JPH1169142A - Image processor and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor capable of reproducing an original image excellently and adding a prescribed image to the original image inconspicuously and to provide a image processing method. SOLUTION: In the case the color of recording paper is white, only when image data by nine pixels of the original image given from a shift register 501 to a pattern comparator circuit 502 satisfy the density of 00H (white) except the rightmost pixel to add a prescribed image pattern in the vicinity of a contour of the printed image, a forgery prevention logic circuit 503 adds the prescribed image pattern to only part where a density denoted by the image data of the original image is 00H (white).

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 and an image processing method, for example, to an image processing apparatus and an image processing method for adding predetermined image data to input image data.

[0002]

2. Description of the Related Art In recent years, as a device for outputting document or image data generated by an information processing device such as a host computer, an image processing device using an electrophotographic method such as a laser beam printer has been widely used. I have. These image processing apparatuses have many advantages such as high-quality image reproducibility, quietness during printing, and high speed, and are factors that rapidly expand the field of so-called desktop publishing (DTP). ing.

Also, an electrophotographic color laser beam printer has been developed, and a conventional monochrome printing has been developed by improving the performance of a host computer and a controller for generating an image in the color printer. Not only that, printing of full-color images can be easily performed, and it is becoming popular.

However, as color printers capable of high-quality printing as described above have become widespread, countermeasures for preventing forgery of banknotes and securities using such color printers, or counterfeit banknotes and the like have been developed. There is a need for measures to make it easier to track which device was forged when found.

[0005]

Conventionally, in order to track which device the forgery was performed, for example, the device number of the device is determined by the naked eye in light yellow or the like on the entire recording paper at the time of printing. A predetermined pattern which made the processing difficult was formed. However, when a pattern is added in this way, if the image to be printed includes a light-colored image, the color when the image is printed on recording paper changes under the influence of a predetermined pattern. Problem.

When a predetermined pattern is printed on one side of an image printed on a recording sheet, the predetermined pattern may be discriminated instead.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing apparatus and an image processing method for reproducing an original image satisfactorily and adding a predetermined image to the original image so as to be inconspicuous.

[0008]

To achieve the above object, an image processing apparatus according to the present invention has the following configuration.

That is, comparing means for comparing the density pattern of successive pixels represented by input image data with a predetermined density pattern, and when the two density patterns match as a result of the comparison by the comparing means, An adding unit for adding predetermined image data to the image data of the continuous pixels.

Also, for example, the predetermined density pattern is
Except for the density value corresponding to at least the first or last pixel, the other values are predetermined values.

Also, for example, the input image data is image data of a color component of an original image to be reproduced,
The predetermined value is a density value for reproducing a color of a recording medium for reproducing the image data.

Alternatively, in order to achieve the above object, an image processing method according to the present invention has the following configuration.

That is, a comparing step of comparing a density pattern of successive pixels represented by input image data with a predetermined density pattern, and as a result of the comparison in the comparing step, when the two density patterns match. And an adding step of adding predetermined image data to the image data of the continuous pixels.

Further, for example, the predetermined density pattern is:
Except for the density value corresponding to at least the first or last pixel, the remaining values are set to predetermined values.

For example, the input image data is image data of a color component of an original image to be reproduced,
The predetermined value is a density value for reproducing a color of a recording medium for reproducing the image data.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings as an embodiment applied to a color laser beam printer as a typical image processing apparatus.

FIG. 1 is a schematic diagram showing the configuration of a printing system as one embodiment of the present invention. As shown in the figure, the color laser beam printer 501 is connected to a host computer 502 as an external device, and the host computer 502 sends code data and image data described in a printer language to the color laser beam printer 501. Send.

The color laser beam printer 501, based on the received data, has one page of magenta (M),
A video controller 200 for generating cyan (C), yellow (Y), and black (Bk) multi-valued image data;
The video controller (hereinafter, controller) 200
And a printer engine (hereinafter, engine) 100 for printing an image on recording paper in accordance with the multi-valued image data output by the printer. The controller 200 and the engine 100 are connected by an interface signal line 300. In this embodiment, the color laser beam printer 501 is 600 dpi, and the engine 100 is 300 dpi.
It has a resolution of dpi.

FIG. 2 is a block diagram of a video controller 200 according to an embodiment of the present invention.

In the figure, reference numeral 201 denotes a communication interface with a host computer, and a host computer 502
And receives code data and image data described in the printer language, which represent the original image. Reference numeral 202 denotes a CPU that controls the entire controller 200. A ROM 203 stores a control program for the CPU 202, font data, and the like.
Reference numeral 204 denotes a RAM serving as a work area of the CPU 202. A compression / expansion circuit 206 has a function of compressing / expanding RGB 8-bit multi-valued image data. 20
A page memory 5 stores one page of RGB multi-valued image data compressed by the compression / expansion circuit 206.

Reference numeral 207 denotes an image processing unit which converts the RGB multi-valued image data expanded by the compression / expansion circuit 206 into M-, C-, Y-, and Bk plane-sequential multi-valued image data of the printing toner colors of the engine 100. (Color component image data) is subjected to color conversion, and a predetermined pattern (hereinafter, a predetermined pattern) is added to the multi-valued image data for pursuing the counterfeiting of bills and securities by the color laser beam printer 501. And outputs it (details will be described later).

Reference numeral 208 denotes a printer interface, which is an interface circuit with the engine 100. 2
09, the operator operates the color laser beam printer 50;
1 is an operation panel for inputting various settings.

The data between the blocks in the controller 200 is transmitted via the data bus 210.

In the controller 200, the code data input to the communication interface 201 is expanded by the CPU 202 into 300 dpi RGB multi-valued image data (8-bit data for each color) of a character, a figure, or an image according to a predetermined drawing algorithm. Is done. And
The decompressed RGB image data is supplied to a compression / decompression circuit 206.
Compressed. The compressed image data is stored in the page memory 205. This compression / expansion circuit 206
Is, for example, JPEG (Joint Photographic Experts Gr
oup) The input image data is compressed according to the algorithm, and during the printing operation, the compressed data can be output while being expanded in real time.

Next, the controller 200 and the engine 100 shown in FIG.
An interface signal between the two will be described.

The / PRNT signal is a signal sent from the controller 200 to the engine 100, and is a signal for instructing the start of the printing operation or the continuation of the printing operation.

The / RDY signal is a signal sent from the engine 100 to the controller 200, and is set to a state in which the printing operation can be started or a state in which the printing operation can be continued whenever the engine 100 receives the / PRNT signal. It is a signal indicating that there is.

The / TOP signal is a synchronization signal in the sub-scanning (vertical scanning) direction.
Sent from 00.

The / LSYNC signal is used for main scanning (horizontal scanning).
This is a direction synchronization signal, which is sent from the controller 200 to the engine 100.

The signals / VDO7 to / VDO0 are image signals sent from the controller 200 to the engine 100 and indicate multi-valued image data (density information) to be printed by the engine 100. The multi-valued image data is 8-bit data, with / VDO7 at the top and / VDO0 at the bottom. The engine 100 operates from / VDO7 to / VD
When the signal up to O0 is 00H (H represents a hexadecimal number), printing is performed at the maximum density according to the toner color under development, and FFH
Do not print when.

The / IMCHR signal is a signal indicating an image attribute, and is sent from the controller 200 to the engine 100. For example, when this signal is “true (T)”,
It indicates that the image emphasizes the gradation, and when this signal is “false (F)”, it indicates that the image emphasizes the resolution. In the engine 100, when this signal is “true”, the number of lines of PWM (pulse width modulation) processing (hereinafter, in this embodiment, the number of lines is used as a unit representing density) is 100 lines / inch. (Hereinafter, "/ inch" is omitted) and printing is performed, and this signal is "false".
In this case, printing is performed with the PWM line number set to 300 lines.

The VCLK signal is the image signal / VDO7- /
VDO0 and the transfer clock signal of the image attribute signal / IMCHR.
Sent to 0. The controller 200 outputs / VDO7 to / VDO0 in synchronization with the rising edge of the VCLK signal.
And / IMCHR signal.

In the controller 200, / LSY from the engine 100 is output as the horizontal synchronizing signal / LSYNCB.
The NC signal is used.

When one page of the compressed image data is ready in the page memory 205, the controller 200
If the / RDY signal from the engine 100 is "true",
The / PRNT signal is set to “true” to instruct the engine 100 to start the printing process.

<Color Image Forming Process> Next, the process of forming a color image in the printer engine 100 will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 3 is a side view showing the outline of the structure of the printer engine as one embodiment of the present invention. Also,
FIG. 4 is a diagram illustrating the flow of an image signal of the printer engine as one embodiment of the present invention.

3 and 4, the engine 100
Receives the / PRNT signal, the photosensitive drum 106 and the transfer drum 108 are rotated in a direction indicated by an arrow in FIG. 3 (counterclockwise) by a driving unit (not shown). Subsequently, charging of the roller charger 109 is started, and the potential on the photosensitive drum 106 is charged substantially uniformly to a predetermined value. Next, feed roller 1
11, the recording paper 128 is stored in the recording paper cassette 110.
Is supplied to the transfer drum 108.

The transfer drum 108 is formed by stretching a dielectric sheet on a hollow support, and rotates at the same speed as the photosensitive drum 106 in the direction of the arrow (clockwise) in FIG. And). When the recording paper 128 is supplied to the transfer drum 108, the recording paper 128 is held by a gripper 112 provided on a support of the transfer drum 108, and the recording paper 128 is transferred by a suction roller 113 and a suction charger 114. It is adsorbed on the drum 108.

Then, the electrostatic latent images formed on the photosensitive drums 106 are respectively developed with MCYBk toner.
Developing devices 116M, 116C, 116Y, 116B
The support 115 having k is rotated in the direction of the arrow in FIG. 3 (counterclockwise), and the four developing devices are sequentially opposed to the photosensitive drum 106.

The printer engine 100 detects the leading end of the recording paper 128 adsorbed on the transfer drum 106 by the detector 1.
17 and generates a vertical synchronization signal / TOP at a predetermined timing and sends it to the controller 200.

When the controller 200 receives the first / TOP signal, it starts reading compressed image data stored in the page memory 205. The data to be read is the original 8 bits each of RGB in
Expanded in real time to a total of 24 bits of image data,
It is input to the image processing unit 207.

In the image processing unit 207, a 300 dpi R
The color conversion is performed from the input image data of each GB of 8 bits to the MCYBk plane-sequential color component image data. Since this color conversion process is general, a detailed description is omitted. When the image processing unit 207 generates the frame-sequential color component image data, next, a predetermined pattern is added to the image data, and the image attribute signal / IMCHR is applied to each pixel of the image data. Is generated. The details of the process of adding the predetermined pattern will be described later.

Hereinafter, of the frame sequential color component image data,
M (magenta) component image data as an example
0 will be described.

In the image processing unit 207, magenta image data (300 dpi, 8 bits) as the first print color is generated, and when a predetermined pattern is added, the 300 dpi image data is converted to an image signal / image. VD
The signals are sent to the engine 100 as O7 to / VDO0 together with the image attribute signal / IMCHR in synchronization with the VCLK signal.

/ VD output from controller 200
The signals O7 to / VDO0 and / IMCHR are output from the pulse width modulation circuit 10 in the engine 100 as shown in FIG.
1 and a laser drive signal VDO having a pulse width corresponding to the level of the / VDO7 to / VDO0 signal is generated.
Here, the pulse width modulation circuit 101 will be described with reference to FIG.

FIG. 5 is a block diagram of a pulse width modulation circuit according to an embodiment of the present invention.

In the figure, 129 is a line memory. The line memory 129 is configured in a toggle buffer format, and can write and read simultaneously with independent clocks. Reference numeral 130 denotes a clock generation circuit, which is a pattern clock signal PCLK synchronized with the horizontal synchronization signal / HSYNC.
Signal 1 / 3PC obtained by dividing PCLK by 1/3
Generate LK. The clock signal PCLK is 300 dp
The period for printing one dot with i is one cycle.

Further, 131 is a gamma conversion circuit, 132 is a digital / analog (D / A) conversion circuit, 133 is a phase control circuit, 134 and 135 are triangular wave generation circuits, 136 and 137 are comparators, 138 is a selector, and 1
39 is a D flip-flop.

Next, the operation of the pulse width modulation circuit 101 having the above configuration will be described. First, the / VDO7 to / VDO0 signals and the / IMCHR signal for one main scanning line are written to the line memory 129 as magenta image data for one main scanning line in accordance with the clock signal VCLK. When the writing of the first line is completed, the line memory 1 is output by the horizontal synchronization signal / HSYNC of the next line.
The bank for writing 29 is switched, and writing of the signal of the next second line is performed. At this time, / VDO of the first line previously written in the line memory 129 is used.
7 to / VDO0 signal and / IMCHR signal are read out according to the pattern clock signal PCLK and input to the γ correction circuit 131.

In the γ correction circuit 131, / VDO7 to / VDO7
For the DO0 signal, γ conversion optimal for the process conditions of the engine 100 is performed according to the number of lines of PWM specified by the / IMCHR signal. The image signals / VD7 to / VDO as 8-bit multivalued image data subjected to γ conversion are
The value is converted into an analog voltage by the D / A conversion circuit 132 according to the value, and becomes an analog video signal AVD. At this time, the D / A conversion circuit 132 outputs the image signal / VD7 to / VD7.
The minimum voltage is generated when the value of DO is 00H, and the maximum voltage is generated when the value of DO is FFH. And the analog video signal AVD is
It is input to the negative inputs of comparators 136 and 137.

The outputs TRI1 of the triangular wave generating circuit 134 and the output TRI2 of the triangular wave generating circuit 135 are input to the positive inputs of the comparators 136 and 137, respectively. The triangular wave generating circuit 134 is configured, for example, as shown in FIG.

FIG. 6 is a configuration diagram of a triangular wave generation circuit as one embodiment of the present invention. In the figure, a changeover switch 152 includes a clock signal PCL obtained by changing the phase of the pattern clock signal PCLK by a phase control circuit 133.
K 'has been entered. The switch 152 controls the clock P
When CLK 'is at the H level, the terminal a is connected to the terminal c, and the current I from the current source 150 flows through the capacitor 153. As a result, the capacitor 153 is charged with electric charge, and the voltage value V increases linearly. Next, the clock P
When CLK 'goes low, the b terminal and the c terminal of the switch 152 are connected, the current I flows through the current source 151, the electric charge stored in the capacitor 153 is discharged, and the voltage value V decreases linearly. PC as above
A triangular wave signal TRI1 having a period equal to LK is obtained.

The triangular wave generating circuit 135 is basically the same in configuration as the triangular wave generating circuit 134, and will not be described in detail. However, since the input clock is ３ PCLK ′, the output of the triangular wave signal TRI2 is The cycle is 1 / 3PC
LK, ie, three times TRI1.

Next, the comparators 136 and 137 compare the voltage level of the analog video signal AVD with the voltage levels of the triangular wave signals TRI1 and TRI2.
Pulse width modulation signals PWM1 and PWM2 are obtained, respectively. Therefore, the number of lines of the pulse width modulation signal PWM1 is 300
The number of lines of the line and pulse width modulation signal PWM2 is 100 lines.

Then, the pulse width modulation signals PWM1 and P
WM2 is input to the selector 138, and the image attribute signal /
Selected according to IMCHR. Specifically, / IMC
When HR is “true”, that is, at L level, PWM2 excellent in gradation is selected. Also, when / IMCHR is “false”, that is, when it is at the H level, PWM having excellent resolution is used.
1 is selected.

The signal selected by the selector 138 is sent to the laser driver 102 as a laser drive signal VDO. At the time of development described later, the laser drive signal V
The density of the image to be printed is reproduced according to the pulse width of the DO. FIG. 7 shows a timing chart of the pulse width modulation circuit 101 described above.

Next, referring to FIG.
2 drives the laser diode 103 according to the laser drive signal VDO. A laser beam 127 emitted from the laser diode 103 is deflected by a rotary polygon mirror 104 that is rotationally driven in the direction of an arrow by a motor (not shown), passes through an imaging lens 105 disposed on an optical path, and In the main scanning direction. Photosensitive drum 1
In step 06, a latent image corresponding to the laser beam 127 is formed on the photosensitive drum 106 by being scanned in the main scanning direction by the laser beam 127. At this time, the beam detector 107 detects the scanning start point of the laser beam, and based on this detection signal, is a horizontal synchronization signal / LSYN for determining the image writing timing in the main scanning direction.
A C signal is generated. Further, since the photosensitive drum 106 is rotating as shown in FIG. 3 as described above, the above-described operation in the main scanning direction is repeated, so that a magenta latent image for one page is formed on the photosensitive drum 106. Is formed.

When the phase of the pattern clock signal PCLK is the same in each main scan, the formed image is connected in the vertical direction (sub-scan direction), and particularly, the number of lines of PWM is 2
In the case of the 00 line, there is a possibility that after printing, vertical streaks will appear on the recording paper and become conspicuous. Therefore, in this embodiment,
The phase control circuit 133 in FIG. 5 shifts the phase of the pattern clock signal PCLK for each main scan within the range of one clock cycle, thereby preventing the generation of vertical streaks.

Here, returning to FIG. The latent image formed on the photosensitive drum 106 is developed by the developing device 116M containing magenta toner, and becomes a magenta toner image. The magenta toner image is transferred by the transfer charger 119 onto the recording paper 128 that is attracted to the rotating transfer roller 108. At this time, the toner remaining on the photosensitive drum 106 without being transferred is removed by the cleaning device 125.
Removed by With the above operation, the recording paper 128
A magenta toner image for one page is formed thereon.

Next, the support 115 of the developing device is rotated so that the developing device 116 C containing cyan toner as the second toner is opposed to the photosensitive drum 106. continue,
As in the case of magenta, the leading end of the recording paper 128 rotating while being attracted to the transfer roller 108 is detected by the detector 117, and a vertical synchronizing signal / TOP is generated.
Send to 00. In response, the video controller 20
0 reads out the compressed image data from the page memory 205, decompresses the original RGB and 8-bit image data in real time by the compression / decompression circuit 206, and inputs it to the image processing unit 207. The image processing unit 207 generates the data of cyan as the second print color and the image attribute signal / IMCHR from the RGB, 8-bit input image data. Less than,
By the same operation, the cyan toner image is transferred onto the recording paper 128 so as to overlap the magenta toner image.

Further, similarly, a yellow toner image as the third toner and a black toner image as the fourth toner are transferred onto the recording paper 128 in a superimposed manner, so that a full-color toner image corresponding to the original image is obtained. It is formed.

Recording paper 128 onto which four color toner images have been transferred
Is separated from the transfer drum 108 by a separation claw 121 via a separation charger 120, and is supplied to a fixing device 123 by a conveyance unit 122. At this time, the transfer drum cleaner 126 cleans the surface of the transfer drum.

The toner image on the recording paper is melted and fixed by being heated and pressed by the fixing device 123, and becomes a final color output image. Then, the recording paper on which the recording has been completed is discharged to the paper discharge tray 124.

As described above, in the engine 100, a full-color image is formed by an electrophotographic process.

<Forgery Prevention Processing> Next, the image processing unit 207
Will be described. In this embodiment, in the color laser beam printer 501,
A case in which the color of the recording paper 128 is general white will be described.

FIG. 8 is a block diagram of an image processing section as one embodiment of the present invention. As shown in the drawing, the image processing unit 207 includes a color signal conversion circuit 252 and a forgery prevention processing circuit 253.

The RGB image data from the compression / expansion circuit 206 is input to the color signal conversion circuit 252. The color signal conversion circuit 252 converts the input RGB image data into M,
8-bit image data for each color of C, Y, and Bk / D7 to / D0
Color conversion. This color conversion is performed in the order of M, C, Y, and Bk in synchronization with the / TOP signal.

Subsequently, the converted M, C, Y, Bk image data / D7 to / D0 (300 dpi, 8 bits)
Is input to the forgery prevention processing circuit 253. The forgery prevention processing circuit 253 has a function of adding a predetermined pattern for preventing forgery to the image data input from the color signal conversion circuit 252.

FIG. 9 is a block diagram of a forgery prevention processing circuit according to an embodiment of the present invention.

In the figure, reference numeral 501 denotes 9 in the main scanning direction.
A shift register that stores data for pixels and shifts the data in synchronization with the VCLK signal. 502 includes two comparison circuits 502a and 502b, and AND
This is a pattern comparison circuit including (logical product) elements, and compares image data for nine pixels from the shift register 501 with a predetermined condition. Reference numeral 503 denotes a forgery prevention logic circuit that adds a predetermined pattern to the input image data of nine pixels in accordance with the output signal from the pattern comparison circuit 502 and the VCLK signal.
a, two AND elements, and an OR (logical sum) element. Here, the operation of the pattern comparison circuit 502 is shown in FIG.
This will be described with reference to FIG.

FIG. 10 is a diagram for explaining the operation of the pattern comparison circuit as one embodiment of the present invention. The pattern comparison circuit 502 determines whether all of the nine pixels in the main scanning direction from the shift register 501 are white data (00H), for example, as shown in FIG. Is determined. This is a process for judging whether or not the input image data of nine pixels corresponds to the contour portion of the original image to be reproduced. Therefore, for example, the pattern comparison circuit 502 may determine that a plurality of pixels continuous from the right (or left) end, not the rightmost pixel, are not white data. However, in this case, it is needless to say that the number of pixels to be shifted by the shift register 501 is preferably larger for the purpose of detecting the contour portion of the original image.

When this condition is satisfied, the pat-add signal is asserted from the pattern comparison circuit 502, and a predetermined pattern is added to the original image in the forgery prevention logic circuit 503. That is, the comparison circuit 502a outputs “true” when the density values of the eight pixels from the left are 00H. The comparison circuit 502b outputs "true" when the rightmost one pixel is not 00H. And 2
When the outputs of the two comparison circuits are “true”, the subsequent AND element outputs a pat-add signal.

Pat_a from pattern comparison circuit 502
The output of the dd signal is continued for nine periods of the VCLK signal after it is determined that all of the nine pixels in the main scanning direction except the rightmost one pixel are white data.

Next, the process of adding the original image and the predetermined pattern, which is performed by the forgery prevention logic circuit 503, will be described.

FIG. 11 is a view for explaining an OR operation between image data of an original image and predetermined pattern data according to an embodiment of the present invention.

In the pattern comparison circuit 502, pat
When the _add signal is asserted, a predetermined pattern prepared in advance in the pattern image adding circuit 503a and image data of the original image are OR-operated, and one pixel is synchronized with the VCLK signal, as shown in FIG. It is output while being shifted by minutes. Then, the forgery prevention logic circuit 503
Unless the pat-ad signal is asserted again, the image signals / VDO7 to / VDO0 (30) are added without adding a predetermined pattern to the input image data of the nine pixels of the original image.
(0 dpi, 8 bits).

When the / PRNT signal is output from the controller 200 to the engine 100, in synchronization with the first vertical synchronizing signal / TOP, first, magenta image data / D7-// which is the first color component. D0 is sent to the engine 100 together with the image attribute signal / IMCHR in synchronization with the image clock signal VCLK. That is, in the above configuration, the M, C, Y, and Bk plane-sequential image data / D7 to / D0 developed at 300 dpi are output to the engine 100 in synchronization with the 300 dpi image clock signal VCLK. Become. Here, the flow of the forgery prevention process will be described with reference to FIG.

FIG. 12 is a flowchart showing the forgery prevention processing as one embodiment of the present invention, and shows the flow of the operation of the forgery prevention processing circuit 253. This process is started when the / PRNT signal is output from the controller 200 to the engine 100.

Steps S1 and S2: It is determined whether the vertical synchronization signal / TOP has been detected. If YES, the synchronization signal / LSYNC from the engine 100 in the main scanning direction is determined.
It is determined whether a signal has been detected.

Step S3, Step S5: Step S
In the case of YES in 2, the pattern comparison circuit 502
It is determined whether or not the image data of the original image for 9 pixels and the predetermined image data for comparison match. If the result is NO, the image data of the original image is converted into an image through the forgery prevention logic circuit 503. After conversion into data / D7- / D0, the engine 100
Output to

Step S4: If YES in step S3, the forgery prevention logic circuit 503 adds predetermined pattern data to the image data of the original image, and outputs the image data / D7 to / D7.
After being converted to D0, it is output to engine 100.

Step S6: One line of image data /
It is determined whether D7 to / D0 have been output to engine 100, and if NO, the process returns to step S2 to continue the above processing.

Step S7: In the case of YES in step S6, it is determined whether image data / D7 to / D0 for one page has been output to engine 100, and in the case of NO, the process returns to step S2 to return to the above-described step. Continue processing.

Step S8: If YES in step S7, it is determined whether or not all the image data of the original image to be currently printed has been output to the engine 100. If NO, the process returns to step S1 to return to another page. The above processing is continued for the image data. On the other hand, in the case of YES, the process ends.

<Effects of this Embodiment> As described above, in this embodiment, the color laser beam printer 50 is used.
1, when the color of the recording paper 128 is a general white color, the image data of 9 pixels of the input original image has a density value of 00H (white) except for the rightmost pixel as a predetermined condition. Only when the condition shown in FIG. 10 is satisfied, the density value represented by the image data of the original image is 00.
Only added to the H (white) part. As a result, even when a light-colored original image is printed (reproduced) on a recording sheet, it is possible to prevent the color of the original image from being changed by the influence of the predetermined pattern, and to prevent the outline of the printed image from being changed. A predetermined pattern can be added only in the vicinity of the portion, and printing of the predetermined pattern can be prohibited in a portion where an image is not printed (blank portion). Therefore, the predetermined pattern can be made less noticeable.

In the above embodiment, the recording paper 128
Is described as a general white color, and the density value to be compared is white (00H). However, the present invention is not limited to this case. Needless to say, it is only necessary to change the density value to be compared according to the color of the paper.

In the above-described embodiment, the forgery prevention processing circuit 253 performs the forgery prevention processing with nine pixels as one unit. However, if the idea of “adding a predetermined pattern only in the vicinity of the outline portion” is satisfied, Needless to say, it is not limited to the unit of 9 pixels.

The above-described predetermined pattern is an example, and the predetermined pattern itself may be periodically changed based on predetermined conditions. In the above description, an example in which the same predetermined pattern logic is applied to four image planes of magenta, cyan, yellow, and black has been described.
Since the visual characteristics are different for each color, the predetermined pattern logic may be changed depending on the plane. In that case, a signal indicating the color currently being processed by the controller 200 is sent to the image processing unit 20.
7 to switch the logic. Further, a plurality of conversion logics may be prepared so that they can be selected according to the environment such as the area where the printer is used.

[0089]

[Other Embodiments] The present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and can be applied to a single device (for example, a copying machine). Machine, facsimile machine, etc.).

Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

Examples of the storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, and CD.
-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instructions of the program code. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that a CPU or the like provided in the function expansion board or the function expansion unit performs a part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0095]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and an image processing method for reproducing an original image satisfactorily and adding a predetermined image to the original image so as not to stand out.

[0096]

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a printing system as one embodiment of the present invention.

FIG. 2 is a block diagram of a video controller 200 according to an embodiment of the present invention.

FIG. 3 is a side view showing the outline of the structure of a printer engine as one embodiment of the present invention.

FIG. 4 is a diagram illustrating a flow of an image signal of a printer engine as one embodiment of the present invention.

FIG. 5 is a block diagram of a pulse width modulation circuit as one embodiment of the present invention.

FIG. 6 is a configuration diagram of a triangular wave generation circuit as one embodiment of the present invention.

FIG. 7 is a timing chart in the pulse width modulation circuit as one embodiment of the present invention.

FIG. 8 is a block diagram of an image processing unit as one embodiment of the present invention.

FIG. 9 is a block diagram of a forgery prevention processing circuit as one embodiment of the present invention.

FIG. 10 is a diagram illustrating the operation of the pattern comparison circuit as one embodiment of the present invention.

FIG. 11 is a diagram illustrating an OR operation of image data of an original image and predetermined pattern data according to an embodiment of the present invention.

FIG. 12 is a flowchart showing a forgery prevention process as one embodiment of the present invention.

[Explanation of symbols]

100 printer engine, 101 pulse width modulation circuit, 102 laser driver, 103 laser diode, 104 rotating polygon mirror, 105 imaging lens, 106 photosensitive drum, 107 beam detector, 108 transfer drum, 109 roller charger, 110 recording paper cassette, 111 paper feed roller, 112 gripper, 113 suction roller, 114 suction charger, 115 developing device support, 116M, 116C, 116Y, 116Bk developing device, 117 detector, 119 transfer charger, 120 separation charger, 121 separation claw, 122 conveyance means, 123 fixing device, 124 discharge tray, 125 cleaning device, 126 transfer drum cleaner, 127 laser beam, 128 recording paper, 129 line memory, 130 clock generation circuit, 13 γ conversion circuit, 132 D / A conversion circuit, 133 phase control circuit, 134 triangular wave generation circuit, 135 triangular wave generation circuit, 136 comparator, 137 comparator, 138 selector, 139 D flip-flop, 150 current source, 151 current source, 152 switching Switch, 153 capacitor, 200 video controller, 201 communication interface, 202 CPU, 203 ROM, 204 RAM, 205 page memory, 206 compression / expansion circuit, 207 image processing unit, 208 printer interface, 209 operation panel, 210 data bus, 211 extension ROM, 215 EEPROM, 222 extended RAM, 250 image operation unit, 252 color signal conversion circuit, 253 forgery prevention processing circuit, 300 engine I / F, 501 shift Register, 502 pattern comparison circuit, 502a, 502b comparison circuit, 503 forgery prevention logic circuit, 503a pattern image addition circuit,

Claims (11)

[Claims] 1. A comparing means for comparing a density pattern of a continuous pixel represented by input image data with a predetermined density pattern. When the two density patterns match as a result of the comparison by the comparing means, In the image data of the continuous pixels,
An image processing apparatus comprising: an adding unit that adds predetermined image data. 2. The image processing apparatus according to claim 1, wherein the predetermined density pattern is a predetermined value except for density values corresponding to pixels other than at least one pixel at the beginning or end of the predetermined density pattern. 3. The input image data is image data of a color component of an original image to be reproduced, and the predetermined value is a density value for reproducing a color of a recording medium for reproducing the image data. 3. The image processing apparatus according to claim 2, wherein 4. The image processing apparatus according to claim 1, wherein the adding unit calculates a logical sum of image data of a pixel having a predetermined density value among the plurality of pixels and the predetermined image data.
The image processing apparatus according to any one of the preceding claims. 5. The input image data is M, C,
Recording means for recording the input image data and / or the image data to which the predetermined image data has been added by the adding means on the recording medium, Phase control means for changing the phase of a predetermined clock signal within one cycle of the clock signal; and the image data based on the clock signal controlled by the phase control means. 5. The image processing apparatus according to claim 1, further comprising: a pulse width modulation unit configured to perform pulse width modulation on the added image data. 6. 6. The image processing apparatus according to claim 1, wherein the predetermined image data represents an image pattern for tracking forgery. 7. A comparing step of comparing a density pattern of a continuous pixel represented by input image data with a predetermined density pattern, and as a result of the comparison step, when the two density patterns match. An adding step of adding predetermined image data to the image data of the continuous pixels. 8. The image processing method according to claim 7, wherein the predetermined density pattern has a predetermined value except for a density value corresponding to a pixel other than at least one pixel at the beginning or end of the predetermined density pattern. 9. The input image data is image data of a color component of an original image to be reproduced, and the predetermined value is a density value for reproducing a color of a recording medium for reproducing the image data. 9. The image processing method according to claim 8, wherein: 10. A computer-readable storage medium storing an image processing program for adding predetermined image data to input image data, wherein a density pattern of continuous pixels represented by the input image data is obtained. And a code of a comparing step of comparing with a predetermined density pattern, and when the two density patterns match as a result of the comparison step, adding predetermined image data to the image data of the continuous pixels. And a code for an additional step. 11. The input image data is M,
C, Y, and Bk plane-sequential image data, and further, the input image data and / or the image data to which the predetermined image data has been added in the adding step are recorded on the recording medium. Having the code of the recording process,
The code of the recording step is based on a code of a phase control step of changing a phase of a predetermined clock signal within one cycle of the clock signal, and the clock signal controlled by the phase control step. The storage medium according to claim 10, further comprising: a code of a pulse width modulation step of performing pulse width modulation on the image data and / or the added image data.