JP2003283832A - Image processing apparatus, image processing method and color copying machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus having a background clearing circuit in which the intention of a user is realized as much as possible without performing pre-scan and almost without requiring the addition of hardware, using a local storage memory, an image processing method and a color copying machine. <P>SOLUTION: In addition to base clearing 203b-1 on the side of RGBm background clearing 203b-2 on the side of CMYK processing is added after the expansion of data read out of a storage means 105. The storage means 105 stores the image data of CMYK surface-sequentially while attaching background clearing notch information, show-through effects prevention notch information and original background density information to the header portion of an image data memory as additional information, and the background clearing 203b-2 is performed by using such additional information. <P>COPYRIGHT: (C)2004,JPO

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, an image processing method and a color copying machine, and more particularly to an image processing apparatus and an image processing method suitable for use in a digital full color copying machine having a background removal function. And color copiers.

[0002]

2. Description of the Related Art As conventional techniques relating to an image processing apparatus having a background removal function, for example, 1. Japanese Patent Laid-Open No. 10-1738
74, 2. Japanese Patent Laid-Open No. 11-298694,
3. Techniques described in Japanese Patent Laid-Open No. P11-144047 are known.

Conventionally, a copying machine having a color image processing device generally removes the background from various aspects. One is to cut the background density of non-white originals such as rough paper or newspaper.
One is called show-through prevention, and when an original exists on both sides of a paper, if the paper is thin, the back side information is reflected in the copy result even if it is the back side. The technique described in the aforementioned publication 1 is an example of background removal for a color background document, and the technique described in publication 2 is an example of show-through prevention. In both cases of color originals and show-through originals, it is desirable for the user to remove the background cleanly without being aware of that fact, but in reality, restrictions and significant addition of hardware are required. .

In the prior art described in Publication 1, the density of each pixel of the document is detected at the time of Bk (black) image formation which is the first scan, and the background density is detected by detecting the density peak, and the second scan is performed. After that, that is, the background is removed at the time of plate image formation of C (cyan), M (managenta), and Y (yellow). In order to create a full-color image, this process does not form an image of one color of Bk plate, but a CMY plate 3 even if it is gray for a part having a low density such as background density (hereinafter referred to as highlight). This is a process that is supposed to be developed by color overlapping (hereinafter referred to as low UCR). However, this conventional technique has a problem in that a yellow color, which is the background density, is noticeable around the text portion of a newspaper manuscript, and the text portion is photographed so that it becomes blurred. Character processing that develops with (hereinafter called high UCR) is desirable. That is, there is a strong demand for removing the background density of the original even for Bk development, and in reality, it is often found that there are several types of removal amounts that can be selected and the background removal is performed at a constant density.

Further, in the prior art disclosed in Japanese Patent Laid-Open No. 2004-331, a liquid crystal shutter is provided on a pressure plate for pressing an original to detect the size of the original, and the transmitted light of the original is not reflected at the time of reading the original so that the show-through occurs. There is a problem in that the pressure plate becomes very expensive, which is not realistic. Therefore, it is often found that the show-through is prevented by removing the background with a certain density by using several types so that the removal amount can be selected similarly to the color background document.

As described above, the prior arts disclosed in Japanese Patent Laid-Open Nos. 1 and 2 perform background removal at a certain level of density, but in recent years, they are called local storage as described in Japanese Laid-Open Patent Publication No. 3-5. The number of image data of a plurality of originals stored in a memory and sharing the data via a network is increasing. In the case of normal copying, it suffices to input the copy conditions from the operation unit and perform image processing according to the instructions, but when using the local storage, only the image data is loaded into the memory,
The print conditions will be specified again at the time of printing.

[0007]

In the case of removing the background by using the conventional technique described in the above-mentioned publication 3, if the background removal is performed when the image data is loaded into the memory, the background will be printed later. Unable to retrieve information,
Further, if the reproduction of the highlight density is different as a characteristic of the printer, it is impossible to correct it.

An object of the present invention is to solve the above-mentioned problems of the prior art and to use the local storage memory without pre-scanning, hardly adding any hardware, and reflecting the user's intention as much as possible. An object of the present invention is to provide an image processing apparatus, an image processing method, and a color copying machine having a possible background removal circuit.

[0009]

To achieve the above object, a first means is image input means for reading a document, means for detecting a highlight density of image data obtained by the image input means, and reading means. First removing means for removing the highlight density of the acquired image data, storage memory means for accumulating the image data from the removing means, and the accumulated image data are read again, and the highlight density of the image data is determined. In an image processing apparatus having a second removing unit for removing and a unit for printing image data from the second removing unit, background removal amount designation key information and high level information are added to the top of the storage memory unit as additional information. Whether to invalidate the first removing means depending on means for accumulating the result of the light density detecting means and whether or not to use the image data of the accumulating memory means Characterized in that it comprises a means for switching whether to effect.

A second means is characterized in that the background removal key information is used as the background removal amount designation key information.

A third means is characterized in that information of a show-through prevention key is used as the background removal amount designation key information.

A fourth means reads a document and inputs it,
The highlight density of the input image data is detected, the highlight density of the image data is removed, the subsequent image data is stored, then the stored image data is read again, and the highlight density of the image data is removed. In the image processing method of printing the image data, the background removal amount designation key information and the highlight density detection result are accumulated as additional information at the beginning of the accumulation of the image data, and the image data is accumulated. Depending on whether or not to use
It is characterized in that the highlight removal before the image data accumulation is switched between invalid and valid.

A fifth means is characterized in that information of a background removal key or information of a show-through prevention key is used as the background removal amount designation key information.

A sixth means is characterized in that the color copying machine is provided with the image processing apparatus according to the above-mentioned first, second or third means.

According to the above-mentioned first to fifth means, the background removal amount designating key information as the additional information and the result of the highlight density detecting means can be accumulated at the head of the accumulating memory means, and the accumulating memory means Even when image data is used, the above-mentioned two pieces of information can be used, the print of the same image quality can be maintained regardless of whether or not the storage memory is used, and further, the background removal can be performed by the printer's high level. It can be done according to the light characteristics.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image processing apparatus according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a digital color copying machine using an image processing apparatus according to the present invention.

In FIG. 1, image data read by the scanner 101 is subjected to image processing by an IPU (image processing unit) 102 and output to a printer 103, which is a rough flow of the image path. The operation unit 10 has a function of notifying the scanner 101, the IPU 102, and the printer 103 of various settings.
4 is in charge. In the embodiment of the present invention shown in FIG. 1, the IPU 102 is connected to a storage unit 105 having a memory called a local storage capable of storing an image of one frame or more.

FIG. 2 shows the IP in FIG. 1 in the case of the prior art.
It is a figure explaining the internal structure of U102, and the flow of a process.
First, the flow of the image path will be briefly described.

The image data input from the scanner 101 is input to the scanner gamma 201 and the image area separation 209. The image area separation 209 calculates the image feature amount from the input image data, determines in real time whether the document is a character area, a photographic area, or another area, and determines each image processing block after the scanner gamma 201. It has a function to output the judgment result to. The scanner gamma 201 has a function of converting linear reflectance data from the scanner 101 into density linear characteristics. After the processing in the scanner gamma 201, the image data is processed by the filter processing 202, the background detection &
The background removal 203, the color correction & UCR / UCA 204, and the compression 205 are sequentially performed, and the image data subjected to these processes is stored in the storage unit 105.

According to the determination result of the image area separation 209, the filter processing 202 executes edge enhancement processing for MTF correction in the case of a character area, and executes smoothing processing for preventing halftone dot moire in the case of a photograph area. . The background detection & background removal 203 is a process that is the basis of the present invention.
One document background density is detected for one document read in 1 and the background removal is performed according to the value. Color correction & UCR / UCA204 is R (red), G (green), B
Each of the (blue) data is subjected to complementary color conversion into each of C, M, and Y data, the Bk amount is calculated from the converted CMY data, and image data for four CMYBk colors that are the base of the print ink is created. The image data for the four CMYBk colors is stored in the storage unit 105.
If the size is 600 dpi, the image data has a large capacity of 280 Mbytes, so the image capacity is compressed by the compression 205 to reduce the memory capacity. For example, when 1/4 compression is performed, the total capacity is 70 Mbytes. The image data read from the storage unit 105 is processed by the expansion circuit 206 and the printer gamma 20.
7. The flow proceeds to gradation processing 208.

There are two image paths, one for reading out four colors of CMYK at the same time and one for reading out only one color.
In the case of reading out four colors of CMYK at the same time, these four colors are input to four drums in parallel and printed, and in the case of reading out one color of CMYK, these four colors are read into one drum. Input serially and print.

The decompression circuit 206 is a circuit for decompressing the data compressed by the compression circuit 205 and accumulated in the accumulating means 105, and then read out.
Inverse correction of the characteristics of the printer body and the gamma characteristics of gradation processing is performed so that the output sample is density linear. The gradation processing 208 performs resolution-oriented gradation processing in the case of a character area and gradation-oriented gradation processing in the case of a photographic area according to the determination result of the image area separation 209. There is a process called ACS 210 which is performed in parallel with the process of the scanner gamma 201 and the image area separation 209. This process is peculiar to a one-drum machine and determines whether the read document is a color document or a monochrome document. This is for performing Bk development only and printing out when it is a monochrome original.

Each process in the IPU 102 is one IPU
It is connected by a bus, and various parameters are set and controlled by the CPU 211. At that time, RAM212
Is a work memory of the CPU 211, and a ROM
Various setting parameters and the like are stored in 213 and used. The actual setting of parameters is performed by selecting various settings on the operation unit 104 and performing serial communication between the values in the CPU of the operation unit 104 and the CPU 211 of the IPU 102.

FIG. 3 is a simple block diagram for explaining the configuration of the operation unit 104 and the configuration of its peripheral elements. As shown in FIG. 3, the operation unit 104 includes an operation panel 30.
0, a CPU 301 that controls the entire operation unit 104,
A RAM 302 and a ROM 303 are connected to each other by an internal bus. In FIG. 3, the IPU 102
The CPU 211 of the IPU 102 and the CPU 301 of the operation unit 104 are each provided with a serial I / F.
Various parameters selected and set by the operation of IPU10
It is transmitted to the 2 side. Further, FIG. 3 shows that the background detection / background removal 203 described above is configured by a background detection unit 203a and a background removal unit 203b.

FIG. 4 is a block diagram showing the detailed structure of the background detection and background removal 203 in the case of the prior art on which the present invention is based, FIG. 5 is a view showing the structure of the state machine in FIG. 4, and FIG. 4 is a diagram showing the structure of the background density determination 403 in FIG. 4, and FIG. 7 is a time chart explaining the writing timing to the background density register. Next, the background detection & background removal 203 will be described with reference to these figures. .

As shown in FIG. 3, the background detection & background removal 203 is composed of a background detection section 203a and a background removal section 203b, and the background detection section 203a is, as shown in FIG. It comprises a minimum value detection 402 and a background density determination 403. A background density register is provided in the background density determination 403, and one background density is detected for one document.

The state machine 401 generates an effective area for performing background density determination as shown in FIG. 5, and includes an effective area LGATE in the main scanning direction and an effective area F in the sub-scanning direction.
An effective area is generated according to the AND condition with GATE. Then, the information indicating the generated effective area is the background density determination 4
It is input to 03. Further, the minimum value detection 402 shown in FIG.
Is a function of detecting the minimum value from the input RGB data and outputting it, and is composed of a simple comparator of three RGB data.

The background density determination 403 includes two types of background density registers F / F 4034 and 4035 as shown in FIG. F / which is the background density register
The F4034 functions as a tmp register, and the other background density register F / F4034 functions as a main register. In the background density determination 403, the preset background density initial value and the value held by the F / F 4034 as the tmp register are further input, and the signal E of FIG. 7 indicating the effective area output by the state machine 401 is input.
A selector 4031 for selecting a value held by the F / F 4034 as a tmp register when N is “1” indicating that the area is a valid area, and the above-described minimum value detection 4
02 minimum background density output by 02 and the selector 43 described above.
01 is compared with the value output by 01 to output a comparison result indicating which is smaller, the minimum value of the background density output by the minimum value detection 402 described above, and the value output by the selector 4301 described above. The smaller value is input according to the comparison result from the comparator 4032 described above, and the F / F4034 as the tmp register is output.
And a selector 4033 for latching to.

With the configuration as described above, the brightest (minimum value) point in the effective area is updated and latched in the F / F 4034 as the tmp register in pixel clock units. And F / F as this register
4035 is updated with the tmp register in the valid area, but the valid area is closed (negotiated)
The value of the tmp register at the point, that is, the point at which the signal EN in FIG. 7 becomes "0" is latched as the background density to be obtained. The background detection is performed by the F / F403 as this register.
It is implemented by the CPU reading the value of 5 from the IPU bus.

8 and 9 are views for explaining the processing means and the input / output characteristics of the background removal 203b, and FIG. 10 is the storage means 10.
It is a figure explaining the content of 5.

Background removal 2 shown in FIGS. 8 (a) and 8 (b)
03b shows an example according to the conventional technique and an example according to the embodiment input of the present invention, both of which are implemented by the table conversion method. In the background removal 203b in the case of the prior art, as shown in FIG. 8A, the RGB signal level values Ri, Gi, Bi and the detection result value TH of the background detection 203a are input, and T
Select the table according to the H value, perform gamma conversion, and
The signal level values Ro, Go, and Bo of GB are output. This input / output relationship is shown in FIG. 9A, and it can be seen that only the highlight part is removed and the shadow part is reproduced as it is. The internal structure of the storage means 105 in the case of this conventional technique is shown in FIG.
CMYK image data is stored in the area in a frame-sequential manner.

Background Removal 203 for Embodiments of the Present Invention
As shown in FIG. 8B, b is each signal level value Ri, Gi, Bi of RGB, and the detection result value T of the background detection 203a.
H and signal LS are input, and by the table conversion method,
Select the table according to the TH value, perform gamma conversion,
The RGB signal level values Ro, Go, and Bo are output.
This input / output relationship is shown in FIG. 9 (b), and these are the same as in the case of the conventional technique described in FIG. 8 (a) and FIG. 9 (b). In the storage unit 105 according to the embodiment of the present invention, as shown in FIG.
The MYK image data is stored in a frame-sequential manner, and in the header portion of the image data memory, background removal notch information, show-through prevention notch information, and document background density information are additionally stored.

The embodiment of the present invention includes a background removing circuit on the CMYK processing side in addition to the background removing circuit on the RGB side as described above, and the input / output characteristics in the background processing on the CMYK processing side. Is shown in FIG. The background removing means may be the same as the processing on the RGB side.
In the example shown in (1), only the highlight is to be removed.

FIG. 12 shows the background removal 203 in the case of the prior art.
b, a block diagram showing the overall configuration of the storage means 105,
FIG. 13 is a block diagram showing the overall configuration of the background removal 203b and the storage means 105 in the embodiment of the present invention.

As can be seen from FIG. 12 and FIG. 13, in the case of the conventional technique shown in FIG.
It is performed only on the RGB side before being stored in 05. On the other hand, in the embodiment of the present invention, as shown in FIG. 13, in addition to the background removal 203b-1 on the RGB side, the background removal on the CMYK processing side is performed after the read data from the storage unit 105 is expanded. 203b-2 is added. Therefore, a CPU having the above-mentioned information added to the header of the storage unit 105 is required. The processing contents of this background removal 203b-2 are as shown in FIG.
(B), as described with reference to FIG. 11, and the content of the storage means is as described with reference to FIG. 10 (b).

Regarding the position where the background removing unit 203b-2 is provided, it is premised that it is performed after the read data from the storage unit 105 is expanded and before the printer gamma 207 and the gradation process 208. However, since the background removal function can be added to the printer gamma table in order to eliminate the hardware addition of the background removal circuit on the CMYK side, it is possible to provide the printer gamma table with the function of the background removal circuit on the CMYK side. Good.

FIG. 14 is a view for explaining the writing timing of the background density of the original which is the additional information of the accumulated data. To write image data, write to each plane while FGATE is valid and FGAT until the next FGATE is valid.
Timing signal C for writing additional information during E negation
This is performed by generating DEN and writing additional information in the header part.

FIG. 15 is a diagram for explaining an example of header information. In many cases, the background removal function and the show-through prevention function can be selected from several stages. Whether or not to use the background density of the original can be switched depending on whether the automatic density key is selected or not. Often done. Specifically, each header information is as follows: Background removal notch information: Background removal selection key ON / OF
F, background removal amount selection notch show-through prevention notch information ... Show-through prevention selection key ON /
OFF, show-through prevention selection Notch automatic density Notch information: Automatic density selection key ON / OF
F, the background density of the document.

The background removal processing according to the embodiment of the present invention is summarized as follows.

(1) Local storage (storage means 10
In the case of processing that does not use 5), the same RG as the conventional method is used.
The background removal processing on the B side is performed. When the background removal selection key is ON, the data on the highlight side is cut, but when the show-through prevention selection key is ON, a highlight removal curve for background removal and a highlight removal curve for show-through prevention are ORed. Is the actual amount of highlight removal. In this case, the additional information in the header becomes invalid, and the background removal on the CMYK side is turned off.

(2) Local storage (storage means 10
In the case of the process using 5), the background removal process on the RGB side is forcibly turned off, and the background removal process on the CMYK side is performed based on the additional information in the header.

Each processing according to the above-described embodiment of the present invention can be configured as a processing program, and the processing program is HD, DAT, FD, MO, DVD-.
It can be provided by being stored in a recording medium such as a ROM or a CD-ROM.

[0044]

As described above, according to the present invention, the background removal key information, the show-through prevention key information, and the document background density result are stored as additional information at the head of the storage memory means. Regardless of whether or not the memory is used, it is possible to maintain the print of the same image quality, and further, it is possible to perform the background removal according to the highlight characteristics of the printer.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a digital color copying machine using an image processing apparatus according to the present invention.

FIG. 2 is a diagram illustrating an internal configuration and a processing flow of an IPU 102 in FIG. 1 in the case of a conventional technique.

FIG. 3 is a simple block diagram illustrating a configuration of an operation unit 104 and a configuration of peripheral elements thereof.

FIG. 4 is a background detection & in the case of the prior art which is the basis of the present invention.
3 is a block diagram showing a detailed configuration of background removal 203. FIG.

5 is a diagram showing a configuration of a state machine in FIG.

6 is a diagram showing a configuration of a background density determination 403 in FIG. 4 in an embodiment of the present invention.

FIG. 7 is a time chart explaining a writing timing to a background density register.

FIG. 8 is a diagram illustrating a processing unit for background removal 203b.

FIG. 9 is a diagram illustrating the input / output characteristics of the background removal 203b.

FIG. 10 is a diagram illustrating the contents of a storage unit 105.

FIG. 11 is a diagram illustrating input / output characteristics in the background processing on the CMYK processing side.

FIG. 12 is a block diagram showing an overall configuration of a background removal 203b and a storage unit 105 in the case of a conventional technique.

FIG. 13 is a background removal 203b in the case of the embodiment of the present invention.
3 is a block diagram showing an overall configuration of a storage unit 105 and a storage unit 105. FIG.

FIG. 14 is a diagram for explaining a writing timing of a document background density which is additional information of accumulated data.

FIG. 15 is a diagram illustrating an example of header information.

[Explanation of symbols]

101 scanner 102 IPU 103 printer 104 Operation part 105 storage means 201 scanner gamma 202 Filtering 203 Background detection, background removal 204 color correction, UCR / UCA 205 compression 206 Stretch 207 Printer gamma 208 gradation processing 209 Image area separation 210 ACS 211 IPU side CPU 300 operation panel 301 Operation unit side CPU 401 state machine 402 Minimum value detection 403 Background density judgment

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5B057 BA02 CA01 CA02 CA08 CA12                       CA16 CB01 CB02 CB08 CB12                       CB16 CC01 CE02 CE11 CH08                 5C077 LL02 MP01 MP08 PP15 PP25                       PP44 PQ08 PQ12 PQ20 SS05                       TT06

Claims (6)

[Claims] 1. An image inputting means for reading a document, a means for detecting a highlight density of image data obtained by the image inputting means, and a first removing means for removing the highlight density of the read image data. An accumulation memory means for accumulating the image data from the removing means, a second removing means for re-reading the accumulated image data to remove the highlight density of the image data, and an image from the second removing means. An image processing apparatus having a means for printing data, a means for accumulating background removal amount designation key information and a result of a highlight density detecting means as additional information at the head of the accumulating memory means, and the accumulating memory means. And a means for switching between invalidating and validating the first removing means depending on whether or not to use the image data of Image processing apparatus. 2. The image processing apparatus according to claim 1, wherein the background removal key information is used as the background removal amount designation key information. 3. The show-through prevention key information is used as the background removal amount designation key information.
The image processing device described. 4. A document is read and input, the highlight density of the input image data is detected, the highlight density of the image data is removed, and subsequent image data is stored. In an image processing method of re-reading, removing the highlight density of the image data and printing the image data, in storing the image data, background removal amount designation key information and highlight density detection as additional information at the beginning thereof. The result is accumulated, and whether to remove or enable highlight removal before the accumulation of the image data is switched depending on whether to accumulate and use the image data. 5. The image processing method according to claim 4, wherein information of a background removal key or information of a show-through prevention key is used as the background removal amount designation key information. 6. A color copying machine comprising the image processing apparatus according to claim 1, 2, or 3.