JPH09186863A - Method and device for image processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain image recognition with high accuracy from density image data. SOLUTION: Received RGB image data are given to an RF converter 2, in which color space conversion and correction processing are conducted and YMCK image data are obtained. A gamma table to which a conversion table is set by an analysis section 3 is used to apply inverse-processing to the YMCK image data outputted from the RF converter 2 to restore the data to the original RGB image data. An image recognition circuit 7 recognizes the image of a specific original from the RGF3 image data outputted from th gamma table 6. A printer engine 4 provides the output of a signal 8 used to request input of patch data in a predetermined color at the initialization. The color patch data received by the signal 8 and processed by the RF converter 2 are given to the analysis section 3 and the conversion table to be set to the gamma table 6 is obtained.

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 a method thereof, for example, an image processing apparatus and a method thereof for recognizing the identity between an image represented by input image data and a specific image.

[0002]

2. Description of the Related Art Color printing could only be done before by professional printers, but with the widespread use of color copiers and color printers, anyone can easily perform high-quality printing. The full-color prints of are now readily available.

However, while these devices have become popular,
Technology is required to prevent counterfeiting of manuscripts (hereinafter referred to as "specific manuscripts") that should not be reproduced due to legal restrictions such as banknotes and securities, etc. Is becoming. In this technique, reference data is created in advance from image information of a specific document, and it is determined based on the reference data whether the input image is the specific document. Most of these technologies attempt to prevent forgery by developing input image data on a memory, performing pattern matching or fuzzy inference on the memory, and extracting feature points of a specific document. .

Furthermore, regarding the data to be detected, the RGB
YMCK, which is the color space of the printer and the device that detects in the color space
There is a device for detecting in the color space. On the other hand, recent image processing software can handle image data in either RGB or YMCK color space.

FIG. 1 is a block diagram showing a configuration example of a printer. Image data 1 in RGB color space input from an input device such as a host computer or an image scanner (not shown).
01 is converted into image data 103 in the YMCK color space which is the color space of the printer by the reproduction converter (hereinafter referred to as “RF converter”) 102. The RF converter 102 performs conversion from the RGB color space to the YMC color space, and also performs undercolor removal (hereinafter referred to as “UCR”) and masking processing for correcting characteristics such as toner. And the image data
103 is input to the printer engine 104, and Y, M, C, and K color component images are superimposed and output as a color image output 105.

Since the printer is an image forming apparatus that forms a color image by the subtractive color method, YMCK or YMC converted image data is finally input to the printer engine 104 regardless of the color space of the input data. . Further, image processing software (for example, printer driver) running on the host computer may perform RF conversion. In that case, image data in the YMCK color space is directly input from the host computer to the printer. Therefore,
It can be said that proper image recognition is performed in the YMCK or YMC color space.

[0007]

However, the above-mentioned technique has the following problems. That is, in the RGB color space, the luminance information can be linearly approximated as it is, but YMCK data needs to be approximated by log conversion, and the amplitude of each YMC data is compressed by UCR processing. . Furthermore, since corrections have been added to correct various characteristics of the printer engine,
It is difficult to faithfully reproduce the original luminance information in RGB space from YMCK image data. Therefore, YMCK or YM
There is a problem that it is not possible to perform highly accurate image recognition from C image data.

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and an object of the present invention is to provide an image processing apparatus and method capable of performing highly accurate image recognition from density image data.

It is another object of the present invention to provide an image processing apparatus and method capable of performing highly accurate image recognition even when the characteristics of the processing performed on the density image data are unknown.

[0010]

The present invention has the following configuration as one means for achieving the above object.

The image processing apparatus according to the present invention comprises processing means for subjecting the input image data subjected to a predetermined conversion processing to inverse conversion processing of the conversion processing based on processing conditions set by the setting means. And a recognition unit that recognizes whether or not the image represented by the image data subjected to the inverse conversion processing by the processing unit is a specific image, and the setting unit obtains the processing condition from the input predetermined reference data. Characterize.

Further, the color space conversion is performed on the basis of processing means for performing color space conversion and correction processing on the input image data, and processing conditions set by the setting means for the image data processed by the processing means. And reverse processing means for performing reverse processing of correction processing, recognition means for recognizing the image represented by the image data processed by the reverse processing means, and processing by the processing means based on the recognition result obtained by the recognition means. Output means for controlling the output of the image data, and the setting means obtains the processing condition from predetermined reference data input at a predetermined timing and processed by the processing means.

According to the image processing method of the present invention, a process step of subjecting the input image data subjected to a predetermined conversion process to an inverse conversion process of the conversion process based on the processing condition set in the setting step, A recognition step of recognizing whether or not the image represented by the image data subjected to the inverse conversion processing in the processing step is a specific image, and the setting step obtains the processing condition from input predetermined reference data. And

Further, based on the processing step of performing color space conversion and correction processing on the input image data, and the color space conversion and correction processing based on the processing conditions set in the setting step for the image data processed in the processing step. A reverse processing step of performing a reverse processing of the correction processing, a recognition step of recognizing an image represented by the image data processed in the reverse processing step, and an image data processed in the processing step based on a recognition result obtained in the recognition step. An output step for controlling output, wherein the setting step obtains the processing condition from predetermined reference data input at a predetermined timing and processed in the processing step.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0016]

First Embodiment FIG. 2 is a block diagram showing a configuration example of an image processing apparatus according to an embodiment of the present invention.

In FIG. 1, an RGB digital image signal 1 input from an input device such as a host computer (not shown) is converted into a YMCK digital image signal by an RF converter 2. The RF converter 2 performs conversion from the RGB color space to the YMC color space, and also performs masking processing for correcting characteristics such as UCR and toner. When the YMCK digital image signal is directly input by the image processing software running on the host computer, the RF converter 2 commands the host computer to pass the input signal as it is, or an operation panel (not shown) or the like. It is set from.

The YMCK digital image signal output from the RF converter 2 is input to the γ table 6 composed of the printer engine 4, RAM and the like and the analyzing means 3. The printer engine 4 forms a color image based on the image data from the RF converter 2 and outputs a print output 5.

On the other hand, the digital image data converted by the γ table 6 is input to the image recognition circuit 7.
The image recognition circuit 7 stores reference data created from image information of a specific document, performs pattern matching or fuzzy inference based on the reference data, and identifies the image represented by the converted digital image data. If the original is recognized, and if the original is recognized, the operation of at least a part of the process means of the printer is changed to interrupt the printing, or the image data is changed to, for example, a black solid image. A control signal for controlling the apparatus is output to the printer engine 4 so as to prevent the image of a specific document from being printed out faithfully by taking measures such as forming an image.

Here, the conversion table of the γ table 6 is set by the analysis unit 3, and its setting operation will be described.

The printer engine 4 is an image running on the host computer (or an image running on the host computer) at the time of initializing the power supply of the printer or at the time of resetting, and when the color space of the input data is changed from the operation panel or the like. A signal 8 for requesting output of predetermined color patch data is output to the processing software). here,
The printer engine 4 does not execute printing until the color patch data that is predetermined according to the request signal 8 is input.

The color patch data of the RGB color space output from the host computer which receives the request signal 8 is converted and corrected by the RF converter 2 and input to the analysis unit 3. In addition, the image processing software that receives the request signal 8 converts the RGB digital image data of the predetermined color patch and outputs the color patch data of the YMCK color space that is output after being corrected and input to the analysis unit 3 as it is. To be done.

The analysis unit 3 obtains a correlation between the inversely converted data from the YMCK color space to the RGB color space and the predetermined color patch data stored in the internal memory of the analysis unit 3 in advance. From this correlation, the optimum conversion table for converting the YMCK image data output from the RF converter 2 or the directly input YMCK image data into RGB image data is written in the γ table 6.

The image signal converted from the YMCK color space to the RGB color space by the conversion table of the γ table 6 thus obtained is subjected to color space conversion by the RF converter 2 (or RF conversion by image processing software) and The effects of various corrections have been removed. RF conversion performs various processes such as color space conversion, UCR, masking, and correction of engine characteristics, so the YMCK image data that is output is affected by UCR.
The data has apparently reduced image contrast. That is, the γ table 6 removes the influence of various characteristics of the RF converter 2 (or RF conversion by image processing software),
Works to reproduce the original RGB digital image data.
Furthermore, by rewriting the conversion table of the γ table 6 by inverse RF conversion using color patch data, the effect of RF conversion can be accurately removed even if the characteristics such as RF conversion by image processing software are not known. Will be possible.

Therefore, the γ table 6 can remove the influence of the RF conversion from the image data, and as a result, the contrast of the image data can be improved and the accuracy of recognizing the image of the specific original can be improved. You can

As described above, according to the present embodiment, even when the input RGB image data is subjected to RF conversion in the apparatus, R
Even when the F-converted YMCK or YMC image data is directly input, it is possible to accurately recognize the image of the specific original from the YMCK or YMC image data, and if it is the image of the specific original, print it. It is possible to prevent the faithful print output of a specific original by stopping the process, performing process control such as not fixing, or deforming the image data into a black solid image, for example.

[0027]

Second Embodiment Hereinafter, an image processing apparatus according to a second embodiment of the present invention will be described. In the second embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 3 is a block diagram showing an example of the arrangement of an image processing apparatus according to the second embodiment of the present invention.

The printer engine 4 prints out the color patch data input in response to the request signal 8 as in the above-described embodiment. In response to an instruction from the operation unit 11, the image input unit 9 reads the print output 5 of the color patch data using the color image scanner 10, and inputs the read image data in the RGB color space to the analysis unit 3. Then, the analysis unit 3 obtains the correlation as in the above-described embodiment, and writes the conversion table obtained from the data indicating the correlation in the γ table 6.

Here, the printer engine 4 sends the request signal 8
When is output, printing is not executed except for the image signal input according to the same signal. Further, the operation unit 11 is provided with a printer until the printer 5 is instructed to read the print output 5 after the power is turned on or reset and when the color space of the input data is changed, and the analysis of the analysis unit 3 is normally completed. It functions to limit the printing of engine 4.

The color image scanner 10 does not necessarily have to be built in the printer, and an external device such as a colorimeter may be used. In this case, the print output is read not on the photosensitive drum or the transfer drum but on the recording medium such as recording paper.

[0032]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

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 a CPU or MPU) of the system or the apparatus.
Needless to say, this can also be achieved by the PU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements 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, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM,
CD-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Moreover, not only the functions of the above-described embodiments are realized by executing the program code read by the computer, but also the OS (operating system) running on the computer based on the instructions of the program code. It is needless to say that this also includes a case where the above) performs a 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 in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU included in the function expansion card or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

In each of the above-described embodiments, an example in which the color space of the input image data is RGB, YMCK, or YMC has been described, but the present invention is not limited to this.
It goes without saying that it is possible to support data in any color space (for example, Lab, Luv, YCrCb, XYZ, YIQ, HSI, etc.).

Further, the γ table 6 and the image recognition circuit 7
Can also be configured for each color component data.

Further, one of the color component data output from the γ table 6 is selected based on the processed color signal from the printer engine 4, and the selected one color component data is input to the image recognition circuit 7. Image recognition may be performed. Also,
It is also possible to control the color component data to be selected according to the print mode (YMCK four-color printing or YMC three-color printing).

The processing conditions for the color space conversion and correction processing of the RF converter 2 can be configured to be changeable from an external device (such as a host computer) or the operation unit 11, and the processing conditions can be changed. The color can be changed for each YMCK color or according to the print mode (YMCK four-color printing or YMC three-color printing), but the present invention is also effective in these cases.

Further, although the γ table has been described as a LUT (Look Up Table) in each of the above-described embodiments, the present invention is not limited to this, and a converter having one input and one output may be used. It goes without saying that the same effect can be obtained even if it is configured by a device, software, and the like.

[0041]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and method for performing highly accurate image recognition from density image data.

Further, it is possible to provide an image processing apparatus and method for performing highly accurate image recognition even when the characteristics of the processing performed on the density image data are unknown.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a printer,

FIG. 2 is a block diagram showing a configuration example of an image processing apparatus according to an embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration example of an image processing apparatus according to a second embodiment of the present invention.

Claims (10)

[Claims] 1. The input image data, which has been subjected to a predetermined conversion process, based on a processing condition set by a setting means,
The setting means is provided with a processing means for performing an inverse conversion processing of the conversion processing, and a recognition means for recognizing whether or not the image represented by the image data subjected to the inverse conversion processing by the processing means is a specific image. An image processing apparatus, wherein the processing condition is obtained from predetermined reference data. 2. A color space conversion means for applying color space conversion and correction processing to the input image data, and the color space conversion based on the processing condition set by the setting means for the image data processed by the processing means. And inverse processing means for performing inverse processing of correction processing, recognition means for recognizing the image represented by the image data processed by the inverse processing means, and processing by the processing means based on the recognition result obtained by the recognition means. Output means for controlling output of the image data, wherein the setting means obtains the processing condition from predetermined reference data input at a predetermined timing and processed by the processing means. apparatus. 3. The image processing apparatus according to claim 2, wherein the recognition unit is for recognizing an image of a specific document. 4. The image according to claim 3, wherein when the recognition unit recognizes the image of the specific document, the output unit does not output the image data processed by the processing unit. Processing equipment. 5. The image processing apparatus according to claim 1, wherein the setting unit obtains the processing condition from image data of a predetermined color patch. 6. The image processing apparatus according to claim 1, wherein the predetermined reference data is input when the image processing apparatus performs an initialization operation. 7. The image processing apparatus according to claim 2, wherein the color space conversion is conversion from a luminance color space to a density color space. 8. The image processing apparatus according to claim 2, wherein the correction processing includes UCR, masking, and density correction processing. 9. The input image data that has been subjected to a predetermined conversion process, based on the processing conditions set in the setting step,
The method includes a processing step of performing an inverse conversion processing of the conversion processing, and a recognition step of recognizing whether or not the image represented by the image data subjected to the inverse conversion processing in the processing step is a specific image, and the setting step is input. An image processing method, wherein the processing condition is obtained from predetermined reference data. 10. A processing step of performing color space conversion and correction processing on input image data, and the color space conversion and correction processing based on the processing conditions set in the setting step of the image data processed in the processing step. An inverse processing step of performing an inverse processing of the correction processing, a recognition step of recognizing an image represented by the image data processed in the inverse processing step, and an image data processed in the processing step based on a recognition result obtained in the recognition step. An image processing method comprising: an output step of controlling an output, wherein the setting step obtains the processing condition from predetermined reference data input at a predetermined timing and processed in the processing step.