JP3459667B2 - Color printer device and color image processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printer apparatus and a color image processing method, and more particularly to detecting forgery of banknotes and securities by color image data sent from an external device to prevent forgery. And a color image processing method.

[0002]

2. Description of the Related Art In recent years, image output devices such as printers have made great progress as the performance and spread of various computers have increased. However, in today's information-oriented society, the need for output images such as full-color images that are mono-color, two-color images, or multi-color images is gradually increasing in addition to the conventional black-and-white output images. There is.

There are many other techniques for producing a color output image, such as a silver salt system, a heat sensitive system, an electrophotographic system, an electrostatic recording system, an ink jet system and a bubble jet system. Color output images are often used in photographs and printed materials (books, advertisements, etc.). Conventionally, color images such as printed matter could not be freely handled by individuals due to equipment and cost. However, as described above, with the spread of computers, color images have become more accessible. Further, image recording devices such as printers for image output have made great progress, and output images of extremely high quality can be obtained. Therefore, nowadays, anyone can easily handle color images.

Due to such technological advances, it has become possible to easily output a color image on ordinary paper. Therefore, it is legal for a color copying machine or a color printer, which is a product of such a technology, to make a copy. It is fully conceivable that it is used for counterfeiting things that are not allowed, such as banknotes, securities, stamps, and revenue stamps.

[0005]

However, at present, a color copying machine having a forgery prevention function incorporated therein is available on the market, but the color printer device is the same as the color copying machine for the following reason. It was difficult to incorporate the anti-counterfeit function. (1) Since the scanner does not include a scanner that optically scans an image original and reads the image data or a frame memory that stores the read image data, the entire image data that has been read once is compared with a predetermined reference image to forge. To detect an action, it is necessary to provide a special frame memory for detecting the forgery action. However, since this leads to an increase in the cost of the device, even if technically possible, such a method cannot be taken from the viewpoint of price competitiveness. (2) Comparing with a predetermined reference image after storing it in the frame memory reduces the printing speed. This reduces the price / performance ratio. Therefore, in the case of a color printer, it has been desired to incorporate a forgery prevention function that solves the above problems.

The present invention has been made in view of the above conventional example, and provides a color printer device and a color image processing method capable of preventing forgery without lowering the printing speed and without requiring a large memory. The purpose is to do.

[0007]

In order to achieve the above object, the color printer device of the present invention has the following configuration. That is, a color printer device that receives a color image signal from an external device to form and output a color image, and input buffer means for inputting the color image signal and buffering an amount formed by a matrix of a predetermined number of pixels. Parameterizing means for dividing a color image signal of a matrix of a predetermined number of pixels buffered by the buffer means into a plurality of small areas, and parameterizing image characteristics for each of the divided small areas; Image features of each small area parameterized by the digitizing means,
Comparing means for comparing the parameterized predetermined features of the forgery prevention target image, and the number and distribution of the small regions including the features of the predetermined image are calculated based on the comparison result for each small region by the comparing device. A discrimination unit that discriminates whether or not the input color image signal includes a characteristic of the predetermined image, and based on a discrimination result by the discrimination unit,
The color image formed by the input color image signal is suppressed so as not to output as it is, the parameterization means, for the parameterization of the features of the image represented by the color image signal, There is binarization means for binarizing the color image signal, and the parameterization of the image feature by the parameterization means, the comparison by the comparison means, and the discrimination by the discrimination means are performed by the input buffer means. A color printer device is provided which is characterized in that the color image signals are sequentially input at the time of input.

[0008]

[0009]

According to the present invention having the above configuration, when color image data is input, the input color image signal of a matrix of a predetermined number of pixels is sequentially divided into a plurality of small areas, and the image is divided into a plurality of small areas. The feature is parameterized by binarizing its color image signal, and the feature of the image of each parameterized small region obtained by this is compared with the feature of the predetermined image of the parameterized anti-counterfeit object, Based on the comparison result for each small area, it is determined whether the input color image signal includes the characteristics of a predetermined image, and finally, based on the determination result, the color image signal formed by the input color image signal is formed. Color images that are not output as they are.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing the structure of an electrophotographic color laser beam printer which is a typical embodiment of the present invention. In the apparatus shown in FIG.
The paper 102 fed from the front end of the paper 102 is gripper 103.
It is nipped by f and held on the outer periphery of the transfer drum 103. In the image carrier (hereinafter referred to as a photosensitive drum) 100,
The latent image formed in each color by the optical unit 107 is developed by each color developing device Dy, Dc, Db, Dn and transferred to the paper on the outer periphery of the transfer drum a plurality of times to form another color image. After that, the paper 102 is separated from the transfer drum 103 and fixed by the fixing unit 104, and the paper discharge unit 1
The sheet is discharged from the sheet discharge tray unit 106 from 05.

Here, the developing devices Dy, Dc, Db, D for the respective colors
n has a rotation support shaft at both ends thereof, and each is held by the developing device selection mechanism unit 108 so as to be rotatable around the shaft. As a result, each of the developing devices Dy, Dc, Db, Dn is
As shown in FIG.
Even if 08 rotates about the rotation axis 110, its posture can be maintained constant. After the selected developing device moves to the developing position, the developing device selection mechanism unit 108 is integrated with the developing device and is a fulcrum 1
The selection mechanism holding frame 109 is pulled toward the photosensitive drum 100 by the solenoid 109a around the center 09b, and is moved toward the photosensitive drum 100.

Next, the color image forming operation of the color laser beam printer having the above structure will be specifically described.

First, the photosensitive drum 1 is charged by the charger 111.
Are uniformly charged to a predetermined polarity, and a latent image of, for example, M (magenta) color is developed on the photosensitive drum 100 by exposure with the laser beam light L, and is developed by a developing device Dm of M (magenta) color. A first toner image of M (magenta) color is formed on 100. On the other hand, the transfer paper P is fed at a predetermined timing, a transfer bias voltage (+1.8 kV) having a polarity opposite to that of the toner (eg, positive polarity) is applied to the transfer drum 103, and the first transfer roller on the photosensitive drum 100 is transferred.
The toner image is transferred to the transfer paper P, and the transfer paper P is electrostatically attracted to the surface of the transfer drum 103. After that, the photosensitive drum 100 causes the cleaner 112 to remove the remaining M.
The (magenta) color toner is removed to prepare for the next color latent image formation and development process.

Next, a second latent image of C (cyan) color is formed on the photosensitive drum 100 by the laser beam L.
Then, the second latent image on the photosensitive drum 1 is developed by the C (cyan) color developing device Dc to form a second toner image of C (cyan) color. Then, the second color of C (cyan)
The toner image of is transferred to the transfer paper P in accordance with the position of the first toner image of M (magenta) color that was previously transferred to the transfer paper P. In the transfer of the toner image of the second color, the transfer paper 103 is transferred to the transfer drum 103 immediately before the transfer paper P reaches the transfer portion.
A 2.1 kV bias voltage is applied.

Similarly, the third and fourth latent images of Y (yellow) and K (black) colors are sequentially formed on the photosensitive drum 100, and the latent images are sequentially developed by the developing devices Dy and Db. The Y (yellow) color and the Bk (black) color third and fourth toner images are sequentially transferred in alignment with the toner image previously transferred to the transfer paper P. In this way, the four color toner images are formed on the transfer paper P in an overlapping state. In transferring the toner images of the third color and the fourth color, bias voltage images of +2.5 kV and +3.0 kV are applied to the transfer drum 103 immediately before the transfer paper reaches the transfer portion.

The reason why the transfer bias voltage is increased each time the toner image of each color is transferred is to prevent the transfer efficiency from decreasing. The main cause of this decrease in transfer efficiency is that when the transfer paper leaves the photosensitive drum 100 after transfer, the surface of the transfer paper is charged with a polarity opposite to that of the transfer bias voltage due to air discharge (the transfer paper carrying the transfer paper is charged). The surface of the drum is also slightly charged), and if this charging charge is accumulated for each transfer and the transfer bias voltage is constant, the transfer electric field decreases for each transfer.

During the transfer of the fourth color, when the leading edge of the transfer paper reaches the transfer start position (including immediately before and after), the fourth toner image of the fourth toner image is generated at an effective AC voltage of 5.5 kV (frequency is 500 Hz). A DC bias voltage +3.0 kV having the same polarity and the same potential as the transfer bias applied during transfer is superimposed and applied to the charger 111. In this way, when transferring the fourth color, when the leading edge of the transfer paper reaches the transfer start position, the charger 1
The operation of 11 is for preventing uneven transfer. In particular, in the transfer of a full-color image, even if slight transfer unevenness occurs, it is conspicuous as a difference in color. Therefore, it is necessary to apply the required bias voltage to the charger 111 to perform the discharge operation as described above. .

After that, when the leading end of the transfer paper P on which the four color toner images are superposed and transferred approaches the separation position, the separation claw 113 is formed.
Comes close to each other and the tip thereof comes into contact with the surface of the transfer drum 103 to separate the transfer paper P from the transfer drum 103. The tip of the separation claw 113 maintains the contact state with the transfer drum surface,
After that, it is separated from the transfer drum 103 and returns to the original position. As described above, the charger 111 operates from when the front end of the transfer paper reaches the transfer start position of the final color (fourth color) to when the rear end of the transfer paper leaves the transfer drum 111, and the accumulated charge on the transfer paper ( The polarity opposite to that of the toner) is removed to facilitate separation of the transfer paper by the separation claw 113 and reduce air discharge during separation. The transfer bias voltage applied to the transfer drum 103 is turned off (ground potential) when the trailing edge of the transfer paper reaches the transfer end position (exit of the nip formed by the photosensitive drum 100 and the transfer drum 103). To do. At the same time, the bias voltage applied to the charger 111 is turned off. Next, the separated transfer paper P is conveyed to the fixing device 104, where the toner image on the transfer paper is fixed and is discharged onto the paper discharge tray 106.

As input data, this device stores computer-generated color image data (for example, data represented by RGB components), or another image data generating device (still image recorder, etc.) and stores something. Image data stored in the medium may be considered.

The color laser beam printer of this embodiment outputs an image at a resolution of 300 dots / inch (dpi) through the image forming process as described above.

In this case, as shown in FIG. 2, the characters and figures have a color portion (.circle-solid.) Having an arbitrary width which is output at a position arranged on a grid of 300 dots / inch for each color.
Mark) and the remaining white part (◯ mark) (here, the part of the character to be recognized as the specific image is represented by the ● mark). FIG. 2 shows an image data pattern of the alphabet character "a".

In the present embodiment, as shown in FIG. 3, for a pixel A to be output (hereinafter, this pixel is referred to as a target pixel), an area S surrounding the target pixel (here, the main scanning direction is 1).
The characteristics of the image data of 1 pixel × 9 pixels in the sub-scanning direction) are examined.

The feature extraction will be described in more detail below.

Of the image data group of the alphabetical character "a" having a resolution of 300 dpi shown in FIG.
And the image data of the area S surrounding the target pixel are stored in a temporary memory (not shown). As a result, the dot information as shown in FIG. 4 is stored. Then, the characteristics of the image data group in the area S are compared with a plurality of image data groups having the same size (11 pixels × 9 pixels) as the area S prepared in advance.

FIG. 5 is a block diagram showing the configuration of a circuit for recognizing a specific image provided in the input section of the printer engine section adapted to the laser beam printer of this embodiment having a resolution of 300 dpi.

In FIG. 5, reference numerals 25 to 33 denote line memories, which store the input image forming signal VDO while sequentially shifting in synchronization with the clock signal VCLK. Each line memory is line memory 25 → line memory 26 → The line memories 27, ..., And the line memory 33 are connected in this order and store dot information of 9 lines of main scanning length in the sub-scanning direction. 34 to 42 are shift registers, and each shift register 34 to 42 is a line memory 25 to 33.
Corresponding to, the output from each line memory is input. As shown in FIG. 5, each shift register has a register unit 1
A matrix memory of 11 pixels in the main scanning direction × 9 lines in the sub scanning direction of a to 1k, 2a to 2k, 3a to 3k, ..., 9a to 9k is configured. In the matrix memory, the pixel set in the central register unit 5f is defined as the pixel of interest.

Generally, when handling a color image,
The data value of each pixel of each color component has at least two or more gradation levels. For the binary image, the image data as it is can be used for the feature extraction for detecting the specific image. However, in the case of a multi-valued image, the multi-valued image must be binarized by a threshold value to some extent to perform feature extraction for detecting the specific image.

FIG. 6 is a diagram showing a density distribution of a certain color component of a multi-valued color image in which one color component of one pixel is represented by 8 bits, that is, 256 gradations of 0 to 255. As shown in FIG. 6, for density values of 0 to 255, the data (density value) of each pixel of the image is generally distributed with a certain spread. However, if a similar density distribution is considered for a certain characteristic image, it is expected that the distribution will be a characteristic feature of the image. For example, in FIG.
A concentration distribution in which a peak appears in the closed interval of the concentration value as indicated by a and b in FIG. In this way, the characteristics of the image can be expressed by paying attention to the density of a certain closed section.

Therefore, in this embodiment, for each pixel of each color component of the input color image data, the data value between a and b in FIG. 6 (of course, the values a and b themselves can be arbitrarily set) is set. The input image data is binarized so that it is set to "1" and the data value of other portions is set to "0".

Therefore, in the color laser beam printer of this embodiment, when the color image data is output from the line memories 25 to 33 to the shift registers 34 to 42, the tint of the specific image serving as a reference for detecting forgery is taken into consideration. Then, an appropriate threshold value or range is set for each color component, the color image data is binarized, and the shift registers 34 to 42 are set.
Output to. To this end, each of the line memories 25 to 33 is provided with a binarization circuit (not shown) for that purpose.
However, for actual color print output, the color image data is output as it is without being binarized.

Reference numeral 43 is a processing circuit for detecting the characteristics of the data stored in the matrix memory for recognizing the specific image and determining whether or not the image is the specific image. The processing circuit 43 includes the register units 1a of the shift registers 34 to 42.
Input 99 bits set to ˜9k and output parallel signal MDT. The parallel signal MDT is input to the parallel / serial conversion circuit 44. The parallel-serial conversion circuit 44 converts the input parallel signal MDT into a serial signal VDOM, and then drives a laser by a laser driver (not shown).

Reference numeral 45 denotes a clock generation circuit, which inputs a horizontal synchronizing signal BD for synchronizing in the main scanning direction, and a clock signal VCK as a clock signal synchronized with the signal.
To occur. The serial signal VDOM is the clock VCK.
Are sequentially transmitted in synchronism with. In addition, the clock signal VCK
Is a processing circuit 43 for processing dot data from the matrix memory.
It is used as a synchronous clock when taking in.

Now, when the image signal VDO of 300 dpi is transmitted from the printer controller to the circuit shown in FIG. 5 in synchronization with the image clock signal VCLK, the image data is sequentially stored in the line memories 25 to 33 and at the same time. , Line memories 25-3 in shift registers 34-42
The matrix information of 11 pixels in the main scanning × 9 pixels in the sub-scanning is extracted from the image data stored in 3. Then, the processing circuit 43 detects the characteristic of the matrix information and compares it with the matrix information of the characteristic image prepared in advance according to the detected characteristic.

Therefore, the color laser beam printer of this embodiment is provided with a line memory for storing image data of 9 lines, and a matrix of 11 pixels × 9 pixels is formed from the line memory when external image data is input. The image data is taken out, and it is sequentially checked whether or not it matches the matrix information of the characteristic image prepared in advance. This characteristic image prepared in advance is not an image that represents the entire bill or securities, but a relatively small and characteristic part of the bill, for example, a portion that represents the amount of bills, a portion that represents an authentication seal, issuance. An image such as a portion representing a person, or a more characteristic portion of these partial images (for example, an edge portion of a character having a certain characteristic font) is considered. In this embodiment, the characteristic image is not stored in the memory as in the conventional color copying machine, but the characteristic image is expressed by a logic circuit.

Next, referring to FIGS. 7 to 8, the main scanning direction 1
A method for extracting the features of the image pattern from the matrix region of 1 pixel × 9 pixels in the sub-scanning direction over the entire region and checking whether or not the image pattern is one for which the specific image is to be recognized will be described.

FIG. 7A is a diagram showing a reference area of 11 pixels in the main scanning direction × 9 pixels in the sub-scanning direction. In FIG. 7A, in order to specify each pixel, a, b,
c, d, e, f, g, h, i, j, k, and the sub-scanning directions are numbered 1, 2, 3, 4, 5, 6, 7, 8, and 9,
Each of the 99 pixels is represented by a combination matrix of the two codes. For example, the central pixel is represented by 5f. In this embodiment, the central pixel is selected as the center of the area where the specific image is recognized.

FIG. 7B shows the reference area of FIG.
1 to X8, Y1 to Y8, 5f divided into 17 small areas,
It shows which pixel each of the small regions is composed of.

Here, the small area X1 is 3d, 3e, 3f, 4d, 4
From the pixels of e and 4f, the small area X2 is 3f, 3g, 3h, 4f, 4g and 4
From the pixel of h, the small area X3 is from the pixels of 6d, 6e, 6f, 7d, 7e, and 7f, the small area X4 is from the pixels of 6f, 6g, 6h, 7f, 7g, and 7h, and the small area X5 is 3d and 3e. , 4d, 4e, 5d, 5e pixels, the small area X6 is 5d, 5e, 6d, 6e, 7d, 7e pixels,
Small area X7 is 3g, 3h, 4g, 4h, 5g, 5h pixels,
The small area X8 is composed of 5g, 5h, 6g, 6h, 7g and 7h pixels.

The small area Y1 includes 1a, 1b, 1c, 2a, 2b,
From the pixels of 2c, 3a, 3b, 3c, the small area Y2 is 1d, 1e, 1f,
From the pixels of 1g, 1h, 2d, 2e, 2f, 2g, 2h, the small area Y3 is
From the pixels of 1i, 1j, 1k, 2i, 2j, 2k, 3i, 3j, 3k, the small area Y4 is from the pixels of 4i, 4j, 4k, 5i, 5j, 5k, 6i, 6j, 6k, and the small area Y5 is 7i, 7j, 7k, 8i, 8j, 8k, 9i, 9j, 9k
From the pixels of, the small area Y6 is 8d, 8e, 8f, 8g, 8h, 9d, 9
From the pixels of e, 9f, 9g and 9h, the small area Y7 is 7a, 7b, 7c and 8
From pixels of a, 8b, 8c, 9a, 9b, 9c, and small area Y
8 is composed of pixels 4a, 4b, 4c, 5a, 5b, 5c, 6a, 6b and 6c. As described above, the reference area includes eight small areas (X1 to X8) each composed of 6 pixels and six small areas each composed of 9 pixels.
Small areas (Y1, Y3, Y4, Y5, Y7, Y8)
Then, it is divided into two small regions (Y2, Y6) each consisting of 10 pixels and a central pixel 5f. When viewed together, it can be seen that there are four types 71 to 74 as shown in FIG. 8 in the small area.

In this embodiment, the characteristics of each small area are parameterized (hereinafter referred to as a characteristic parameter (F)) and quantitatively expressed. Since the F value is obtained for each small area, the characteristic parameter for a specific small area is described as F (Xn) or F (Yn). Further, the characteristic relating to the central pixel 5f is described as F (5f).

The characteristic image prepared in advance and 11 pixels × 9
For comparison with image data of a matrix composed of pixels (hereinafter simply referred to as an input image), first, the overall image is roughly examined, and then the image of the input matrix is compared with which one of the small areas. The similarity is investigated in detail.

The parameter F value indicating the characteristic of each small area (hereinafter referred to simply as the characteristic of the input image) is detected by the circuits shown in FIGS. These circuits include
Binarized image data associated with the pixels shown in FIG. 10 is input. 9 to 10, A1 to A16
Is an exclusive logic (XOR) circuit, and XOR circuits A1 to
A16 takes an exclusive logic for all pixel signals in each small area (when all the input signals are the same, the output is "0", and when even one input signal is different, the output is "1"). . In this way, F (Xn) or F (Yn) is obtained as the characteristic of each small area. For example, when all the pixels in the small area X1 are “0” or “1”, the characteristic of the small area X1 is F (X1) = 0, while any of the pixels in the small area X1 is When it is “1”, the feature of the small area X1 is F
(X1) = 1.

FIG. 11 is a block diagram showing a circuit configuration for recognizing a characteristic image. In FIG. 11, F (X1)
~ F (X8), F (Y1) to F (Y8) are shown in Figs.
The data is obtained by the circuit shown in. Further, 50 is a data matching unit, 51 is a data memory, and 52 is a specific image recognition unit.

First, the characteristics of the input image are directly input to the AND circuit 101. The AND circuit 102 receives a pattern that is similar to the feature of the input image but slightly different (the inverse of F (X2) is input). Thereafter, up to the AND circuit 103, a pattern which is similar to the feature of the input image but slightly different is input. In this way, the AND circuits 101-10
The feature of the input image and many patterns similar thereto are input to 3. Then, if there are features that are exactly the same as or similar to the features of the input image, the outputs of the AND circuits 101 to 103 will be "1". Furthermore, AN
Since the outputs of the D circuits 101 to 103 are input to the OR circuit Q ₁₀₀ , if one of the outputs of the AND circuits 101 to 103 becomes “1”, the output SS of the OR circuit Q ₁₀₀ will be output.
1 becomes "1". The inputs to the AND circuits 101 to 103 are similar to the features of the input image but slightly
Since constitutes a logic circuit such that different patterns are input, it outputs SS1 of the OR circuit Q ₁₀₀ is "1", wherein similar features are logic circuits of the input image as a whole feature Is meant to be present in the pattern generated by.

In other words, the output SS of the OR circuit Q ₁₀₀
The fact that 1 is “1” means that the overall characteristics of the input image include the characteristics of the image that is the target of forgery prevention.

Now, the binary image data forming the small area X1 is directly input to the AND circuit 111. A pattern of image data similar to the binarized image data forming the small area X1 is input to the AND circuits 111 to 112. If there is a feature that is exactly the same as or similar to the binarized data of the small area X1, then AN
The outputs of the D circuits 111 to 113 are "1". further,
Since the outputs of the AND circuits 111 to 113 are input to the OR circuit Q ₁ , if any one of the outputs of the AND circuits 111 to 113 is “1”, the output S1 of the OR circuit Q ₁ is output.
Becomes "1". In this way, a part of the input image,
That is, with respect to the small area X1, it is checked whether or not a similar feature exists in the pattern generated by the logic circuit (feature of the image for which the forgery action is to be prevented). here,
That the output S1 of the OR circuit Q ₁ is a "1" means that there is a feature of the image to be counterfeiting preventing characteristic small area X1 of the input image.

Thereafter, in the same manner, small areas X2 to X8, Y
For 1 to Y8, it is checked whether or not there is a feature of the image targeted for the counterfeit prevention. As a result, if the characteristics of each image to be counterfeiting preventing small area is detected, the output S1~S16 the OR circuit Q ₁ to Q ₁₆ is "1".

[0050] The output of the OR circuit Q ₁ ~Q ₁₆ S1~S16
Is input as one of the inputs of the AND circuits Q ₁ ^{′ to} Q ₁₆ ^′ . The output SS1 of the OR circuit Q ₁₀₀ is input to the other input. Therefore, the overall characteristics of the input image include the characteristics of the image that is the target of forgery prevention, and
When the feature of the image for which the forgery action is to be prevented is detected in each small area, the output X of the AND circuits Q ₁ ^'to Q ₁₆ ^' is detected.
1'-X8 ', Y1'-Y8' (this is referred to as a comparison result) is "1".

Then, the comparison result, the characteristics of the input image and the output SS1 of the OR circuit Q ₁₀₀ are input to the data matching section 50.

FIG. 12 is a diagram showing the circuit configuration of the data matching section 50 and the internal configuration of the data memory 51. Features of input image (F (X1) to F (X8), F (Y1) to F
(Y8)) is input to one input of each of the XOR circuits Q17 to Q32, and the comparison results (X1 'to X8', Y1 'to
Y8 ') is input to the other inputs of the XOR circuits Q17 to Q32. Then, the outputs of the XOR circuits Q17 to Q32 are input to the tristate buffers BF1 to BF16. The output SS1 of the OR circuit Q ₁₀₀ is the inverter 20.
Reversed by 0, tri-state buffers BF1 to BF
16 control inputs. Therefore, the OR circuit Q
_When the output SS1 of ₁₀₀ is "1", that is, when the overall characteristic of the input image has the characteristic of the image for which the forgery action is to be prevented, the outputs (X1 "to X8" of the tristate buffers BF1 to BF16, Y1 ″ to Y8 ″) are output to the addresses A0 to A15 of the 16-bit data memory 51.

If the processing results up to this point are summarized, if each small region has a certain tint and the features are similar, the value of the recognition result output to the data memory 51 is "0". , Otherwise, it is “1”. When the control inputs of the tri-state buffers BF1 to BF16 are "1", the value output to the data memory 51 is controlled to be "1".

FIG. 13 is a block diagram showing the structure of the specific image recognition section 52. The processing of the specific image recognition unit 52 will be described with reference to the flowchart shown in FIG.

First, in step S51, the data memory 51
Input the recognition result data (P) to. Step S52
Then, the recognition result data (P) is read from the addresses A0 to A15 of the data memory 51 and input to the counter 53, and the number of recognition data having a value of "0" is counted. In step S53, the counted number (N) is input to the selector 54 and compared with a preset number (SN) indicating the probability of a specific image. here,
If N ≧ SN, the output signal SS2 of the selector 54 becomes “1”, and the signal SS2 is input to the counter 55. Then, the process proceeds to step S54, and if the output signal SS2 becomes "1" (enable), the counter 55 counts the number of small regions of the input image satisfying N ≧ SN. On the other hand, if N <SN, the process returns to step S51, and the recognition result regarding the next input image is input to the data memory 51.

In step S55, it is checked whether or not there is a new input image. If there is a new input image, the process returns to step S51. If there is no new input image, the process proceeds to step S56. In step S56, the distribution of the counted total number of small areas is checked to determine whether or not the input image includes a specific image that is a target of counterfeiting. That is, the two-dimensional distribution of the number and the number distribution of the counted small regions in the entire region of the input image is checked, and in step S57,
Whether or not a specific image exists is determined. Here, when the probability of being a specific image is high (when the two-dimensional distribution is similar to the distribution of the specific image), the process proceeds to step S58, and the flag of the specific image information section (not shown) is turned on. To do. On the other hand, if it is determined that the probability of being a specific image is low, the processing ends.

The above processing is performed for each color component, and the presence or absence of a specific image is finally determined by the total number of flags of the specific image information section for each color.

The determination of this specific image is performed at least by the print output step of the final color (the last color of the series of print steps), and the final color (for example, Bk (black Toner)) is uniformly output in such a manner that overlapping halftone (gray-tone) images are output so that the recognized specific image is not used as an output image.

However, if it is determined that the image is the specific image after the end of the print process of the final color, all the print outputs have been completed because the print process is being executed by the sequential processing, so that it is performed again. The printing operation of the final color is performed and the halftone image output processing is performed so that the specific image is not output as it is, as described above.

Therefore, according to the present embodiment, the input color image data is stored in the line memory for 9 lines, and the input image data is targeted for the counterfeiting action in units of 11 pixels × 9 lines when the image data is input. It is possible to determine whether or not the input image includes a forgery prevention target image before the printing process for all color components is finally completed. . Further, in the embodiment, when the image data is input in units of 9 lines, the procedure of storing the specific image in the storage medium and comparing after inputting the entire image data is not taken. A logic circuit determines at a high speed whether or not an image subject to anti-counterfeiting has a characteristic, so there is no need for a frame memory to store the entire image data, and there is no adverse effect on printing performance. There is an advantage.

In the present embodiment, no particular reference was made to specifying the position of the image for the purpose of recognizing the image for which the forgery action is to be prevented, but if the device is equipped with a bitmap memory, for example, in FIG. When one pattern of the specific image matches the input image in the bitmap as shown, the count number of the signal in the main scanning direction and the signal in the sub scanning direction corresponding to the bitmap is used as the coordinate, and this is used as the coordinate data. After storing in the memory and inputting data for each color,
The position of the specific image can be recognized by adding the coordinate data to the recognition result described above.

Although the feature detection of the image for which the forgery action is to be prevented in this embodiment is performed by the logic circuit, the feature can be detected by using a program as long as it does not adversely affect the printing performance. is there.

In this embodiment, a line memory for 9 lines of image data is provided, but the present invention is not limited to this. For example, the image data of each color sent from the external device may be stored in the memory.

Further, in the present embodiment, the feature extraction of the image for which the counterfeiting action is to be performed is performed in the unit of 11 pixels in the main scanning direction × 9 pixels in the sub scanning direction, but the present invention is not limited to this. Of course, sizes other than that unit are also acceptable.

[0065]

Other Embodiments In the above-described embodiments, the data input section of the color laser beam printer is provided with a line memory for 9 lines of image data, and each time the data is input to the line memory, the object is protected against forgery. However, in the present embodiment, the apparatus shown in FIG. 1 is used as a common apparatus, a color image capturing section is provided on the transfer drum 103 of the apparatus, and data captured from the color image capturing section is provided. A case of detecting an image that is a target of forgery prevention will be described based on.

FIG. 16 is a diagram showing a state in which a color image capturing section 150 is provided in the apparatus shown in FIG. In FIG. 16, 151 is a specific image recognition part. The color image capturing unit 150 irradiates the paper 102 on which the image is transferred on the transfer drum 103 by the photosensitive drum 100 and the developing device selection mechanism unit 108 with infrared rays and captures the reflected light as tint information of the transferred image. .

FIG. 17 is a block diagram showing the arrangement of the color image capturing section 150. FIG. 17A is a sectional view of the color image capturing section 150 taken along the line aa ′ in FIG. In FIG. 17A, the infrared light output from the infrared light emitting unit 200 is reflected by the image transferred onto the paper 102, and the reflected light is condensed by the lens 201 and enters the light receiving unit 202. FIG. 17B shows a line A-
The color image capturing unit 1 is a plane passing through A'and the line BB '.
It is sectional drawing when 50 is cut. As shown in FIG. 17B, the infrared light emitting unit (LED) 200 and the lens 201 are parallel to the rotation axis of the transfer drum 103 (parallel to the scanning direction of laser light, that is, the main scanning direction). 2) a plurality of (m) light-receiving units 20 are arranged in the same number.
Two are provided. In FIG. 17B, the infrared light emitting units (LEDs) 200-1, 200-2,
..., 200-m and the reference numbers. Light receiving section 202
Then, the amount of incident infrared light is measured and the image information of the transferred image is output. This information is a single infrared light emitting unit (LED) 2
It is obtained every 00 and is treated as 12-bit image information (D) per data, and is input to the specific image recognition unit 151. Therefore, m pieces of image information (D) can be obtained per line. This image information is information representing a red tint when the color sensitivity characteristic of the LED is taken into consideration.

FIG. 18 is a diagram showing the relationship between the sheet 102 on the transfer drum on which the image transfer has been performed and the image capturing position of the color image capturing section 150. In FIG. 18, H ₁ , H ₂ , H ₃ , ..., H _m (m: infrared light emitting unit (LE
The number D) indicates the image capturing position of the color image capturing unit 150, and the color image capturing unit 150 reads the image data immediately below it for one line. V ₁ , V ₂ , V ₃ ,
, V _n indicates the reading position of the image data in the sub-scanning direction, and following the reading of the image data at the position in the sub-scanning direction V ₁ , following the rotation of the transfer drum 103 (the direction of the arrow in the figure), The image data at the position in the sub-scanning direction V ₂ is read in. Thereafter, reading of V ₃ , ..., V _n and image data continues. Information for specific image recognition is input by performing such reading over the entire transferred image.

FIG. 19 is a diagram showing a circuit configuration of the specific image recognition section 151. 1 input to the specific image recognition unit 151
Of the 12-bit image information (D) per infrared light emitting unit (LED) 200, if the most significant bit is D ₁₁ and the least significant bit is D ₀ , the upper 8 bits (D _{11 to} D ₄ ) are specified. Used for image recognition. Lower 4 bits (D _{3 to} D ₀ )
Is considered to be a reading error in the color image capturing unit 150, and is used for sequentially adding to the upper bits for correction.

Next, the specific image recognition processing according to the present embodiment will be described with reference to the circuit of the specific image recognition unit 151 shown in FIG. 19 and the flowchart shown in FIG. It should be noted that this processing is executed after the print output using the three toners (cyan (C), magenta (M), and yellow (Y)) is completed.

First, in step S101, one line
Image information (m pieces) from the color image capturing unit 150
input. Input m image information (D₁₁~ D_Four )
Is the image that is the target of forgery prevention in step S102.
Check if image features are detected. Step S1
In the process of 02, m image information (D
₁₁~ D_Four ), It is similar to the tint of the image information.
And the characteristics of the tint of the image that is subject to forgery prevention
Make many patterns that are thought to have
This is performed by comparing the logic with logic circuits.

Obtained from infrared light emitting unit (LED) 200-1
Image information (D₁₁~ D_Four ), One of the information
By reversing the values of the bits in the section, the color and
Create 16 similar patterns and input them to the AND circuit
And if all the values of that pattern match
Find out. For example, the AND circuit B in FIG.₁ In the
To D₇ ~ D_Five The pattern in which the value of
B₂ Has a bit D_8,D_6,D_Five The putter that reversed the value of
And AND circuit B₁₆Has a bit D _8,D_7,D
_Five The pattern in which the value of is reversed is input. Where
The part of the image that is subject to the forgery prevention against the applied pattern
If there is a pattern that resembles a partial color tone, AND circuit B_1,B
₂,…, B₁₆At least one output of is "1",
This is the OR circuit P₁ Entered in. As a result, the OR circuit
P₁ Output is "1". In this case, the process is
It proceeds to S103.

In step S103, the 16-bit counter 152 outputs the output of the OR circuit P ₁ to the input terminal CIN.
From the output bits QP (MSB) to QA (LSB), and the result is output from the output bits QP (MSB) to QA (LSB). When the count number exceeds a predetermined value, the output of the AND circuit Q1 becomes "1". The output of the AND circuit Q1 is input to the flip-flop circuit 154 and output as the f ₁ signal at the supplied clock (CLK) timing.

By such processing, the infrared light emitting unit (L
ED) image information (D _{11 to} D ₄ ) obtained from 200-1
With regard to (2), if the tint expressed by the image information matches the image for which the forgery action is to be prevented, the output signal f ₁ of the flip-flop circuit 154 becomes “1”.

In the circuit diagram of FIG. 19, the infrared light emitting portion (LE
D) AND circuits B _m , B _{m + 1} , ..., Which are logic circuits related to image information (D _{11 to} D ₄ ) obtained from 200-m
B _{m + 16} , OR circuit P _m , 16-bit counter 153, A
Although only the ND circuit Q _m , the flip-flop circuit 155 and the output signal f _m thereof are shown, the same processing is executed for the image information obtained from the infrared light emitting units (LEDs) 200-2, ..., 200-m. To do.

As a result, if the output signals f _{1 to} f _{m of} the flip-flop circuits are all "1" for the image information for one line, the process proceeds to step S104.
The output FOUT1 is set to "1" by the ND circuit R1. The state of FOUT1 = "1" indicates that the image information for one line obtained from the color image capturing unit 150 has the characteristics of the image for which the forgery action is to be prevented.

After the processing step S104, or if it is determined in the comparison in step S102 that the input image information for one line does not have the characteristics of the image for which the forgery action is to be prevented, the processing is Step S105
Go to and check if there is more image information to enter. Here, if there is image information to be input, the process returns to step S101, the next image information is input from the color image capturing unit 150, and the process is repeated. On the other hand, if it is determined that there is no more image information to input, the process ends.

In this way, it is detected whether or not the image transferred to the paper 102 of the transfer drum 103 (the image transferred by the YMC toner and immediately before fixing) has the characteristics of the image for which the forgery action is to be prevented.

Finally, the output FOUT1 of the AND circuit R1
Is detected to be “1”, the last Bk
Bk during print output operation with (black) toner
The print operation is performed with a uniform density over the entire surface of the image using the (black) toner.

Therefore, according to the present embodiment, it is possible to detect the characteristic of the image for which the forgery action is to be prevented from the actual image immediately before the fixing and prevent the forgery action. Further, in the case of the present embodiment, since the characteristic of the image for which the forgery action is to be prevented is detected at the end of the printing process, the detection of the forgery action is not affected by various color conversions performed inside the apparatus or the color expression of the input image. There are advantages.

In this embodiment, the case where the specific image which is the target of the forgery prevention is detected after the printing operation with the three color toners (C, M, Y) is described, but the present invention is not limited to this. It is not something that will be done. For example, as shown in the flowchart of FIG. 21, the specific image may be detected each time a printing operation using each color toner is performed.

When the processing shown in FIG. 21 is executed, the color image capturing section 150 stores the toner colors (C, M,
An LED that emits light in the optimum wavelength band for Y) is used as a light emitting unit, and the LED is switched according to the printing operation by each toner (C, M, Y).
This point will be described with reference to the flowchart in FIG. In this flowchart, the same processing steps as those already described with reference to FIG. 20 are designated by the same processing step reference numbers, and description thereof will be omitted here.

First, in step S201, what toner is used in the printing operation to be executed is checked. Then, in step S202, the LED used in the color image capturing unit 150 is switched according to the toner color. Less than,
The processing of steps S101 to S105 is performed, and step S
At 203, it is checked whether or not the printing operation using the three toners (C, M, Y) is completed. Here, if the print operation is not completed, the process proceeds to step S20.
Although the process returns to 1, the process ends if it is determined that the print operation has ended.

By carrying out such a processing, it is detected whether or not there is a characteristic of the image for which the forgery action is to be prevented for each toner color. This feature is represented by FOUTM, FOUTC, and FOUTY for each color according to this embodiment.
Finally, comprehensively check the values of FOUTM, FOUTC, and FOUTY, and if all the values are "1", it is determined that the specific image targeted for counterfeiting action is printed,
During the final print output operation with Bk (black) toner, the print operation is performed with a uniform density over the entire surface of the image with Bk (black) toner to prevent the output of a specific image.

In the above two embodiments, 300 dp
Although a color laser beam printer having a resolution of i has been described, the invention is not so limited. For example, 200 dpi, 600 dpi, 1200 d
It goes without saying that the present invention can be applied to color printers having other resolutions such as pi.

Further, in the above two embodiments, the color laser beam printer was used, but the present invention is not limited to this, and is applied to other color printers such as a bubble jet printer and a dot printer. can do.

Furthermore, in the present embodiment, the main scanning direction 11
The feature extraction of the image for which the forgery action is to be prevented was performed in units of pixels × 9 pixels in the sub-scanning direction, but the present invention is not limited to this, and it goes without saying that sizes other than that unit may be used.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0089]

As described above, according to the present invention, when the image data is input, the features of the image represented by the input color image signal are sequentially parameterized, and the parameters and the parameters thus obtained are obtained. Since the characteristics of the predetermined images are compared, and based on the comparison result, it is determined whether the input color image signal includes the characteristics of the predetermined image to recognize the specific image that is the target of forgery prevention. ,
It is not necessary to store the entire input image in any storage medium for image recognition. Therefore, without using a large-capacity storage medium and without degrading printing performance,
For example, a forgery can be prevented by recognizing a specific image representing a bill, a securities, a stamp, or the like.

[0090]

[Brief description of drawings]

FIG. 1 is a side sectional view showing a configuration of a color laser beam printer which is a typical embodiment of the present invention.

FIG. 2 is a diagram showing a part of a pattern represented by dot data.

FIG. 3 is a diagram showing an image data region used as a reference region from the dot pattern of FIG.

FIG. 4 is a diagram showing a reference area constituted by 11 pixels × 9 pixels.

FIG. 5 is a block diagram showing an overall configuration of a circuit for recognizing a specific image.

FIG. 6 is a diagram showing a density distribution of a certain color component of a multivalued color image represented by 256 gradations of 0 to 255.

FIG. 7 is a diagram showing a reference area of 11 pixels in the main scanning direction × 9 pixels in the sub scanning direction and a state in which the reference area is divided into 17 small areas.

FIG. 8 is a diagram showing types of small areas shown in FIG.

FIG. 9 is a diagram showing a detection circuit of a parameter F value indicating the characteristics of each small area.

FIG. 10 is a diagram showing a detection circuit of a parameter F value indicating the characteristics of each small area.

FIG. 11 is a block diagram showing a circuit configuration for recognizing a characteristic image.

12 is a diagram showing a circuit configuration of a data matching section 50 and an internal configuration of a data memory 51. FIG.

FIG. 13 is a block diagram showing a configuration of a specific image recognition unit 52.

FIG. 14 is a flowchart showing a process of a specific image recognition unit 52.

FIG. 15 is a diagram showing a bitmap for specifying the position of a characteristic image.

16 is a diagram showing a color image capturing unit 1 in the apparatus shown in FIG.
It is a figure which shows the mode that 50 was provided.

17 is a block diagram showing a configuration of a color image capturing section 150. FIG.

FIG. 18 is a diagram showing a relationship between a sheet 102 on a transfer drum, on which an image is transferred, and an image capturing position of a color image capturing section 150.

19 is a diagram showing a circuit configuration of a specific image recognition section 151. FIG.

FIG. 20 is a flowchart showing a specific image recognition process according to another embodiment.

FIG. 21 is a flowchart showing a process of recognizing a specific image for each printing operation using each color toner.

[Explanation of symbols]

25-33 line memory 34-42 shift register 50 Data matching circuit 51 data memory 52 Specific image recognition unit 100 photosensitive drum 101 paper feed unit 103 transfer drum 104 fixing device 105 paper output section 111 charger 112 cleaner 150 color image capture unit 151 Specific image recognition unit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/525 B41J 29/38

Claims (5)

(57) [Claims] 1. A color printer device for receiving a color image signal from an external device to form a color image and outputting the color image, wherein the color image signal is input and a quantity formed by a matrix of a predetermined number of pixels is buffered. An input buffer means, and a parameterization means for dividing the color image signal of the matrix of a predetermined number of pixels buffered by the buffer means into a plurality of small areas, and parameterizing image characteristics for each of the divided small areas. , A comparison means for comparing the characteristics of the image of each small area parameterized by the parameterizing means with the characteristics of the predetermined image of the parameterized anti-counterfeiting object, and the comparison result for each small area by the comparing means. Based on the number of small areas including the characteristics of the predetermined image and its distribution, the input color image signal is the predetermined image. And a deterring unit for deterring the color image formed by the input color image signal from being output as it is, based on a discrimination result by the discriminating unit. The parameterization means has a binarization means for binarizing the color image signal for parameterizing the image feature represented by the color image signal, and the parameter of the image feature by the parameterization means. The color printer device, wherein the conversion, the comparison by the comparison unit, and the determination by the determination unit are sequentially performed when a color image signal is input to the input buffer unit. 2. The color printer apparatus according to claim 1, wherein the features of the predetermined image include features of banknotes, securities, and checks. 3. The color printer device according to claim 1, wherein the characteristic of the parameterized predetermined image is represented by a logic circuit. 4. The suppressing means has output means for superimposing and outputting an image having a predetermined color and a uniform density value on the color image transferred to the recording medium. The color printer device according to claim 1, wherein: 5. A color image processing method for detecting a feature of an image using a program to prevent counterfeiting, wherein a color image signal is input and an amount formed by a matrix of a predetermined number of pixels is buffered. A buffering step, a parameterizing step of dividing the buffered color image signal of a matrix of a predetermined number of pixels into a plurality of small areas, and parameterizing image characteristics for each of the divided small areas, Whether the parameterized image feature of each small area is compared with the parameterized predetermined feature of the forgery prevention target image, and whether or not the featured image of the predetermined image is included based on the comparison result for each small area And a comparison step for determining whether or not the input color image signal is based on the number and distribution of the small areas determined to include the features of the specific image. A determination step of determining whether the image is an image, and a suppression step of suppressing the color image formed by the input color image signal from being output as it is, based on the determination result, the parameter A color image processing method, wherein the parameterization of image features in the conversion step and the comparison and determination in the comparison step are sequentially performed when a color image signal is input in the buffer step.