JP2001103279A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that can output an image without degrading image quality even when color conversion processing is applied to specific information in the case of copying an image including the specific information that is visibly or invisibly imbedded to substantial image information. SOLUTION: When a user sets color conversion processing (S30), the image forming device discriminates a pixel to configure a trace pattern from an input image (S31, S32), and when the image forming device discriminates that the pixel is a pixel of the trace pattern, no color conversion is applied to the pixel (S33). When the device discriminates that the pixel is not the pixel of the trace pattern, color conversion is applied to the pixel (S35).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for generating input image information and printing out the image information. In particular, in order to enable tracking of an output image, the image information is specified as visible or invisible to original image information. The present invention relates to an image creating apparatus that prints out an image in which information is written.

[0002]

2. Description of the Related Art Along with recent advances in digital signal processing technology, printing apparatuses and copiers for printing and outputting high-quality images have been developed. Copiers and the like that can obtain such high-quality images may be illegally used for the purpose of counterfeiting banknotes and securities.

Conventionally, various techniques for preventing such unauthorized use have been devised. For example, there is a technique in which a tracking pattern, which is information for tracking a situation when the image is copied, is input into an output image. The tracking pattern makes it possible to track the situation such as when and by which machine a copy was made. Information such as the machine name and serial number of the copying machine that copied the image and the date and time of the copy were recorded in a dot in a certain area. It is expressed as a pattern.
In general, tracking patterns need to be printed invisible or invisible, so the colors of the dots that compose them are:
Yellow, which is hard to perceive visually, is selected.

[0004]

Some color copiers capable of copying and outputting a color original have a color conversion function of converting one specified color into another color and outputting the converted color. . In such a copying machine, when the conversion from yellow to another color is set by the user, the color of the tracking pattern hit in the document is converted to another color by copying, and a color that is easily recognized by human eyes. And appears as noise.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to perform color conversion processing on an image containing specific information which is written invisibly or invisibly in original image information. An object of the present invention is to provide an image creating apparatus capable of outputting an image retaining original specific information without deteriorating the image quality.

[0006]

An image forming apparatus according to the present invention is an image forming apparatus for printing out an image in which specific information is written invisibly or hardly visible in image information, and an input means for inputting an image. Printing means for printing the input image, designation means for designating a color conversion process between the input image and the printed image, and color conversion means for transforming the color of the input image based on the designation by the designation means. Detecting means for detecting specific information from the input image; and performing color conversion processing on a portion of the input image where the specific information is detected when the color conversion processing is specified by the specifying means. And control means for controlling the color conversion means so as not to cause the error.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a digital color copying machine as an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In the digital color copying machine of this embodiment, when a color conversion process is set when copying a document having specific information (tracking pattern) written invisibly or hardly visible in the original image information, Then, the printing process is controlled so that the color conversion is not performed on the pixels constituting the specific information. Thus, even when a color conversion process is performed when copying a document on which specific information is written, it is possible to copy the document without deteriorating the image quality and losing the specific information. it can.

FIG. 1 is a sectional view showing the overall configuration of a digital color copying machine according to the present invention. The digital color copying machine is roughly divided into an image reader unit 100 for reading a document image and a copying unit 200 for reproducing an image read by the image reader unit 100.

The configuration of the image reader unit 100 is the same as the conventional one. Here, the scanner 10 includes an exposure lamp 12 for irradiating a document, a rod lens array 13 for condensing light reflected from the document, and a contact-type CCD color image sensor 14 for converting the collected light into an electric signal. ing.
The scanner 10 is driven by a motor 11 at the time of reading a document and moves in the direction of the arrow (sub-scanning direction).
5 scans the original placed thereon. The image of the document surface irradiated by the exposure lamp 12 is photoelectrically converted by the image sensor 14. R, G, obtained by the image sensor 14,
The multi-valued electrical signals of the three colors B are read by the read signal processing unit 20 into yellow (Y), magenta (M), cyan (C),
The data is converted to any of 8-bit grayscale data of black (K) and stored in the synchronization buffer (FIFO) 30.

Next, in the copying section 200, the print head section 31 performs gradation correction (γ correction) on the inputted gradation data in accordance with the gradation characteristics of the photosensitive member,
D / A conversion is performed on the corrected image data to generate a semiconductor laser drive signal, and the semiconductor laser is caused to emit light by the drive signal. The laser beam generated from the print head unit 31 by modulating the light emission intensity in accordance with the gradation data exposes the rotatably driven photosensitive drum 41 via the reflecting mirror 39.

The photosensitive drum 41 is irradiated by an eraser lamp 42 before being exposed for each copy, and is uniformly charged by a charging charger 43. When exposure is performed in this state, an electrostatic latent image of the document is formed on the photosensitive drum 41. Only one of the cyan, magenta, yellow, and black toner developing units 45a to 45d is selected to develop the electrostatic latent image on the photosensitive drum 41.

The developed toner image is transferred to a transfer charger 4
6 is transferred to the copy paper wound on the transfer drum 51. This printing process is repeated for four colors of yellow (Y), magenta (M), cyan (C), and black (K). At this time, the scanner 10 repeats the scanning operation in synchronization with the operations of the photosensitive drum 41 and the transfer drum 51.

Thereafter, the copy paper is separated from the transfer drum 51 by operating the separation claw 47, fixed through a fixing device 48, and discharged to a discharge tray 49.
The copy paper is fed by the paper cassette 50 and the leading end thereof is chucked by the chucking mechanism 52 on the transfer drum 51, so that no positional deviation occurs during transfer.

The digital color copier has an operation panel 16 on which a user makes various settings as shown in FIG.
It has. The operation panel 16 has a display panel section 16a for displaying a setting status, an operation state, and the like, and a plurality of keys such as a start key 16c for starting a copying operation and a ten-key 16h for setting the number of copies and the like. . The user can set various operation modes on the operation panel 16, and can also set a color conversion process for converting a specific color of the document image to create an output image.

(Read Signal Processing) FIG.
0 is a block diagram of FIG. Color CCD image sensor 1
The multi-valued electrical signals of the three colors r, g, and b obtained by (4)
First, after being amplified and optimized in the analog processing unit 320, the A / D conversion unit 321 outputs R, G,
Each of them is converted into a B multi-level digital signal. The digital signal output from the A / D conversion unit 321 is input to the shading correction unit 323 after being converted into serial data by the serial signal conversion processing unit 322.

In the shading correction section 323, RGB
The shading correction is performed based on the digital image data. The CCD image sensor 14 is composed of three lines of CCD sensors arranged at predetermined intervals, and each of the read RGB data has a timing shift.

The data subjected to the shading correction is corrected in the sensor window position correcting section 324 to the synchronized data by correcting the above timing shift. The RGB data subjected to the position correction is output to the reflectance / density conversion unit 325. At this time, the B data is also input to the tracking pattern detection processing unit 329. The tracking pattern detection processing unit 329 detects a tracking pattern that is specific information included in the document image. As described in the related art, the tracking pattern is a pattern in which information for specifying the source of a printed material, such as the machine name and serial number of a copying machine, is configured by dots.

When the tracking pattern is detected, the arrangement data of the tracking pattern is stored in the pattern memory 330, and the data is output to the print head unit 31 described later. The reflectance / density conversion unit 325 converts R, G, and B data, which are reflectance data, into DR, DG, and DB data that is 256 grayscale data.
The DR, DG, and DB data are output to the UCR / PB masking processing unit 326.

The UCR / BP masking processing section 326 converts the DR, DG, and DB data into 256 density gradation data of cyan (C), magenta (M), yellow (Y), and black (K), and then converts the data to black. Processing to remove C, M, and Y data values from a black part (UCR processing) and to add black (K) gradation data (BP processing) in order to improve the reproducibility of Is applied.

Thereafter, a predetermined masking process is performed on the copy paper so as to reproduce the same color as that of the original in consideration of the reading characteristics of the CCD image sensor 14 and the adhesion characteristics of the toner to the copy paper. Outputs color data according to the process. Data of any one of C, M, Y, and Bk output from the UCR / BP masking processing unit 326 is subjected to spatial filter processing such as smoothing and edge enhancement in the MTF correction unit 327.

The magnification change movement processing unit 328 includes the MTF correction unit 32
Using the data from step No. 7, a scaling movement process is executed in accordance with the set copy magnification and the edited contents. The data output from the magnification change processing unit 328 is input to the print head unit 31 via a buffer. Print head 3
1 generates a semiconductor laser drive signal by D / A converting the input gradation data, causes the semiconductor laser to emit light by this drive signal, and exposes the photosensitive drum 41.

The print head unit 31 receives the image data sent from the read signal processing unit 20 and the data of the detected tracking pattern. The printer head unit 31 corrects the value of the driving level based on the value of the driving level of the actual tracking pattern recorded on the document, and drives the tracking pattern into the image data of the document with the corrected value of the driving level. . Thus, the tracking pattern can be driven at an appropriate level.

FIG. 4 is a diagram showing the detailed configuration of the print head unit 31. The image data (8 bits) from the read signal processing unit 20 is passed through an interface unit 451 to a first-in first-out memory (hereinafter, referred to as a “FIFO memory”).
452. The FIFO memory 452 is a line buffer memory capable of storing gradation data of a predetermined number of lines in the main scanning direction, and operates between the image reader unit 100 and the copying unit 200 shown in FIG. It is provided to absorb the difference in clock frequency. F
The data in the IFO memory 452 is input to the tracking pattern generation and addition unit 453.

The tracking pattern generation and addition section 453 adds a tracking pattern of a predetermined driving level sent from the printer control section 401 to the image data. The process of adding a tracking pattern is executed by the printer control unit 401 according to a program stored in the control ROM 402. The layout data of the tracking pattern read from the image data of the document input from the pattern memory 330 of the reading signal processing unit 20 is stored in the reading tracking memory RAM 460 and input to the pattern matching unit 462.

The pattern matching unit 462 reads out the layout data of the tracking pattern meaning the model name and serial number of the copying machine from the tracking information storage ROM 461, and compares it with the layout data of the tracking pattern read from the image data of the document. Perform pattern matching. By this pattern matching, it can be determined whether or not the model that has created the original image is the same as the copying machine.

The print control unit 401 executes the setting process of the yellow dot ejection level, and then outputs the set ejection level value to the tracking pattern generation and addition unit 453.

The gamma correction unit 454 includes a printer control unit 401
Tracking pattern generation and addition unit 4 based on the gamma correction data from
Correct the data from 53. Various gradation correction data (γ table, various correction values, etc.) are stored in the data ROM 403.
Is also stored. The data subjected to the γ correction by the γ correction unit 454 is converted to an analog voltage by the D / A conversion unit 456. This analog voltage is sent to the LD laser driver 457, and causes the laser diode 458 to emit light at the light intensity of that value.

(Process for Determining Arrangement Position of Tracking Pattern) FIG. 5 is a flowchart showing the operation of the printer control unit 401. First, the printer control unit 401
Image data is read out via the memory 452 (S1),
An input is made to a predetermined storage unit (not shown) (S2). Thereafter, color conversion processing of the image is performed based on the setting by the user (S3). Details of this processing will be described later. Thereafter, the image after the color conversion to which the tracking pattern is added is output to the tracking pattern generation and addition unit (S4).

(Color Conversion Processing) FIG. 6 shows a flowchart of the color conversion processing. In the present color conversion processing, color conversion is not performed on the pixels constituting the tracking pattern.

First, it is determined whether or not the user has made a color conversion setting (S30). If the color conversion setting has not been made, the process returns. If the color conversion setting has been made, the following processing is performed while scanning the entire image.

That is, if the color conversion setting has been made, it is determined whether or not the color of one pixel constituting the image is equal to the color yellow constituting the tracking pattern (S31). If the color of the pixel is yellow, it is determined whether or not the size of the pixel is equal to or smaller than a predetermined value (S32). If the size of the pixel is equal to or less than the predetermined value,
The color conversion process is not performed on the pixel (S33), and if the size of the pixel is larger than a predetermined value, the color conversion process is performed on the pixel (S35). That is, here, if the color of the pixel is yellow and the size is equal to or smaller than a predetermined value, the pixel is determined to be a pixel forming the tracking pattern, and is determined to be a pixel forming the tracking pattern. When it is determined, the color conversion process is not performed. Thereafter, it is determined whether or not the above processing has been performed for all the pixels in the image (S34). If the above processing has not been performed on all the pixels in the image, the above processing is performed on the next pixel (S31 to S35). Thereafter, until the above processing is performed for all the pixels in the image,
The above process is repeated.

As described above, the digital color copying machine can perform the tracking pattern processing even when the color conversion processing is performed when copying the original having the tracking pattern written invisibly or hardly visible together with the image information. Since no color conversion is performed, the original can be copied without deteriorating the image quality and losing the information of the tracking pattern.

As a method of detecting a tracking pattern, in addition to the above-described method, a pattern composed of yellow dots is extracted and stored in a search area in an image area. At this time, the search area is shifted in the image area so as to scan the entire image. After the scanning of the entire image is completed, a common pattern may be detected as a tracking pattern from the stored patterns. Further, it can be detected by using other well-known image pattern recognition techniques.

In this embodiment, an example of application to a copying machine that reads a document image and prints out the read image has been described. However, the present invention receives image information via a network and prints the received image. The present invention can also be applied to an output printing device.

[0036]

According to the present invention, when a document including specific information written invisibly or hardly visible in addition to image information is copied, the image quality can be reduced even when color conversion processing is performed. An image can be printed out without lowering and without losing specific information.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of a digital color copying machine according to the present invention.

FIG. 2 is a diagram showing an operation panel of the digital color copying machine.

FIG. 3 is a block diagram of a read signal processing unit of the digital color copying machine.

FIG. 4 is a block diagram of a print head unit of the digital color copying machine.

FIG. 5 is a flowchart showing a copying operation of the digital color copying machine.

FIG. 6 is a flowchart illustrating a color conversion process.

[Explanation of symbols]

 Reference Signs List 10 scanner 16 operation panel 20 read signal processing unit 31 print head unit 100 image reader unit 200 copying unit 401 printer control unit

Continued on the front page F term (reference) 5C076 AA14 AA40 BA02 BA03 BA04 CA08 5C077 LL14 LL19 MM03 MP08 NN02 PP03 PP06 PP15 PP23 PP32 PP33 PP38 PQ22 RR01 SS02 SS06 TT06 5C079 HB01 HB03 JA23 LA12 LA19 LA21 MA02

Claims (1)

[Claims] 1. An image forming apparatus for printing out an image in which specific information is written invisibly or hardly visible in image information, comprising: input means for inputting an image; printing means for printing the input image; Designating means for designating a color conversion process with a print image; color converting means for transforming the color of an input image based on the designation by the designating means; and detecting means for detecting specific information from the input image Control means for controlling the color conversion means so as not to perform the color conversion processing on a portion of the input image where specific information is detected when the color conversion processing is specified by the specification means; An image creating apparatus comprising: