JPH04294682A - Image processor - Google Patents

Abstract

PURPOSE:To specify an image processing device from a reproducing image by attaching a specific pattern hard to identify by human eyes on an output image signal. CONSTITUTION:The AND gate 913 of a pattern attaching circuit takes the AND of the high-order bit CNO 1 and the inversion signal of the low-order bit CNO 0 of a plane sepuential signal of two bits, and it is sent to an AND gate 911. The signal is effective only when it is CNO=2 i.e., print in yellow is performed at present. Meanwhile, registers 906-909 hold values P1-P4 in advance, and select either the values P1-P4 corresponding to a pattern level selection signal PS from a CPU, and attach a pattern on an input signal V by an adder 912 via the gate 911, and outputs V'. Resolution is set at 400dpi and the pattern is attached at every 32.5mm, however, since the width of a Japanese note is 76mm, and that of each main country is around 60-120mm, the pattern is always attached on the inside when it is copied, which enables the machine number of a copying machine used in copying to be specified.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus such as a copying machine, which has a function of adding a specific pattern to a reproduced image.

0002

[Prior Art] Conventionally, with the development of color copying machines, certain originals (for example, securities/banknotes) that should not be copied
It has become possible to make high-quality copies of images that are almost indistinguishable from the originals, and there is a fear that this will be misused.

0003

[Problem to be Solved by the Invention] However, in the past, when a specific manuscript that should not have been copied was copied and the copy was misused, the copying machine that made the copy or the person who made the copy was Could not be identified.

[0004] The present invention has been made in view of such prior art, and it is an object of the present invention to provide an image processing device that can identify the image processing device from a reproduced image.

[0005]

Means and Effects for Solving the Problems In order to solve the above problems, an image processing device of the present invention electrically processes a full-color image signal to obtain an output image signal, and the image processing device It is characterized by adding a specific pattern to the signal that is difficult for the human eye to discern.

The present invention will be explained in detail below based on preferred embodiments.

[0007] In the following embodiments, a copying machine is shown as an example of application of the present invention, but the present invention is not limited to this, and it goes without saying that the present invention can be applied to various other devices such as scanners and printers.

(First Embodiment) [Apparatus Overview] FIG. 2 shows an overview of the apparatus according to the first embodiment of the present invention. In FIG. 2, reference numeral 201 is an image scanner section, which reads an original at a resolution of 400 dpi (dots/inch) and performs digital signal processing. Further, 202 is a printer unit that prints out an image corresponding to the original image read by the image scanner 201 on paper in full color at a resolution of 400 dpi.

In the image scanner 201, 20
0 is a mirror pressure plate, and document table glass (hereinafter referred to as platen) 2
The original 204 on 03 is illuminated by a lamp 205, guided by mirrors 206, 207, and 208, and focused by a lens 209 onto a 3-line CCD sensor (hereinafter referred to as CCD) 210, which displays full color information of red (R) and green. (G
), which 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
is the electrical scanning (main scanning) of the line sensor at a speed of 1/2v.
By mechanically moving in a direction perpendicular to the direction, the entire surface of the document is scanned (sub-scanning).

In the signal processing section 211, the read image signal is electrically processed and separated into magenta (M), cyan (C), yellow (Y), and black (Bk) components, and then sent to the printer section. Send to 202. Also, for each scan of a document by the image scanner 201, M, C, Y
, Bk is sent to the printer unit 202, and one reproduction image is printed by scanning the original four times in total.

M, C, Y, and Bk image signals sent from the image scanner section 201 are sent to a laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the sent image signal. The laser beam is transmitted through a polygon mirror 214, f
- through the θ lens 215 and mirror 216, the photosensitive drum 2
17.

Reference numeral 218 denotes a rotary developing device, which includes a magenta developing section 219, a cyan developing section 220, a yellow developing section 221,
It is composed of a black developing section 222, and four developing sections alternately contact the photosensitive drum 217 and develop an electrostatic image formed on the photosensitive drum with toner.

Reference numeral 223 denotes a transfer drum, which winds the paper supplied from the paper cassette 224 or 225 around the transfer drum 223, and transfers the image developed on the photosensitive drum onto the paper.

After the four colors M, C, Y, and Bk have been sequentially transferred in this manner, the paper passes through the fixing unit 226, and after the toner is fixed on the paper, it is discharged.

[Image Scanner] FIG. 1 shows a block diagram of the image scanner section 201.

210-1, 210-2, 210-3 are red (R), green (G), and blue (B), respectively.
This is a CCD (solid-state image sensor) sensor with spectral sensitivity characteristics of A.
After being subjected to /D conversion, each signal is output as an 8-bit output signal from 0 to 255.

Sensor 210 used in this embodiment
-1, 210-2, 210-3 are arranged in parallel with a certain distance apart, so delay elements 401 and 4
02, the spatial deviation is corrected.

Log converters 403, 404, and 405 are constructed of look-up table ROM or RAM, and convert luminance signals into density signals. 406 is a known masking and UCR (undercolor removal) circuit;
Based on the three input signals, magenta (M), cyan (C), yellow (Y), and black (Bk) signals are sequentially output with a predetermined bit length, for example, 8 bits. Because of this sequential protrusion, the CCD sensors 210-1 to 21
0-3 performs four scans.

Reference numeral 407 denotes a known spatial filter circuit, which corrects the spatial frequency of the output signal. Reference numeral 408 denotes a density converting means, which corrects the density characteristics of the printer section 202, and is composed of a ROM or RAM similar to the log converters 403 to 405.

On the other hand, 414 is a microcomputer (hereinafter referred to as CPU) that controls the device, and 413 is a CPU.
It is an input/output port (hereinafter referred to as an I/O port) connected to U414, and 409 is a specific document determining means.

Here, the specific document determining means 409 determines the possibility that the document placed on the document table is at least one of a plurality of predetermined specific documents, and outputs a determination signal H indicating this possibility. is output in multilevel 2-bit format. That is,
If there is a strong possibility that it is at least one of the plurality of specific originals, H="3" is output, and when this possibility is the least, H="0" is output.

The CNO signal is a 2-bit field sequential signal, and is a control signal that indicates the order of four reading operations as shown in Table 1.
, and switches the operating conditions of the masking/UCR circuit 406.

[0023]

[Table 1] Further, the above-described frame sequential signal CNO is also input to the determination means 409, and the determination criteria can be switched for each of the four reading operations to perform determination on a different specific document.

410 is a pattern adding circuit, and CP
In response to the 2-bit pattern level selection signal PS specified by U414, a pattern that is difficult for the human eye to discern is added to the copied image.

[Timing Chart] FIG. 6 shows a main scanning timing chart in this embodiment. VSY
The NC signal is a sub-scanning section signal, and is a signal indicating the sub-scanning image output section. HSYNC is a main scanning synchronization signal, and is a signal for synchronizing the start of main scanning. CLK is
This is an image transfer clock, and is a basic clock for various image processing in this embodiment.

On the other hand, CLK4 is a signal obtained by dividing the CLK signal by 1/4, and serves as a basic clock in the determining means 409. The SEL signal is a timing signal used in the thinning circuit 301 described above, and is shown in FIG. 4(b).
It is generated by a circuit like the one shown in . That is, inverter 4
51, a 2-bit counter 452, an inverter 453, and an AND gate 454. 2 bit counter 4
52, by the HSYNC signal which is the main scanning synchronization signal,
After being cleared (initialized), count the CLK signal,
The count value is output in 2 bits. (D0, D1)
The upper bit D1 is outputted as the CLK4 signal, and the AND of the inverted signal of the lower bit D0 and the upper bit D1 is outputted as the SEL signal.

As a result, in the circuit shown in FIG. 4(a), the flip-flop 45 that holds data using the CLK signal
As shown in FIG. 6, the CLK signal is It is possible to obtain an R' (or G', B') signal that is thinned out at a rate of 1/4 from the R (or G, B) signals transferred as a signal and synchronized with CLK4. .

[Determination Means] FIG. 3 shows a block diagram of the determination means 409.

A decimation circuit 301 as shown in FIG. 4 decimates data in order to reduce the load on the processing circuit of the determination means. A color matching lookup table ROM (read-only memory) 302 performs color matching with a plurality of types of specific originals.

The color distribution of 32 types of specific originals is checked in advance, and the results of determination as to whether the color of the relevant pixel matches the color of those specific originals are stored.

That is, the CNO signal, which is a frame sequential signal, is input to the ROM 302 in the upper 2 bits of the address, and the upper 5 bits of the thinned out RGB color image signals are input in the lower 15 bits. Value of each side sequential signal CNO is 0
- 3, whether or not the color tone of the pixel matches the color tone of 8 types of specific documents is simultaneously output in correspondence with 8-bit data, and a total of 32 types of specific documents are detected in 4 reading scans. Make judgments about

303-1, 303-2, ..., 303
-8 is a color judgment circuit composed of the same hardware, including an integrator 306, registers 307, 308,
309 and a comparator module 310, each of which determines the possibility that a specific document exists in the document using two bits. 309 is a maximum value circuit, and the color judgment circuit 3
The maximum value of the determination result outputs of 03-1 to 303-8 is output. That is, the determination result for the one with the greatest possibility of existing among the eight types of specific originals is output.

[Integrator] FIG. 5 shows a block diagram of the integrator 306. 501 and 505 are flip-flops that hold data at the rising timing of the CLK4 signal.

A multiplier 502 inputs two 8-bit input signals (A, B) and outputs an 8-bit signal (A×B/255) as a multiplication result. 503 is also a multiplier, and inputs a 1-bit input signal (A) and an 8-bit input signal (A).
B), and the multiplication result is an 8-bit output signal (A
×B) is output.

An adder 504 inputs two 8-bit input signals (A, B) and outputs an 8-bit signal (A+B) as the addition result.

As a result, in this integrator, an 8-bit output signal yi for a binary input signal xi is expressed by the following equation.

yi = (α/255) yi-1+βxi-1 where α and β are constants set in advance, and the various characteristics of the integrator are determined by the magnitudes of these values.

For example, FIG. 7 shows an example of the input and output of this integrator in the case of α=247 and β=8. That is, (a)
In response to an input xi-1 as shown in (b), an output yi as shown in (b) is output.

Here, inputs such as 701 and 702 that are "1" even though the surrounding areas are mostly "0",
Even though the surrounding area is mostly “1” like 703, “
0" is considered to be noise. This is processed by an integrator and stored in the register 307 in FIG.
) By setting an appropriate threshold value such as yi and binarizing the output yi of the integrator, noise can be removed.

[Comparator Module] FIG. 8 shows a block diagram of the comparator module 310. 801, 802, 80
3 is a comparator, 804 is an inverter, 805 is an AN
D gates 806 and 807 are OR gates. In advance,
A value R1 is set in the register 307, a value R2 is set in the register 308, and a value R3 is set in the register 803.
There is a relationship of >R2>R3. With this configuration, as a result, the determination result is quantized into 2 bits and output. That is, if R1<(input), 11 is output, if R2<(input)≦R1, 10 is output, and if R3<(input)≦R
2, 01 is output, and (input)≦R3, 0
0 is output.

[0041] This output signal indicates the possibility that the input image is a specific original.

[Pattern Addition Circuit] FIG. 9 shows a block diagram of the pattern addition circuit 410. 901 is a sub-scanning counter, 902 is a main-scanning counter, 903 is a look-up table ROM, 905 is a flip-flop, 91
3 is an AND gate, 906, 907, 908, 909 are registers, 910 is a 4to1 selector, 911 is an AN
A D gate, 912 is an adder, 913 is an AND gate, and 914 is an inverter.

Here, the sub-scanning counter 901 repeatedly counts the main-scanning synchronizing signal HSYNC, and the main-scanning counter 902 repeatedly counts the pixel synchronizing signal CLK with a width of 9 bits, that is, 512 cycles. Furthermore, 903 is a read-only memory (hereinafter referred to as RO) in which a pattern to be added is held.
M), a sub-scanning counter 901, a main-scanning counter 9
The lower 6 bits of each count value of 02 are input. Only one bit of the output of the ROM 903 is referenced, and the AND gate 904 performs a logical product of the upper three bits of the main scanning counter 901 and the sub-scanning counter 902, and synchronization is performed with the CLK signal in a flip-flop 905. , AND gate 913, the upper bit of the 2-bit frame sequential signal is set to CNO1, and the lower bit is set to CNO1.
If it is NO0, it is sent to AND gate 911 after being logically ANDed with both the inverted signal of CNO0 and CNO1. This signal is valid only when CNO=2, that is, when yellow is currently being printed.

On the other hand, registers 906, 907, 908,
909 holds values P1, P2, P3, and P4 in advance, and one of P1 to P4 is selected according to the pattern level selection signal PS specified by the CPU, and the AND gate 911 is selected. After that, an adder 912 adds a pattern to the input signal V and outputs V'. Therefore, when CNO=2, that is, when yellow is currently being printed, the pattern held in the ROM 903 is repeatedly read out and added to the signal to be output.

Here, it is set so that P1<P2<P3<P4, and the selector 910 is set such that when s=00 (binary number), Y=A, and when s=01 (binary number), Y=B s When = 10 (binary number), Y = C. When s = 11 (binary number), Y = D. Therefore, when PS = 00 (binary number), V' = V + P1 PS =
When 01 (binary number) V'=V+P2PS=10(
When V'=V+P3 (binary number) When PS=11 (binary number) A pattern is added so that V'=V+P4.

[0046] Here, the added pattern is added using only yellow toner so that it is difficult for the human eye to discern. This takes advantage of the fact that the discrimination ability is weak. Furthermore, by varying the level of the added pattern depending on the possibility that a specific document exists in the input image,
In a normal copy, the pattern is hardly discernible to the human eye, and the more likely it is that a specific document exists, the more clearly the pattern is added.

[Copy Result] FIG. 10 shows an example of the copy result in this embodiment. The added pattern is indicated by 1001, and the contents held in the ROM 903 are added. In the example shown in FIG. 10, “ABCD1234
``6 patterns are difficult to discern for the human eye.
Added in a pattern of 4 pixels x 64 pixels, main scanning 512 pixels
It is repeated every pixel and every 512 sub-scanning lines. Therefore, by using a serial number unique to the machine or an encoded version of the serial number, the copying device can be identified by identifying the copy.

Furthermore, if there is a high possibility that a specific document that should not be copied exists in the read image,
It is also possible to add sharp patterns. That is, the density of the pattern can be changed depending on the possibility that the document is a specific document.

Furthermore, in this embodiment, the pitch at which patterns are added is set at every 512 pixels (or lines) in the main scan, but in this embodiment, the pitch is set at 400 dpi (dots/line).
Since the resolution is 1 inch), a pattern is added every approximately 32.5 mm. On the other hand, the width of banknotes (Bank of Japan notes) in the lateral direction is about 76 mm, and the width of banknotes of major countries in the lateral direction also ranges from about 60 mm to 120 mm.
Since it is between mm, when a banknote is copied,
This pattern will always be added to the inside of the copied banknote. Therefore, even if only a portion of the banknote is cut off and misused, the copy can be identified and the machine number of the copying machine used to make the copy can be identified by reading the added pattern.

[Flowchart] In FIG. 11, the CPU 41
Among the device controls controlled by 4, the pattern level selection signal PS
1 shows a flowchart for a set of .

First, immediately after starting copying, step 1
At 102, the pattern level selection signal PS is set to “0”.
Set. Next, in step 1103, the current determination level H and the value of PS are compared, and if H is larger, the value of H is set in PS in step 1104. Otherwise, return to 1103. That is, according to the history of the judgment signal H, the maximum value from the copy start to the present is P.
Set to S.

(Second Embodiment) The present invention is not limited to the first embodiment described above. For example, in the first embodiment, the specific pattern to be added is the device's unique serial number or an encoded version of this, but the information is not limited to this as long as it is information for identifying the device. .

For example, other information for identifying the device may be used, such as the manufacturing date of the device, the lot number of the device, and the version of the device.

(Third Embodiment) In the first and second embodiments, the device that made the copy was specified, but the present invention is not limited to this, and does not limit the person who made the copy. There may be.

[0055] For example, devices that require the insertion of an ID card to limit the number of users and devices that require the input of an ID number are already known. In the device, a recognized ID number or an encoded version thereof may be added as a specific pattern.

[0056] Furthermore, the date of copying or a code thereof may be added as a specific pattern.

As explained above, according to the above embodiment of the present invention, as a method for identifying the device, a specific pattern that is difficult to identify with the human eye is added to the copy. If a specific document (for example, a banknote) that should not be copied is copied, this can be used as a clue to limit the device that made the copy. Furthermore, by repeatedly adding a specific pattern at a pitch shorter than the width of the banknote, even if a part of the copy is cut out and misused, the specific pattern will always be added to the copy. By limiting this, the device that made the copy or the person who made the copy can be determined. Or you can narrow it down.

In the above embodiment, a laser beam printer was used as an example, but the present invention can also be applied to an inkjet printer or a thermal transfer printer.

In particular, a so-called bubble jet type printer using a type of head that ejects droplets using film boiling caused by thermal energy may be used.

Further, the color to be added is not limited to yellow, but may be an inconspicuous color such as yellow-green or gray, or a color with high brightness such as light purple or light green.

[0061] Furthermore, the document is not limited to a document input by a reader, but may be a document input by a still video camera, a video camera, or even a document created by computer graphics.

[0062]

As described above, according to the present invention, it is possible to identify from a reproduced image the image processing apparatus that reproduced the image.

[Brief explanation of drawings]

[Figure 1] Block diagram of image scanner section

[Fig. 2] External view of the device in the first embodiment

[Figure 3] Block diagram of determination means

[Figure 4] Block diagram of thinning circuit and frequency dividing circuit

[Figure 5
] Integrator block diagram

[Figure 6] Timing chart

FIG. 7 is a diagram showing the timing of input and output signals in the integrator 306.

FIG. 8 is a block diagram of comparator module 310.

[Figure 9]
Block diagram of pattern addition circuit 410

FIG. 10 is a diagram showing an example of copying results in this embodiment.

[Figure 11] Flowchart showing the flow of control

[Explanation of symbols]

202 Image scanner section 203 Printer section 306 Integrator 308 Comparison module 409 Specific manuscript determination means 410 Pattern addition circuit 414 CPU

Claims (8)

[Claims] 1. An image processing device that electrically processes a full-color image signal to obtain an output image signal, characterized in that a specific pattern that is difficult to discern to the human eye is added to the output image signal. Processing equipment. 2. Claim 1, further comprising an image reading means for optically reading the original to obtain color-separated full-color image signals, and an image outputting means for printing out the processed output image signals. The image processing device described. 3. The image processing apparatus according to claim 1, wherein the specific pattern is an identification number or code unique to the mounting. 4. The image processing device according to claim 1, wherein the specific pattern is a serial number or code that can limit the device. 5. The image processing device according to claim 1, wherein the specific pattern represents a manufacturing date of the device. 6. Claim 1, wherein the specific pattern is repeatedly added to the output image at a constant cycle.
The image processing device described. 7. The image processing apparatus according to claim 6, wherein the certain period is a period smaller than the lateral width of the banknote. 8. The output image signal is a signal separated into three color components of magenta, cyan, and yellow, or a signal separated into four color components obtained by adding black to the three color components, and the specific pattern The image processing apparatus according to claim 1, wherein is added to a yellow color component.