JP2994656B2 - Image processing device - Google Patents

Description

The present invention relates to an image processing apparatus.

[Prior Art] Conventionally, with the colorization of an image processing apparatus represented by a copying machine, there is a concern that counterfeiting of a specific document, especially a bill, may occur.

[Problems to be Solved by the Invention] In response to the above-mentioned fears, a copying apparatus has been proposed which determines the above-mentioned specific document and controls the copying process based on the result of the determination.

However, in such a copying apparatus, a configuration for detecting the characteristics of the original is provided separately from the configuration for forming the latent image by directly using the reflected light from the original in the copying process, and this configuration determines whether the original is a specific original. Since the judgment is made, there is a problem that the judgment is disturbed by a malicious operator working on this configuration.

On the other hand, when determining a specific document, it is necessary to determine the characteristics of the specific document. However, when a portion where the gradation change of the specific document is small is used for the determination, the time change of the specific document (dirt, etc.) ) Has the problem that the determination cannot always be made satisfactorily.

Further, in a configuration in which a character, a line drawing part, or the like is a determination target and a binary determination result is output, an erroneous determination may occur due to a positional shift of an image to be determined.

An object of the present invention is to provide an image processing device that solves the above problem.

[Means for Solving the Problems] In order to solve the above problems, the present invention relates to an input means (this embodiment) for inputting a plurality of color component signals used for forming a color image in a color image forming apparatus for forming a color image. Then, for example, FIG. 4 corresponds to 408), storage means for storing reference data used to determine whether or not a red seal having a character area included in a specific image exists in the color image (in this embodiment, for example, ROM418 A determination result of determining the similarity between the reference data and a predetermined area in the color image using the plurality of color component signals, and controlling whether to prevent forgery prevention in the color image forming apparatus. Output means (in this embodiment,
As a result of FIGS. 10 and 1009, FIG.
(Equivalent to PU).

〔Example〕

 Hereinafter, the present invention will be described based on preferred embodiments.

In the following embodiments, a copying apparatus is shown as an application example of the present invention. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to various other apparatuses.

FIG. 2 shows an external view of the apparatus according to the first embodiment of the present invention.

In FIG. 2, reference numeral 201 denotes an image scanner which reads an original and performs digital signal processing. Reference numeral 202 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner 201 on a sheet in full color.

In the image scanner unit 201, reference numeral 200 denotes a mirror pressure plate, and a document 204 on a platen glass (hereinafter, platen) 203 is
Irradiated by a lamp 205, guided to mirrors 206, 207, and 208, forms an image on a three-line sensor (CCD) 210 by a lens 209, and outputs full-color information red (R), green (G),
The signal is sent to the signal processing unit 211 as a blue (B) component.
Note that 205 and 206 are speeds v, and 207 and 208 are 1/2 v mechanically move in the direction perpendicular to the electrical scanning direction of the line sensor to scan the entire original. The signal processing unit 211 electrically processes the read signal, decomposes the signals into magenta (M), cyan (C), yellow (Y), and black (Bk) components, and sends them to the printer unit 202. In addition, for one original scan (scanner) in the image scanner unit 201, M,
One component of C, Y, Bk is sent to the printer unit 202,
One printout is completed by a total of four document scans.

M, C, Y or sent from the image scanner 201
The Bk image signal is sent to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. Laser light is polygon mirror 214, f-θ lens 2
15. Scan the photosensitive drum 217 via the mirror 216.

Reference numeral 218 denotes a rotary developing unit, which includes a magenta developing unit 219, a cyan developing unit 220, a yellow developing unit 221, and a black developing unit 222. The four developing units alternately contact the photosensitive drum 217 and are formed on the photosensitive drum 217. The developed electrostatic latent image is developed with toner.

Reference numeral 223 denotes a transfer drum which winds a sheet fed from the sheet cassette 224 or 225 around the transfer drum 223 and transfers an image developed on the photosensitive drum 217 to the sheet.

After the four colors M, C, Y, and Bk are sequentially transferred in this manner,
The sheet passes through the fixing unit 226 and is discharged.

In the following, in this embodiment, a description will be given in detail of an example of a manuscript which is a target of forgery prevention, for example, a forgery prevention function of a 10,000 yen note of the Bank of Japan. However, the present invention is not limited to such a target. Of course.

In this embodiment, copying is performed in a total of four reading operations (scans) as described above. However, the image scanner 201 and the printer 202 in each scan are used.
3 is shown in FIG.

In other words, when counterfeiting of a 10,000-yen bill is to be prevented, at the time of the first scan, the image scanner detects the approximate position of the watermark of the 10,000-yen bill in mode 1; The printer section outputs magenta.

At the time of the second scan, the image scanner detects the correct position and the placed angle in the mode 2 mode.

At the time of the third scan, the image scanner is in the mode 3 and calculates the position of the red seal of the 10,000-yen bill calculated from the position and angle detected in the second scan. Extract and save to memory,
It is determined whether it is a red seal. The printer outputs yellow.

At the time of the fourth scan, the image scanner is in the mode 4 state, and when it is determined that forgery is to be performed at the time of the third scan, specific processing for preventing forgery is performed.

FIG. 5 is a timing chart showing the operation of each unit in the image scanner unit of this embodiment.

The VSYNC signal is an image valid section signal in the sub-scanning direction, and generates an output signal of (C), (M), (Y), and (Bk) for performing image reading (scanning) in the section of “1”. I do. VE is an image effective section signal in the main scanning direction,
The image is valid in the section “1”. The HSYNC signal is a main scanning synchronization signal, and takes a timing of a main scanning start position in a section “1”. The CLK signal is a pixel synchronization signal, and transfers image data at the rising timing of 0 → 1. CLK16 is a timing signal every 16 pixels.
At the rising timing of 1, the timing of the signal subjected to the 16 × 16 block processing described later is set.

[Image Scanner Unit] FIG. 4 shows the internal blocks of the image scanner 201. 210-1, 210-2 and 210-3 are CCDs having spectral sensitivity characteristics of red (R), green (G) and blue (B), respectively. Is output.

Sensors 210-1, 210- used in the present embodiment
2, 210-3 are arranged at a distance as shown in FIG. 1, so that the spatial displacement of the delay elements 401 and 402 is corrected.

403, 404, 405 are log converters, look-up table RO
M, and the luminance signal is converted into a density signal. Four
Reference numeral 06 denotes a well-known masking and UCR circuit. Although detailed description is omitted, Y, M, C, and Bk signals for output are sequentially converted into predetermined bits at each reading operation by the input three primary color signals. It is output in long, for example, 8 bits.

An OR gate circuit 407 performs a logical OR operation on the value held in the register 408. Register 408 typically contains OO _H
There have been written, the output of 406 is directly output to the printer unit, during the anti-counterfeit processing, fill it with toner by previously excisional the FF _H CPU 417 is in the register 408 via the data bus Image can be output.

A CPU 417 controls the device in each mode.
A window comparator 408 determines whether or not a specific level signal specified by the CPU 417 has been input. In modes 1 and 2, the background level is detected, and in mode 3, a red mark is detected. Blow processing circuit 409
Then, 16 × 16 block processing is performed, and the output of the window comparator 408 is processed for each 16 × 16 block.

Reference numeral 412 denotes a readable / writable random access memory (RAM). The selector 411 switches the data, and the selector 413 switches the address.

On the other hand, a main scanning counter 419 is reset by the HSYNC signal, is counted up at the timing of the CLK signal, and has a 13-bit main scanning address (hereinafter referred to as X address) X12.
Generates ~ X0.

Reference numeral 420 denotes a sub-scanning address counter, which is reset in the period of "0" of the VSYNC signal and is counted up at the timing of the HSYNC signal to generate a 13-bit sub-scanning address (Y address) Y12 to Y0.

The CPU 417 selects selectors 411, 413, 415, 41 according to each mode.
6. Control the address decoder 414 to read / write data from / to the RAM 412. 418 is R added to CPU 417
AM / ROM. Reference numeral 410 denotes a watermark detection circuit that detects a watermark portion of a bill.

FIG. 6 is a block diagram of the window comparator 408 shown in FIG. Reference numerals 601, 602, 603, 604, 605, and 606 are registers directly connected to the data bus of the CPU 417, and a desired value is written by the CPU 417.

Reference numerals 607, 608, 609, 610, 611, and 612 denote comparators, whose outputs become 1 only when A> B is satisfied with respect to inputs A and B.

An AND gate 613 outputs 1 only when the outputs of all the comparators become 1, and outputs 0 otherwise. Now, when the values R _H , R _L , G _H , G _L , B _H , and B _L are written in the registers 601, 602, 603, 604, 605, and 606 respectively,
Window comparator only when _RL <R < _{RH, GL} <G < _GH, and _BL <B < _BH for input signals R, G, B
The output of 408 is "1", otherwise it is "0".

FIG. 7 is a diagram showing the internal details of the block processing circuit 409 shown in FIG.

701,702,703,…, 714,715 are 15 Ds arranged in series
This is a flip clock (hereinafter referred to as DFF), which sequentially delays the input signal with the pixel clock CLK signal, and VE = "0"
That is, it is cleared to "0" in the non-image section.

738 is a 5-bit up-down counter, 737 is an OR gate,
740 is an AND gate, and the operation is based on the following table.

That is, the output of the counter 738, VSYNC or VE is cleared to 0 in the interval of "0" is held at the time of X _t = X _t-15, is counted up-when the X _t = 1 and X _t-15 = 0 When _Xt = 0 and _Xt-15 = 1, the countdown is performed.

That is, as a result outputs the sum of the 16 data X _t ~X _t-15 (= the number of 1).

Further, the output is passed through DFF739 to a first-in-first-out memory (FIFO) 72 per line.
1,722,723,..., 734,735, the data for 16 lines are simultaneously input to the adder 741, and the sum is output. As a result, the sum SUM of the number of 1s in the 16 × 16 window is output as 0 to 256.

A digital comparator 742 compares the output SUM of the adder 741 with a comparison value TW predetermined by the CPU 417, and outputs the result as "0" or "1".

Therefore, by setting an appropriate value in TW in advance, 16
Noise removal can be performed in units of × 16 blocks.

 FIG. 8 is a diagram for explaining the watermark detection circuit 410.

.., 821 are 18 FIFOs, each of which gives a delay of 1 line and 19 lines are processed simultaneously.

801,802,803,…, 804,805,806,807,…, 808,…, 809,81
0,811, ..., 812, ..., 813,814,815, ..., 816 are DFFs arranged in series of 10 for each of 19 lines of output, and ... 817,818 are arranged in series of 9 more after the DFF812. DFF, all DFFs are driven by CLK16. A
After passing through ND gates 823,824,825, DFF804,808,…, 812,816
(Fresh 19) block) and DFF809,810,811,812,817,818
1 when the output of all (width 19 blocks) is "1"
Is output, and the Position at that time is latched and sent to the CPU.

 FIG. 9 is a block diagram of the address decoder 414.

Reference numerals 901, 902, 903, 904, 905, 906, 907, 908 and 909 are registers connected to the data bus of the CPU, and a desired value is written by the CPU.

Since 910, 911, 912, and 913 all have the same structure, only 910 will be described.

Reference numerals 914 and 915 denote subtracters, which output AB for inputs A and B, and the MSB of the output is a sign bit. When the output becomes negative, it is output as MSB = 1.

916 and 917 are comparators, and for inputs A and B, A <B
In this case, "1" is output. However, A
When the MSB is “1”, “0” is output regardless of the input of B.

918, 919, and 920 are AND gates, respectively, when the value BXY is written to the register 909 as a result. Only when Is output.

Similarly in 911 Only when is the output X2 = X address−RX2 Y2 = Y address−RY2 E2 = 1 is output.

Similarly in 912 Only when is the output X3 = X address−RX3 Y3 = Y address−RY3 E3 = 1 is output.

Similarly in 913 Only when, X4 = X address−RX4 Y4 = Y address−RY4 E4 = 1 is output.

914, 915, 916, 917, and 918 are OR gates, respectively, and the conditions (1), (2), (3), and (4) are set when RX1, RY1, ..., RX4, and RY4 are set so that two or more are not satisfied at the same time. Outputs one of X1, X2 ... X4, 917 outputs "1" when any of the conditions are satisfied, and 918 outputs one of Y1, Y2 ... Y4 Is output.

 Also, it is output from 915,916 as shown in the following table.

[Processing Flow] FIG. 3 shows four scans from the first scan to the fourth scan in the present apparatus, four modes from mode 1 to mode 4 in the image scanner, and outputs from the printer unit. Show the contents.

FIG. 10 shows a processing flow under CPU control. Tenth
In the figure, 1001 is the mode 1 for the first scan
CPU is set. In mode 1, the printer outputs magenta and detects the approximate position of the watermark in the bill. For this purpose, the CPU stores, in the window comparator 408, a register 601 to 6 shown in FIG.
Write to 06.

In this state, at 1002, the first scan is started.

FIG. 1 shows a state in which a 10,000-yen bill is placed on the platen. In the first scan, that is, in mode 1, the output of the window comparator is indicated by a hatched portion in FIG. At "1".

Further, in the water content, since this continues for a certain number of pixels in the vertical / horizontal direction, the address corresponding to (Xc, Yc) in the part corresponding to (Xc, Yc) in FIG. And sent to the CPU.

The CPU can roughly know the value of (Xc, Yc), which is the center of the bill.

Next, in FIG. 10, at 1003, a setting for mode 2 is performed. That is, in the mode 2, the selector 411 is set to A, the selectors 413 and 415 and 416 are set to the A side. Write a value in advance.

At this time, in the second scan of 1004, RAM4
In T, if T is set to a value corresponding to about 128 mm, a bit map in which only the hatched portion is "1" in the broken line portion can be obtained. Note that 128 mm is set as a numerical value such that the bill is included within the broken line shown in FIG. 1 irrespective of the bill type and the mounted angle.

Further, the CPU 417 detects the exact position and angle of the bill at 1005 from the bit map. At that time, the CPU selects the selector 411 as C and 413 as B, and reads the contents of the RAM 412 freely. FIG. 10 shows the principle, but a method of detecting four corners around a bill is employed. In other words, when placed as shown in FIG. 11, Also, The four corners are detected using the fact that

Although detailed description is omitted, four corners can be detected at any angle by selectively using either the condition (5) or the condition (6).

So in Figure 1 The angle θ is also calculated by the following equation.

Further, the position of the red seal is determined from the obtained angle and position. Since the banknotes are placed either upward, downward or back / front, (X _S1 , Y _S1 ), (X _S2 ,
One of (Y _S2 ), (X _S3 , Y _S3 ), and (X _S4 , Y _S4 ) is the position of the red mark. These are calculated by (X ₀ , Y ₀ ) and θ by a simple calculation.

Next, in step 1006, mode 3 for the 3rd scan is set. That is, the selector 411 is set to B, the selector 413 is set to A, and the selectors 415, 4
16 is set to B.

In the address decoder 414, the position of the red mark is RX ₁ = X _S1 RY ₁ = Y _S1 RX ₂ = X _S2 RY ₂ = Y _S2 RX ₃ = X _S3 RY ₃ = Y _S3 RX ₄ = X _S4 RY ₄ = Y _S4 (1 pixel unit), and the number of pixels corresponding to about 30 mm which sufficiently covers the red seal in FIG. 1 is set in BXY.

Next, a value for outputting 1 only in the red portion of the red seal is set in each register in the window comparator 408 shown in FIG.

Next, at 1007, the third scan is performed.
The output of the window comparator 408 is written to the RAM 412 at four locations which are considered to be the positions of the red seals in FIG.

Further, in 1008, a red seal is extracted by an algorithm described below and determined in 1009, and if there is no possibility of forgery, that is, if no red seal is detected, a 4th scan is performed in 1010 and Y is performed in a normal operation. , M, C, Bk
, And is fixed and output at 1012.

On the other hand, if it is determined in 1009 that there is a possibility of forgery, that is, if a red seal is detected, forgery prevention or the like is performed in 1011. More specifically, by setting FF _H in the register of FIG. 4 (usually setting OO _H ), FF _H is sent to the printer unit, and Bk toner adheres to the entire surface. , You cannot copy.

[Pattern Matching] Next, pattern matching of 1008 red seal will be described in detail.

Note that the red seals of the banknotes are different between the front and the back, so that two types of red seals are registered in advance when performing pattern matching in order to distinguish one type of banknote.

When a specific part of a specific manuscript is written to RAM 412,
The CPU 417 performs a pattern matching operation with reference to the contents of the RAM 412. FIG. 12 shows a flowchart for pattern matching. The RAM 412 stores four types of binary data as candidates for a specific part. These are named Area 1 to Area 4.

First, the processing after 2102 is performed on the area 1.
In step 2102, window processing for noise removal is performed.

Assume that the binary image of area 1 is 2201. Here, it is assumed that a small square represents one pixel, white blank pixels are white pixels, and hatched portions are black pixels. This is scanned in a 2 × 2 pixel window indicated by 2202, the number of black pixels in the window is counted, and a portion where the count value exceeds 2 is newly set as a black pixel. By doing so, the processing result is reduced to the vertical and horizontal 1/2 each as shown by 2203, and a pattern from which noise has been removed is obtained. Since the number of black pixels in the window at the position 2202 is 1, it is replaced at the position 2204 as a white pixel.

 Next, the position of the center of gravity of the pattern of 2203 is calculated.

This can be calculated by a well-known method by projecting the pattern of 2203 in the vertical and horizontal directions.

Next, the similarity is calculated by standard pattern matching. First, in step 2105, a standard pattern registered in advance as a dictionary is loaded into the CPU from the ROM 418 in FIG. The standard pattern is the red seal pattern of the target banknote.The pattern extracted up to 2103 may be rotated depending on the angle at which the banknote is placed on the platen. Satisfactory results are not obtained when compared with the pattern.

This state is shown in FIG. Therefore, as the standard pattern, a plurality of patterns obtained by rotating the red seal pattern every several degrees may be created and stored in the ROM in advance, and an appropriate pattern may be selected from these and loaded into the CPU. As a plurality of patterns, for example, a red seal is 0 degrees to 36
Using a total of 24 patterns rotated every 15 degrees to 0 degrees,
As a method of selection, the angle θ at which the banknote is already detected is referred to, and when −8 ≦ θ <8 degrees,
A standard pattern with a rotation angle of φ degrees, a pattern with a rotation angle of 15 degrees when 8 ≦ θ ≦ 24 degrees, a pattern with a rotation angle of 30 degrees when 24 ≦ θ <40 degrees, etc. Can execute the similarity calculation.

Here, there is clearly an uncertainty of 180 degrees between the rotation angle θ of the banknote and the rotation angle of the red seal, so when a standard pattern of rotation angle φ degrees is actually selected, the rotation angle of 180 degrees You also need to select a standard pattern.
In the case of 195 degrees and 30 degrees, 210 degrees must be selected at the same time, and therefore the similarity calculation is always performed twice.

Next, the similarity is calculated in step 2106. For the calculation of the similarity, various methods can be considered. For example, the following method can be considered. As shown in FIG. 15, the pattern extracted up to the above is defined as (a) or the standard pattern of a predetermined rotation angle selected by the above method is defined as (b), and B (i, j), P (i, j). (B (i, j) and P (i, j) take the value of 1 for a black pixel and the value of φ for a white pixel.)
The barycentric coordinates of B (i, j) obtained in FIG. 2104 are represented by (i _BC ,
j _BC ), and the barycentric coordinates of P (i, j) obtained in the same manner are (i
_PC , j _PC ), the similarity COR between the two is given by the following equation.

Represents the exclusive OR of P and B, and equation (1) represents the Hamming distance when the center of gravity of the pattern B (i, j) and the pattern P (i, j) are aligned. The greater the COR, the greater the similarity between the two.

In this embodiment, in order to improve the reliability of the similarity and minimize the occurrence of an erroneous recognition expression or the like, the similarity COR is obtained using Expression (2) obtained by modifying Expression (1).

Where · is the logical product, ▲,
▼ represents the judgment of P. When both P and B are black pixels, C
When OR is added by 2, and when P = 0 and B = 1, 1 is subtracted from COR, and the recognition accuracy can be greatly improved.

When the similarity COR is calculated as described above, the threshold Th obtained in advance in 2107 and the COR are compared.

In the case of COR> Th, it is determined that a red seal exists, and the collation operation ends as a banknote is present (2108).

If COR <Th, it is determined that no red seal exists in the current processing area. If n is smaller than 4,
n is incremented by 1, and the matching operation of 2101 to 2109 is repeated for the next area n. If n = 4 in 2109, it means that the red seal pattern does not exist in any of the first to fourth areas, and the collation operation ends with no bill (2110).

[Other Embodiments] This specification has described prevention of forgery of 10,000 yen bills of the Bank of Japan, but its application range is wide and includes relatively wide background and characteristic patterns such as red seals and patterns. If there is, it can be easily applied to securities, foreign national certificates, new and revised tickets, and the like.

Further, the present invention is not limited to an electrophotographic copying machine, and is also important as a mere image scanner or an additional function as a printer alone.

In this embodiment, the size and the position of the original placed on the original platen are determined before performing the pattern matching with the pre-registered pattern. Even in an apparatus which can sequentially send the same document to the reader unit, the same document may be scanned several times, for example, the document may be reciprocated with respect to the reader unit.

As described above, according to the present embodiment, the position and angle of a banknote or the like is detected by the background portion, the red seal is detected, and the pattern matching is performed, so that the banknote or the like placed at any position and angle is detected. Can be prevented beforehand.

[Effects of the Invention] As described above, according to the present invention, in a color image forming apparatus for forming a color image, a plurality of color component signals used for forming the color image are input, and a reference is made using the plurality of color component signals. Since the data is determined, if the malicious operator modifies the data used for the determination, it will also affect the formed image, and the device is resistant to interference by the malicious operator. Can be provided.

Further, a storage means for storing reference data used to determine whether a red seal having a character area included in the specific image is present in the color image, using the multi-color component signal,
By determining the similarity between the reference data and a predetermined area in the color image, by configuring an output unit that outputs a determination result for controlling whether to perform forgery prevention in the color image forming apparatus, It is possible to reduce a defect that occurs when a portion where the gradation change of the specific document is small is used for the determination, and the determination cannot always be made satisfactorily due to a systematic change (dirt or the like) of the specific document.

[Brief description of the drawings]

FIG. 1 is a diagram showing banknotes placed on a platen, FIG. 2 is a schematic view of the apparatus of this embodiment, FIG. 3 is a diagram showing the relationship between four scans and each mode, and FIG. FIG. 5 is a timing diagram, FIG. 6 is a block diagram of the window comparator shown in FIG. 4, FIG. 7 is a diagram of the block processing unit shown in FIG. 4, and FIG. FIG. 4 is a diagram of the watermark detection unit shown in FIG. 4, FIG. 9 is a diagram of the address decoder shown in FIG. 4, FIG. 10 is a flowchart showing the operation of the device, FIG. 12 to 15 are diagrams for explaining pattern matching. 210-1 to 210-3: CCD 408: Window comparator 412: RAM 417: CPU

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-32322 (JP, A) JP-A-60-229572 (JP, A) JP-A-61-213998 (JP, A) 131877 (JP, A) JP-A-60-215294 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (1)

(57) [Claims] An input means for inputting a plurality of color component signals used for forming a color image in a color image forming apparatus for forming a color image, wherein a red mark having a character area included in a specific image exists in the color image A storage unit for storing reference data used for determining whether or not the color data is used; determining a similarity between the reference data and a predetermined area in the color image by using the plurality of color component signals to prevent forgery in the color image forming apparatus; Output means for outputting a determination result for controlling whether or not to execute the image processing.