the photoemitter unit 25 include a plurality of red photoemission
elements 25R that emit red light, a plurality of green photoemission
elements 25G that emit green light, a plurali ty of blue photoemission
elements 25B that emit blue light, and a plurality of UV photoemission
elements 25UV that emit ultraviolet light. The multiple photoemission
elements 25R, 25G, 25B, and 25UV that emit respective colors of light
are disposed in vertical lines.
[0024J
The reading unit 26 is displayed in a vertical line along the
photoemitter unit 25. The reading unit 26 is an imaging element such
as a CMOS sensor. The reading uni t 26 (imaging element) reads the check
2 passing the image reading position B sequentially one vertical line
at a time timed to emission of the reading beams to the check 2.
[0025J
The printhead 17 is disposed on the opposi te side of the conveyance
path 18 as the magnetic sensor 15 and image sensor 16. The printhead
17 is also disposed with the printing surface facing the conveyance
path 18. The printhead 17 prints an endorsement on the back 2b of the
check 2 passing the printing position C.
[0026 J
The check processing device 5 conveys checks 2 through the
conveyance path 18 by means of the conveyance mechanism 19. The check
processing device 5 reads the magnetic ink characters 11 from the check
2 passing the magnetic reading position A with the magnetic sensor
15 and acquires magnetic information. The check processing device 5
then sends the read magnetic information to the control device 7. The
check processing device 5 also reads the face 2a of the check 2 from
the check 2 passing the image reading position B by means of the image
sensor 16, and sequentially sends the scanning information to the
control device 7. The check processing device 5 also controls the
10
printhead 17 based on print commands from the control device 7, and
prints an endorsement on the check 2 used in the payment process.
[0027]
The control device 7 receives the magnetic information acquired
by the check processing device 5, and executes a payment process based
on the input information input from the input device 9.
[0028]
Based on the scanning information (output from the image sensor
16) sequentially sent from the check processing device 5, the control
device 7 acquires a first image G1 (first image, see FIG. 4 (a)) and
a second image G2 (second image, see FIG. 4 (b)). The first image G1
is a gray scale (composite gray) image captured when the check 2 is
exposed to visible light (red light, blue light, green light), and
the second image G2 is a gray scale image captured when the check 2
is exposed to ultraviolet light. The first image G1 and second image
G2 are composed of pixels corresponding to the resolution of the image
sensor 16.
[0029]
The control device 7 image processes at least one of the acquired
first image G1 and second image G2, and then generates a synthesized
image combining these images. The control device 7 stores the generated
synthesized image as proof of the payment process.
[0030]
The control device 7 can create two types of synthesized images,
a first synthesized image 11 (see FIG. 8 (a)) and a second synthesized
image 12 (see FIG. 9 (b)). The first synthesized image 11 is created
by generating a first corrected image that reduces the luminance of
the first image G1, and a second corrected image that increases the
contrast of the second image G2, and then combining the first corrected
image and second corrected image. The second synthesized image 12 is
created by generating a reversed second image by reversing light and
dark values in the second image G2, and then combining the first image
11
Gl and the reversed second image. The control device 7 generates one
of the synthesized images based on synthesized image selection
information previously input by the op~rator.
[0031J
When the payment process ends, the control device 7 sends a print
command to the checkprocessingdevice 5 and drives the check processing
device 5 to print an endorsement on the check 2.
[0032J
Control system of the check'processing device
FIG. 2 is a block diagram illustrating the control system of the
check processing system 1. FIG. 3 illustrates a dialog box for selecting
the synthesized image. FIG. 4 describes the first image Gl and second
image G2. FIG. 5 describes the first corrected image and second corrected
image.
[0033J
As shown in FIG. 2, the control system of the check processing
device 5 is configured around a control unit 31 comprising a cpu. A
communication unit 32 with a communication interface for communicating
with the control device 7 is connected to the control unit 31. The
magnetic sensor 15, image sensor 16, printhead 17, and conveyance motor
21 are also connected to the control unit 31 through drivers not shown.
[0034J
A control program operates on the control unit 31. The control
program causes the control unit 31 to function as a conveyance control
. unit 33, magnetic information acquisition unit 34, image scanning unit
35,andprintunit36.Thecontrolunit31thereforeincludesaconveyance
control unit 33, magnetic information acquisition unit 34, image
scanning unit 35 and print unit 36.
[0035J
The conveyance control unit 33 controls driving the conveyance
motor 21 to convey a check 2 through the conveyance path 18.
[0036J
12
The magnetic information acquisition unit 34 drives the magnetic
sensor 15 to acquire magnetic reading information (detection signal)
from the magnetic ink characters 11 of the check 2 passing the magnetic
reading position A. Based on the magnetic reading information, the
magnetic information acquisition unit 34 recognizes the magnetic ink
characters 11. Recognition of the magnetic ink characters 11 is done
by comparing the magnetic reading information output from the magnetic
sensor 15 with the previously stored signal waveform patterns of the
magnetic ink characters 11. The magnetic information acquisition unit
34 acquires the result of recognizing the magnetic ink characters 11
as magnetic information. When the magnetic information is acquired,
the magnetic information acquisition unit 34 outputs the magnetic
information to the control device 7.
[0037J
The image scanning unit 35 drives the image sensor 16 to read
the face 2a of the check 2 passing the image reading position B.
[0038J
When scanning the face 2a of the check 2 with the image sensor
16, the image scanning unit 35 sequentially emits red light, green
light, blue light, and ultraviolet light from the photoemitter unit
25 to the face 2a of the check 2 at the image reading posi tion B while
advancing the check 2 the distance of one line, which is determined
by the scanning resolution. Each time the check 2 is advanced the distance
of one line, the image scanning unit 35 controls the reading unit 26
to sequentially capture a one-line image of the check 2 when exposed
to red light, an image of one line of the check 2 when exposed to blue
light, an image of one line of the check 2 when exposed to green light,
and an image of one line of the check 2 when exposed to ultraviolet
light. The image scanning uni t 35 then sequentially sends the scanning
information output from the reading uni t 26 when red light is emi tted,
the scanning information output from the reading unit 26 when blue
light is emitted, the scanning information output from the reading
13
unit 26 when green light is emitted, and the scanning information output
from the reading uni t 26 when ul traviolet light is emi tted to the control
device 7.
[0039]
The print unit 36 drives the printhead 17 based on print commands
output from the control device 7 to print on the back 2b of the check
2 passing the printing position C.
[0040]
Control system of the control device
As shown in FIG. 2, the control device 7 has a check processing
device control uni t 40, a synthesized image selection uni t 41, an image
processing uni t 42, and a payment processing uni t 43. The control device
7 functions as the check processing device control unit 40, synthesized
image selection unit 41, image processing unit 42, and payment
processing unit 43 as a result of a program running on the main unit
8.
[0041]
The check processing device control unit 40 sends a start
processing command that starts the check scanning operation to the
check processing device 5. The check scanning operation is an operation
that conveys the check 2 through the conveyance path 18 and sends the
captured magnetic information and scanning information to the control
device 7.
[0042]
The synthesized image selection unit 41 displays a dialog box
44 on the display 10, and accepts input of synthesized image selection
information. FIG. 3 shows an example of the dialog box 44 the synthesi zed
image selection unit 41 presents on the display 10. The synthesized
image selection information specifies whether to use the first
synthesized image 11 or the second synthesized image 12 as the
synthesized image that is stored as proof of the payment process.
A pulldown menu 44a for selecting the first synthesized image
14
II or second synthesized image 12 is provided in the dialog box 44.
In this example, if the operator selects "Merge type 1" from the pulldown
menu 44a, synthesized image selection information specifying the first
synthesized image 11 as the synthesized image is input to the control
device 7. If the operator selects "Merge type 2" from the pulldown
menu44a, synthesizedimage selection information specifying the secon d
synthesized image 12 as the synthesized image is input to the control
device 7.
[0043]
The image processing unit 42 has an image acquisition unit 45
that acquires the first image G1 based on the scanning information
output from the reading unit 26 while visible light (red light, green
light, blue light) is emitted, and acquires the second image G2 based
on the scanning information output from the reading unit 26 while
ultraviolet light is emitted. The image processing unit 42 also has
a first synthesized image generating unit 46 that generates the first
synthesized image 11, and a second synthesized image generating unit
47 that generates the second synthesized image 12.
[0044]
The image acquisition unit 45 acquires the first image G1 based
on the scanning information output from the reading unit 26 while red
light is emitted, the scanning information output from the reading
unit 26 while blue light is emitted, and the scanning information output
from the reading unit 26 while green light is emitted. The first image
G1 acquired by the image acquisition unit 45 is the image shown on
top in FIG. 4 (a) . The figure on the bottom in FIG. 4 (a) is a histogram
of the distribution of brightness (luminance) in the first image G1.
Note that this image represents brightness by luminance values because
it is displayed on the display 10. Luminance values are on the X-axis
in the histogram, and the count (pixel count) is on the Y-axis. As
described above, the first image G1 is a gray scale image. There are
256 luminance values representing brightness with a luminance value
15
of 0 being the darkest (black) and a luminance value of 255 being the
brightest (white).
[0045]
The image acquisition unit 45 also acquires the second image G2
based on the scanning information output from the reading unit 26 while
ul traviolet light is emitted. A second image G2 acquired by the image
acquisition unit 45 is shown on the top in FIG. 4 (b). The figure on
the bottom in FIG. 4 (b) is a histogram of the distribution of brightness
(1 uminance) in the second image G2 . In the second image G2, areas imaging
the reflection (ultraviolet rays) of the scanning beam reflected from
the surface of the check 2 are dark (luminance is low), and areas imaging
the fluorescence produced by the portions printed wi th UV ink are light
(luminance is high).
[0046]
The first synthesized image generating unit 46 operates when
synthesized image selection information specifying the first
synthesized image II as the synthesized image is input to the control
device 7. The first synthesized image generating unit 46 has a first
corrected image generating unit 51 that corrects the first image Gl,
a second corrected image generating unit 52 that corrects the second'
image G2, and a first synthesizing unit 53 that combines the first
corrected image HI resulting from correcting the first image G1 and
the second corrected image H2 resulting from correcting the second
image G2.
[0047]
The first corrected image generating unit 51 generates the first
corrected image HI by reducing the luminance of each pixel in the first
image G1 a constant rate. In this example, the luminance of each pixel
in the first image G1 is reduced 50%. A first corrected image H1 generated
by the first corrected image generating unit 51 is shown on the top
in FIG. 5 (a). The figure on the bottom in FIG. 5 (a) is a histogram
of the distribution of brightness (luminance values) in the first
16
corrected image HI. The first corrected image HI is a darker image
(has lower luminance) than the first image Gl shown in FIG. 4.
[0048]
The second ~orrected image generating unit 52 has an edge
extraction unit 54, a correction function generating unit 55, and a
corrected luminance image generating unit 56.
[0049]
When a second image G2 is acquired, the edge extraction unit 54
extracts parts of the second image G2 as edge areas. An edge area is
extracted using the luminance value of each pixel in the second image
G2. An edge area is an area including a part of the image where the
difference of the luminance values of a first pixel and an adjacent
second pixel is greater than a preset luminance difference. An edge
area is also an area including a part of the image where the luminance
value of the first pixel, which has a higher luminance value than the
second pixel, is greater than the average luminance Ave of all pixels
in the second image G2.
[0050]
FIG. 6 is a graph of the luminance of part of a pixel train in
the second image G2 passing through the sec~rity image 12 in the
lengthwise direction of the check 2 (the direction corresponding to
the conveyance direction 0) . The pixel posi tions are shown on the X-axis,
and the luminance (0 - 255) of the pixel at that position is shown
on the Y-axis. A luminance value of 0 is black, and a luminance value
of 255 is white.
In the example shown in FIG. 6, there are four image parts, PI,
P2, P3, P4, where the luminance difference of a first pixel and the
adj acent second pixel is greater than a specific luminance difference.
In image parts PI and P2, the luminance of the high luminance first
pixel is lower than the average luminance Ave of all pixels in the
image. In image parts P3 and P4, the luminance of the high luminance
first pixel is higher than the average luminance Ave of all pixels
in the image.
[0051 J
17
The luminance of image parts capturing the fluorescence produced
by UV ink is higher than the average luminance Ave of all pixels in
the image even when the density of the UV ink is low. Image parts P3,
P4 including pixels with higher luminance than the average luminance
Ave are therefore images of parts printed wi th UV ink. The edge extraction
unit 54 therefore extracts image part P3 or image part P4 as an edge
area~ An extracted edge area 57 is an area such as shown in FIG. 4
(b) . Note that parts PI and P2 are parts where there is a pattern on
the face of the check 2 or where there is printing with normal ink.
[0052J
The correction function generating unit 55 separates the plural
pixels contained in the edge area 57 into a first pixel group and a
second pixel group based on the luminance values. FIG. 7 (a) is a
histogram of the distribution of brightness (luminance values) of the
plural pixels in the edge area 57. FIG. 7 (b) is a graph of a correction
function.
[0053J
As shown in FIG. 7 (a), the histogram of the distribution of the
brightness (luminance values) of the plural pixels in the edge area
57 have a bimodal distribution formed bya high luminance peak and
a low luminance peak. The correction function generating unit 55
therefore groups the plural pixels into a first pixel group and a second·
pixel group with lower luminance than the first pixel group using an
algori thm for finding a threshold value for separating the plural values
of the bimodal distribution into two groups. The discriminant analysis
method is one example of an algori thm for finding the threshold value
for dividing plural values wi ~h a bimodal distribution into two groups.
[0054J
The correction function generating uni t 55 generates a correction
function that corrects the luminance value of each pixel so that the
18
contrast between the pixels in the first pixel group and the pixels
in the second pixel group increases. The correction function generating
unit 55 generates the correction function based on a first average
luminance Ll that averages the luminance values of the pixels in the
first pixel group, a second average luminance L2 that averages the
luminance values of the pixels in the second pixel group, and a third
average luminance L3 that averages the first average luminance Ll and
the second average luminance L2.
[0055J
The generated correction function corrects the luminance values
of the pixels of the first average luminance Ll to a first target
luminance Tl, corrects the luminance values of the pixels of the second
average luminance L2 to a second target luminance T2, and corrects
the luminance values of the pixels of the third average luminance L3
to a third target luminance T3.
The first target luminance Tl is greater than the second target
luminance T2 and the third target luminance T3, and is lower than the
maximum luminance value (255 in this example).
The second target luminance T2 is lower than the third target
luminance T3, and is lower than the minimum luminance value (0 in this
example) .
[0056J
The correction function corrects the luminance value of each pixel
so that a first difference between the first target luminance Tl and
the first average luminance Ll is greater than a second difference
between the second target luminance T2 and the second average luminance
L2 and is greater than a third difference between the third target
luminance T3 and the third average luminance L3, and the second
difference is less than the third difference.
In this example,' the first average luminance 11 is 54.02, and
the first target luminance Tl is 200. The first difference is therefore
145.98. The second average luminance L2 is 41. 64, and the second target
19
luminance T2 is 63. The second difference is therefore 21.36. The third
average luminance L3 is 47.83, and the third target luminance T3 is
127. The third difference is 79.17.
[0057]
An example of the correction function generated by the correction
function generating unit 55 is shown in FIG. 7 (b) . The luminance values
(input luminance values) of the pixels before correction are shown
ontheX-axisinFIG.7 (b), andtheluminancevalues (correctedluminance
values) of the pixels after correction are shown on the Y-axis. The
correction function in this example may be represented by a Bezier
curve or a sigmoid curve, for example.
[0058]
The first target luminance Tl is lower than the maximum luminance
value (255 in this example) to prevent or suppress the luminance of
the second corrected image obtained by correcting the second image
G2 with the correction function from becoming saturated at the maximum
luminance. The correction function can also be generated wi th the second
target luminance T2 lower than the second average luminance L2.
[0059]
The corrected luminance image generating unit 56 generates a
second corrected image H2 in which the luminance value of each pixel
in the second image G2 is corrected with the correction function. An
example of the second corrected image H2 is shown on the top in FIG.
5 (b). The image on the bottom in FIG. 5 (b) is a histogram of the
distribution of brightness (luminance values) in the second corrected
image H2. The second corrected image H2 shown in FIG. 5 (b) is an image
with greater contrast than the second image G2 shown in FIG. 4 (b).
[0060]
The first synthesizing uni t 53 combines the first corrected image
HI and the second corrected image H2 to create the first synthesized
image II. FIG. 8 (a) shows an example of the synthesized image generated
by the first synthesizing unit 53, and FIG. 8 (b) is a histogram of
20
the distribution of brightness (luminance values) in the synthesized
image.
[0061]
The first synthesizing unit 53 combines corresponding pixels in
the first corrected image Hi and the second corrected image H2. The
first synthesizing unit 53 combines the first corrected image Hi and
second corrected image H2 so that the luminance of a synthesized pixel
combining a pixel in the first corrected image Hi and a pixel in the
second corrected image H2 is greater than or equal to the luminance
of that pixel in the first corrected image Hi and is greater than or
equal to the luminance of that pixel in the second corrected image
H2.
[0062]
In this example, the first synthesizing unit 53 combines pixels
in the first corrected image Hi and pixels in the second corrected
image H2 based on the following equation (1). In equation (1), 1m is
the luminance of the synthesized pixel, Ii is the luminance of the
pixel in the first corrected image Hi, and 12 is the luminance of the
pixel in the second corrected image H2.
1m = 255 x (1- (1-11/255) x (1-12/255)) (1)
[0063]
The synthesizing method based on equation (1) reverses negative
andposi ti ve values in the first corrected image Hi and reverses negative
and positive values in the second corrected image H2, superimposes
the pixels in the reversed first corrected image Hi with the pixels
in the reversed second corrected image H2, and then reverses nega ti ves
and positives in the combined image to create the first synthesized
image Ii.
[0064]
An example of the first synthesized image Ii produced by the first
synthesizing unit 53 is shown in FIG. 8 (a). The first synthesized
image Ii combines the first corrected image Hi in which the luminance
I
I
I I
21
of the first image Gl is reduced with the second corrected image H2
in which the contrast of the second image G2 is increased. The
synthesizing method of the first synthesizimg unit 53 does not reduce
the luminance of the synthesized pixels in the first synthesized image
II combining pixels in the first corrected image HI with pixels in
the second corrected image H2. As a result, because the luminance of
. pixels in the security image 12 does not drop in the first synthesized
image II, the security image 12 canbe easily identified. Content written
on the face 2a of the check 2 can also be easily read.
[0065]
Note that the first synthesizing uni t 53 may alternatively combine
pixels in the first corrected image HI and pixels in the second corrected
image H2 based on the following equation (2).
1m = max (II, 12) (2)
[0066]
When corresponding pixels in the first corrected image ~1 and
second corrected image H2 are combined by the synthesizing method based
on equation (2), the luminance value of the pixel with the higher
luminance value of the two pixels is used as the luminance value of
the synthesized pixel in the first synthesized image II.
[0067]
Next, the second synthesized image generating unit 47 operates
when the synthesized image selection information input to the control
device 7 specifies the second synthesized image 12 as the synthesized
image. As shown in FIG. 2, the second synthesized image generating
uni t 47 has a reverse image generating uni t 61 and a second synthesizing
unit 62. FIG. 9 (a) illustrates a reversed second image J2 geneyated
by the reverse image generating unit, and FIG. 9 (b) illustrates the
second synthesized image 12.
[0068]
The reverse image generating unit 61 generates a reversed second
image J2 as a positive-negative reversal of the second image G2 (by
22
reversing light and dark in the second image G2). A reversed second
image J2 generated by the reverse image generating unit 61 is shown
in FIG. 9 (a).
As shown on top in FIG. 4 (b), in the second image G2 acquired
based on the scanning information output from the reading unit 26 of
theimagesensor16whileultravioletlightisemitted,thepartsimaging
the reflection (ultraviolet light) of the scanning light reflected
by the surface of the check 2 are dark (luminance is low), and the
parts imaging the fluorescence produced by the parts printed with UV
ink are light (luminance is high) . In addition, because the area occupied
by the parts printed with UV ink is small compared wi th the total area
of the face 2a of the check 2, the second image G2 is a dark image
overall. As a result, the reversed second image J2 obtained as the
reverse of the second image is a bright image overall. Furthermore,
because the parts imaging the fluorescence from the parts printed wi th
UV ink in the second image G2 are bright, the security image 12 (the
parts printed with UV ink) becomes a low luminance black color in the
reversed second image J2.
[0069]
The second synthesizing unit 62 combines corresponding pixels
in the first image G1 and the reversed second image J2. The second
synthesizing uni t 62 combines the uncorrected first image G1 wi th the
overall bright reversed second image J2. A drop in luminance and a
drop in contrast in the second synthesized image 12 can therefore be
suppressed. The security image 12 also becomes a low luminance black
color in the second synthesized image 12. As a result, content written
on the face 2a of the check 2 can be easily read in the second synthesized
image 12, and the security image 12 can be easily identified. Note
.that while the security image 12 becomes a dark image with light and
dark reversed in the second synthesized image 12, the security image
12 can also be easily recognized in the reverse image.
[0070]
23
The image process whereby the second synthesized image generating
unit 47 combines pixels in the reversed second image J2 reversing
negative and positive in the second image G2 with the pixels in the
first image G1 to generate the second synthesized image 12 is shown
in equation (3) below. In equation (3), 1m is the luminance of the
synthesized pixel, 11 is the luminance of the pixel in the first image
Gl,and 12 is the luminance of the pixel in the second image G2.
1m = 255 x ( 11/255) x ( 1- I 2/255) ) (3)
[0071 J
The payment processing unit 43 executes the payment process based
on magnetic information including the account number received from
the check processing device 5, and input information such as the amount
input to the control device 7 through the input device 9. The payment
processing unit 43 also displays the first synthesized image 11 or
the second synthesized image 12 generated by the image processing uni t
42 on the display 10. The payment processing unit 43 also stores the
first synthesized image II or the second synthesized image 12
relationally to transaction information including the payment date,
the magnetic information, and the input information. The payment
processing unit 43 also stores and saves the first synthesized image
11 or second synthesized image 12, and sends a print command for printing
an endorsement to the check processing device 5.
[0072J
Check processing operation
In the payment process executed at the financial institution to
which the check 2 is presented, the check 2 is inserted to the conveyance
path 18 of the check processing device 5, and a start processing command
is sent from the control device 7 to the check processing device 5.
[0073J
As a result, the check processing device 5 conveys the check 2
through the conveyance path 18, reads the magnetic ink characters 11
printed on the check 2 with the magnetic sensor 15, and acquires the
24
magnetic information. The check processing device 5 also sends the
acquired magnetic information to the control device 7. The check
processing device 5 also scans the face 2a of the check 2 with the
image sensor 16, and sequentially sends the scanning information to
the control device 7.
[0074]
When the scanning information is received from the check
processing device 5, the control device 7 acquires the first image
G1 (FIG. 4 (a)) and the second image G2 (FIG. 4 (b)).
[0075]
When synthesized image selection information specifying using
the first synthesized image 11 as the synthesized image is input by
the operator to the control device 7, the control device 7 generates
the first corrected image H1 in which the luminance values of the first
image G1 are corrected (see FIG. 5 (a)). The control device 7 also
generates the correction function based on the second image G2, and
generates the second corrected image H2 by correcting he second image
G2 with the correction function (see FIG. 5 (b)). The control device
7 then generates the first synthesized image 11 by combining the first
corrected image H1 and second corrected image H2 (see FIG. 8 (a)),
and displays this first synthesized image 11 on the display 10.
[0076]
When the synthesized image selection information input to the
control device 7 by the operator specifies using the second synthesized
image 12 as the synthesized image, the control device 7 generates the
reversed second image J2 as a positive-negative reversal of the second
image G2 (FIG. 9 (a).) • The control device 7 also generates the second
synthesized image 12 combining the first image G1 and reversed second
image J2 (FIG. 9 (b)), and displays this second synthesized image 12
on the display 10.
[0077]
The operator then checks the authenticity of the check 2 based
25
on the synthesized image (the first synthesized image II or the second
synthesized image 12) shown on the display 10. More specifically, the
operator inspects the security image 12 that appears in the synthesized
image (first synthesized image II or second synthesized image 12) on
the display 10. The operator also checks the payment information based
on the synthesized image (first synthesized image II or second
synthesized image .12) and the check 2, and inputs the information
required to settle payment to the main uni t 8 through the input device
9.
[0078]
When the information required to settle payment is input, the
payment process is executed based on the input information and the
magnetic information. When payment is completed, the control device
7 relationally stores the synthesized image (first synthesized image
II or the second synthesized image 12) with transaction information
including the payment date, the magnetic information, and the input
information. The control device 7 also sends a print command to the
check processing device 5 and prints an endorsement on the check 2.
[0079]
Instead of separately storing a first image Gl of the check 2
when exposed to visible light and a second image G2 of the check 2
when exposed to ultraviolet light as proof of payment by the check
2, this example stores a synthesized image (first synthesized image
II or second synthesized image 12) combining these images. The amount
of image data stored as proof of payment can therefore be suppressed.
[0080]
A drop in luminance and a drop in contrast in the synthesized
image (first synthesized image II or second synthesized image 12) is
also suppressed in this example. The security image 12 can therefore
be easily recognized in the synthesized image (first synthesized image
II or second synthesized image 12) . Furthermore, because the security
image 12 appears as a low luminance black color in the second synthesized
I
i
26
image 12, the security image 12 can be easily recognized.
[0081J
Other embodiments
The check processing system 1 may also be configured with the
image processing uni t 42 of the control device 7 disposed on the check
processing device 5 side. In this case, the image processing unit 42
disposed to the check processing device 5 sends the synthesized image
(first synthesized image II or second synthesized image 12) to the
control device 7. Also in this case, the control unit 31 functions
as the image processing unit 42 as a result of the control unit 31
of the check processing device 5 running an image processing program.
[0082J
Note that the check processing device 5 may also have a pair of
image sensors 16 on opposite sides of the conveyance path 18 at the
image reading position B, and acquire images of both the front and
back of the check 2. An image recognition unit that recognizes text
and images on the face 2a of the check 2 based on the first imageGl
may also be provided.
The invention being thus described, it will be obvious that it
may be varied in many ways. Such variations are not to be regarded
as a departure from the spirit and scope of the invention, and all
such modifications as would be obvious to one skilled in the art are
intended to be included within the scope of the following claims.

Claims:What is claimed is:
1. An image processing device comprising:
an image acquisition uni t that drives an image sensor, acquires
a first image by reading a surface of a medium exposed to a visible
first light, and acquires a second image by reading a surface of the
medium exposed to an ultraviolet second light;
a reverse image generating unit that generates a reversed second
image by reversing light and dark in the second image; and
a synthesizing unit that generates a synthesized image by
combining the first image and the reversed second image.
2. The image processing device described in claim 1, wherein:
the second image includes an image part based on fluorescence
from UV ink.
3. An image processing method comprising:
acquiring a first image by reading a surface of a medium exposed
to a visible first light, and acquiring a second image by reading a
surface of the medium exposed to an ultraviolet second light, by an
image sensor;
generating a reversed second image by reversing light and dark
in the second image; and
generating a synthesized image by combining the first image and
the reversed second image.
4. The image processing method described in claim 3, wherein:
the second image includes an image part based on fluorescence
from UV ink.
5. A program that operates on a control device that controls driving
an image sensor, the program causing the control device to function
as:
28
an image acquisi tion unit that drives the image sensor, acquires
a first image by reading a surface of a medium exposed to a visible
first light, and acquires a second image by readi'ng a surface of the
medium exposed to an ultraviolet second light;
a reverse image generating unit that generates a reversed second
image by reversing light and dark in the second image; and
a synthesizing unit that generates a synthesized image by
combining the first image and the reversed second image. , Description:DESCRIPTION
Image processing device, image processing method, and program