JP2002218208A - Image processor and image formation device provide with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent image quality even at the time of performing the image formation of the next generation based on formed images. SOLUTION: This image formation device is provided with an image input device 2 for reading input image data, the image processor 3 for processing signals from the image input device 2 and an image output device 5 forming the images on a recording material based on the output image data from the image processor 3. The image processor 3 extracts the high frequency components of image information provided in the input image data and adds and synthesizes additional information for image compensation with the output image data by an information addition means 21.

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 for performing processing so that image quality does not deteriorate even if generation copy is repeated, and an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, when performing an image copying operation in a digital copying machine, image information is simply decomposed into color signals by an input device (image input device) such as a scanner, and a new signal is generated based on this information. In general, image information is copied by forming an image signal and supplying the signal to an output device (image output device).

Japanese Patent Application Laid-Open No. Hei 8-331362 discloses a reading means for reading image data on a document to which image editing information is added, and extracts image editing information of the image data read by the reading means. Editing means for extracting an image of the image data read by the reading means using the image editing information extracted by the extracting means; and an image forming medium for editing the image data edited by the editing means. An image forming apparatus provided with an image forming unit for forming an image is disclosed above.

[0004]

In a conventional digital copying machine, as described in Japanese Patent Application Laid-Open No. 8-331362, image area separation (area separation) for separating a character portion from a gradation portion is performed. Since the image processing suitable for each image is performed using the result, when the generation copy is repeated, the determination of the image area separation is not always the same every time. In terms of characteristics, image quality is likely to deteriorate.

In the method disclosed in the above publication, the image editing information is read and the processing conditions are changed. The contents of the change are included in the characteristic information of the input / output devices (the image input device and the image output device). Since the input device information is not based on the faithfulness, input device information is hardly considered, and the processing content tends to be changed depending on the output device. Therefore,
There is a possibility that processing contents different from the processing image intended when the original image was created may be selected and executed. In other words, since the conditions that can minimize image deterioration and reproduce with less discomfort are not sufficiently satisfied, the color reproduction range differs or the reproducible resolution differs depending on the output device used. Therefore, there is a possibility that improper processing may be executed, and the device is highly dependent on the device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has been made to achieve an image which is capable of obtaining good image quality even when a next-generation image is formed based on the formed image. An object of the present invention is to provide a processing device and an image forming apparatus including the same.

[0007]

An image processing apparatus according to the present invention is used for image processing means for converting input image data into image data for forming an image, and for compensating the image data for forming an image. Information adding means for performing processing for generating additional information, signal synthesizing means for synthesizing the additional information with image data output from the image processing means,
An additional information extracting unit that extracts the additional information from the input image data and outputs the additional information to the image processing unit in order to perform image compensation processing.

In the image processing apparatus according to the present invention, the additional information may be a high-frequency component extracted from input image data, an ICC profile,
More preferably, the high frequency component and the ICC profile extracted from the input image data may be used. Here, when the additional information is a high-frequency component,
The input image data is decomposed into components using a discrete cosine transform method, and high-frequency components are extracted. The additional information is added to the image data output from the image processing unit in the signal synthesizing unit.

If the additional information is an ICC profile, the ICC profile is read by the information adding means and added to the image data output from the image processing means in the signal synthesizing means in the same manner as described above. In this manner, by adding a high-frequency component to the output image data, it is possible to compensate for a high-frequency component that is likely to deteriorate depending on the characteristics of the image input device or the image output device (input / output device). When performing, the reproducibility of the image quality is improved. Further, by adding an ICC profile to the output image data, adjustment according to the characteristics of the input / output device, particularly adjustment of color matching, is facilitated, and the quality of the output image is improved. Further, by adding a high-frequency component and an ICC profile to the output image data, it is possible to compensate for a high-frequency component that is likely to cause image degradation depending on the characteristics of the input / output device, and to adjust the color information of the input / output device. As a result, the quality of the image can be further improved.

The image processing apparatus according to the present invention is characterized in that the signal synthesizing means adds the additional information to a block composed of a plurality of pixels in the image data output from the image processing means. Here, it is preferable that the signal combining means discretely adds the additional information.

As a block including a plurality of pixels to which the additional information is added, when extracting a high-frequency component from input image data, a block used in the discrete cosine transform method or a block used in performing a region separation process for each block. Blocks can be applied, and additional information can be easily added. Further, since the additional information is discretely added to the block, the original image data (by the image input device,
It can be added without deteriorating the quality of input image data read from a document.

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: an image input unit for reading input image data; the image processing device; and a recording medium using a visible color material based on output image data of the image processing device. And image output means for forming an image.

In the present invention, additional information for image compensation is generated by the information adding means, and added to the data for image formation by the signal synthesizing means. Therefore, when further image formation is performed based on the formed image (for example, when performing generation copy), a portion that is likely to be deteriorated depending on the characteristics of an image input device (for example, a scanner) or an image output device (for example, a printer) is determined. By using the additional information, it is possible to compensate in the signal processing process by the image processing means. Therefore, even if the generation copy is repeated, good image quality can be obtained, and the image reproduction characteristics are improved.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the image forming apparatus according to the present invention. In FIG. 1, an image forming apparatus 1 is a digital color copying machine, and includes an image input device (image input means) 2, an image processing device 3, a storage device 4, and an image output device (image output means) 5. The image processing device 3 includes an image processing unit (image processing unit) 10, a signal combining unit (signal combining unit) 20, an information adding unit 21, and an additional information extracting unit 22. Further, the image processing unit 10 includes an A / D conversion unit 11, a shading correction unit 12, an input gradation correction unit 13, an area separation processing unit 14, a black generation / under color removal unit 15, a color correction unit 16, a spatial filter process. It comprises a unit 17 and a tone reproduction processing unit 18.

The image input device 2 is composed of, for example, a scanner unit, and performs an operation of reading an image of a document. The reflected light image from the document is converted into an analog signal of R (red), G (green), and B (blue). (Reflectance signal) as CCD (Charge Couple)
Device). And the A / D converter 11
Is converted into RGB digital signals, and the shading correction unit 12 performs processing to remove various types of distortion generated in the illumination system, the imaging system, and the imaging system of the image input device 2.
The G'B 'signal is output.

Next, R ′ is input by the input tone correction unit 13.
At the same time as adjusting the color balance of the reflectance signal of G'B ', converting the signal into a signal such as a density signal which is easy to handle by the image processing system, and converting the signal into a CMY signal (C: cyan, M: magenta, Y: yellow) (Process of complementing the input image data of R'G'B 'with complementary colors) is performed, and the image data CMY is output.

Next, in the area separation processing section 14, in order to enhance the reproducibility of black characters or color characters in a mixed document of characters and photographs, and to enhance the gradation in the photographic region, each pixel in the input image is divided. The image is separated into any of a character area, a photograph (photographic paper photograph) area, and a halftone dot (print photograph) area.
The region separation processing unit 14 outputs a region identification signal indicating to which region a pixel belongs to the black generation / under color removal unit 15, the color correction unit 16, the spatial filter processing unit 17 based on the separation result.
In addition to the output to the tone reproduction processing unit 18, the input signal output from the input tone correction unit 13 is directly output to the subsequent black generation / under color removal unit 15.

In the image area extracted as a black character by the area separation processing section 14, the black generation amount is adjusted to be high by the black generation / under color removal section 15, and the under color removal amount is determined accordingly. Further, the image area extracted as the print photograph or photographic paper photograph area is determined by the black generation / under color removal unit 15 by the amount of black generation /
The undercolor removal amount is adjusted to an appropriate amount according to the image processing system. Thus, the CMY three-color signals are CMYK (K:
(Black) four-color signals.

The color correction section 16 performs a process of removing color turbidity based on the spectral characteristics of CMY color materials including unnecessary absorption components and a color matching process between a document and a copy in order to realize faithful color reproduction. Then, a signal of C′M′Y ′ is output.

Next, in the spatial filter processing unit 17, the obtained image signal is subjected to spatial filter processing by a digital filter, and the spatial frequency characteristics are corrected to prevent blurring and graininess deterioration of the output image. The processing is performed to output a C "M" Y "K 'signal. For example, the area separation processing unit 14 extracts a black character in order to enhance the reproducibility of a black character and the like in a mixed document including characters and photographs. In the image area, the enhancement amount of the high frequency is increased by the sharpness enhancement processing in the spatial filter processing unit 17.

On the other hand, the area determined to be a print photograph by the area separation processing section 14 is subjected to a low-pass filter processing for removing an input halftone dot component in a spatial filter processing section 17 to obtain a photographic paper photograph. The determined area is subjected to slight emphasis or smoothing processing in the spatial filter processing unit 17 according to the system (digital color copying machine). The tone reproduction processing unit 18 performs optimal binarization or multi-value processing based on the region identification signal by using a tone reproduction process such as an error diffusion process or a dither process.

The image data (C
out, Mout, Yout, Kout) are combined with the signal obtained by the information adding means 21 in the signal combining unit 20, and the image output signals (C'out, M'out, Y'out, K'out) are obtained.
Generate Here, the information adding unit 21 generates additional information by processing the CMY signal output from the input tone correction unit 13 (described in detail later). This additional information is information for compensating for an image portion that is easily deteriorated depending on the characteristics of the so-called input / output devices of the image input device 2 and the image output device 5.

C'out, M'out, Y'out, K'out
The signal is temporarily stored in the storage device 4, read out at a predetermined timing, and input to the image output device 5. The image output device 5 outputs image data on a recording medium (for example, paper), and includes, for example, a mono-color or color image output device using an electrophotographic system or an inkjet system. There is no particular limitation.

CMY output from the input tone correction unit 13
The signal is also input to the additional information extracting unit 22, and the additional information extracted from the additional information extracting unit 22 is supplied to the segmentation processing unit 14, the black generation / under color removal unit 15, and the color correction unit 1.
6. Spatial filter processing unit 17 and gradation reproduction processing unit 18
Is input to In this way, each part of the image processing unit 10 performs compensation processing on a part that is easily deteriorated.

FIG. 2 is a block diagram showing an example of the information adding means. The high-frequency component information is obtained by, for example, a discrete cosine transform coding method (Discrete C
The image information is converted into frequency component information using a sinusoid transform (hereinafter, referred to as DCT). In this case, the input image data input to the information adding means is input
3 is a CMY signal output from the CMY. At this time, high frequency component information (for example, 600 dp
Component information about i (dot per inch)) is used as additional information.

As an example of the DCT technique, generally, JPE
It is also possible to use a method used in G (Joint Photographic Experts Group) image compression or the like. For example, the input image data is converted into a block of 8 × 8 pixels, and an orthogonal transform (discrete cosine transform) is performed on the block.
I do. As a result of the conversion, 64 coefficients are obtained, which are decomposed into a DC (direct current) component, a horizontal frequency component, and a vertical frequency component, and are represented by a linear combination of basis vectors.
The coefficients obtained at this time represent frequency components. Such processing is performed by the DCT processing unit 30.

Of these, only necessary high-frequency component information is extracted by the high-frequency signal selector 31 and converted into additional information (digital signal) by the signal conversion unit 32 by using a reversible encoding technique such as Huffman encoding. Then, the signal synthesizing unit 2 of FIG.
At 0, the image data is synthesized with the image data obtained by the image processing unit 10. When the information in which the high-frequency component information is recorded is used for the image data (when the high-frequency component information is extracted by the additional information extracting unit 22 in FIG. 1), the inverse DCT is used.
Using the high-frequency component signal obtained by performing the conversion, the image processing unit 10 compensates for a signal that is easily lost. Since the additional information is a high-frequency component of the input image signal, it is possible to compensate for a high-frequency component which is likely to be deteriorated particularly depending on the characteristics of the input / output device, thereby improving the reproducibility of the image quality even in the generation copy.

When converting image information into frequency component information using the DCT technique, if the system can obtain the identification information for each block, such as the block recognition information, the segmentation processing unit 14 pairs the information with the information. Can also be used. Alternatively, it is also possible to use the block information and the area identification signal when using the DCT technique as a pair. Since the low-frequency component can be sufficiently detected by a normal scanner and can be reproduced by the image processing unit 10, it is not used for additional information in this system.

FIG. 3 is a block diagram showing another example of the information adding means. ICC (International Color Consorti
um) Profile information (unified standard of each company such as a color management system for correcting color characteristics unique to input / output devices) is composed of information as shown in FIGS. That is, FIG. 4 shows an example of the ICC profile format configuration, and the tag table 3
5 and element data 36. FIG.
Is an example of a tag table, and includes a tag name 37 and a description 38 thereof. Since such information can be created using a commercially available ICC profile creation tool, the information is created in advance as information on an image input device or an image output device, and the data is incorporated and added as additional information. It is also possible to use.

The ICC profile information is stored in the ICC profile information storage 34. This information
The signal is read out by the signal conversion unit 33 and converted into a format that can be easily used for adding information by using a reversible coding method such as the Huffman coding method. Is combined with the obtained image data. Since the ICC profile is added to the image data as additional information in this way, adjustment of characteristics according to input / output devices, particularly adjustment of color matching, can be easily performed, so that image reproduction characteristics can be improved.

FIG. 6 is a diagram for explaining a state in which additional information is added to image data. The additional information 40 is added to the image data output from the image processing unit 10 in the signal synthesis unit 20. At this time, the additional information 40 is discretely added to a block 41 including a plurality of pixels (for example, about 10 pixels). Thus, the image information 40 can be added more effectively without lowering the quality of the original image data. As described above, when the area separation processing unit 14 uses the algorithm for determining the area identification signal for each block, as described above, a block for the area separation processing can be used. Alternatively, a block processed by DCT may be used.

As an example of adding information, the information is added as density information to a Y (yellow) signal which is hardly noticeable to human eyes. The processing for reading out the additional information is performed by the additional information extracting means 22 shown in FIG. 1, and the Y signal component is extracted from the input image data (the CMY signal subjected to the input gradation correction processing) read by the image input device 2. , The maximum width of density information is 1
Quantization is performed using an appropriate threshold value divided into about six steps, an additional information signal is extracted, and the extracted signal is decoded. At this time, inverse DCT is performed on the high frequency component information,
The ICC profile information is subjected to decoding processing and is read by digital processing as an information signal.
The read information is supplied to an area separation processing unit 14, a black generation / under color removal unit 15, a color correction unit 16, and a spatial filter processing unit 1.
7. The image data is input to the tone reproduction processing unit 18 and appropriate image processing is performed on the input image data.

For example, when the read information is high-frequency component information, the area separation processing unit 14 refers to the high-frequency information component and determines appropriate parameters (complexity, etc.) when performing area separation. Is set. And
In order to hold high frequency components, the spatial filter processing unit 17
Then, a filter process that preserves edges is performed. When dither processing is used, the tone reproduction processing unit 18 performs processing using a small-sized dither matrix. If the read information is an ICC profile, the black generation / under color removal unit 15 performs appropriate black generation and under color removal, and a color correction unit 16 so that optimal color reproduction is performed according to the information. Then, an appropriate color correction table is selected and color correction processing is performed.

In the above description, high frequency components and I
Although the case where the CC profiles are used individually has been described, both may be used. Additional information is high frequency component and ICC
The profile makes it easy to reproduce high-frequency information and color signal information, which are likely to cause image degradation depending on the characteristics of the input / output device, and improve image reproduction characteristics.

[0036]

As described above in detail, according to the present invention, additional information for image compensation is generated by the information adding means and added to the data for image formation by the signal synthesizing means.
Since the additional information is extracted by the additional information extracting unit and the image processing unit performs the image compensation process, when further image formation is performed based on the formed image (for example, when performing generation copy), the characteristics of the input / output device , The portion which easily deteriorates is compensated, and the image reproduction characteristics are improved.

Further, according to the present invention, since the additional information is a high-frequency component of the input image data, it is possible to compensate for a high-frequency component which is liable to be deteriorated particularly depending on the characteristics of the input / output device. High reproducibility.

Further, according to the present invention, the additional information may be an ICC
With the profile, adjustment of characteristics according to input / output devices, particularly adjustment of color matching, can be easily performed, so that image reproduction characteristics can be improved.

Further, according to the present invention, since the additional information is a high-frequency component and an ICC profile, it is easy to reproduce high-frequency information and color information which easily cause image degradation depending on the characteristics of the input / output device. Thus, the image reproduction characteristics can be improved.

Further, according to the present invention, by performing input image data by using a discrete cosine transform method, information which is relatively common in the field of image processing and which can easily obtain information corresponding to frequency components is obtained. Therefore, image processing accuracy can be improved without increasing the circuit scale.

Further, according to the present invention, image information (additional information) to be added to output image data is discretely added to a block including a plurality of pixels, so that the added image information can be dispersed. Image information can be added without lowering the quality of the original image data. Further, when the discrete cosine transform method is used or when the area separation processing method is used for each block, the processing is performed for each block, so that image information can be easily added.

According to the present invention, since image information is discretely added to a plurality of blocks, image information can be added more effectively without deteriorating the quality of the original image data.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an example of an information adding unit.

FIG. 3 is a block diagram showing another example of the information adding unit.

FIG. 4 is a diagram illustrating a format configuration of ICC profile information;

FIG. 5 is a diagram showing an example of a tag table constituting ICC profile information.

FIG. 6 is a diagram illustrating a state in which additional information is added to image data.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image forming apparatus 2 image input apparatus (image input means) 3 image processing apparatus 5 image output apparatus (image output means) 10 image processing section (image processing means) 20 signal synthesis section (signal synthesis means) 21 information addition means 22 addition Information extraction means

Claims (8)

[Claims] 1. An image processing means for converting input image data into image data for forming an image, and an information adding means for generating processing for generating additional information used for compensating the image data for forming an image. A signal synthesizing unit that synthesizes the additional information with the image data output from the image processing unit; and extracting the additional information from the input image data and outputting the extracted additional information to the image processing unit to perform image compensation processing. An image processing apparatus comprising: additional information extracting means. 2. The image processing apparatus according to claim 1, wherein the additional information is a high-frequency component extracted from input image data. 3. The image processing apparatus according to claim 1, wherein the additional information is an ICC profile. 4. The image processing apparatus according to claim 1, wherein the additional information is a high-frequency component extracted from input image data and an ICC profile. 5. An image processing apparatus according to claim 2, wherein said information adding means decomposes the input image data into respective components using a discrete cosine transform method and extracts high frequency components. 6. The image processing apparatus according to claim 1, wherein the signal synthesizing unit adds the additional information to a block including a plurality of pixels in the image data output from the image processing unit. The image processing apparatus according to any one of the preceding claims. 7. The image processing apparatus according to claim 6, wherein said signal combining means discretely adds said additional information. 8. An image input unit for reading input image data, an image processing device according to claim 1, and a visible color material based on output image data of the image processing device. An image forming apparatus comprising: an image output unit that forms an image on a recording medium.