JP4056275B2 - Image processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus applied to a digital full-color image processing apparatus with an automatic background removal function.
[0002]
[Prior art]
The background of the present invention will be described. Various methods for cutting the background density of a non-white original such as rough paper or newspaper have been considered.
[0003]
As a typical example, for example, an image processing apparatus described in JP-A-10-173874 has been known. This device detects the density of each pixel of the document during Bk imaging, which is the first scan, detects the background density by detecting the density peak, and performs background removal after the second scan, that is, during CMY version imaging. Is what you do. This is to create a full-color image, but with respect to a portion with a low density (hereinafter referred to as highlight) such as the background density, even if it is gray, it is not an image of one color of the Bk plate, This process assumes that development is performed at (hereinafter referred to as UCR is low).
[0004]
However, for newspaper manuscripts, yellow with the background density is noticeable around the character portion. Since the character portion is photograph-processed, problems such as blurring occur, and character processing that develops with Bk1 color on the highlight side (hereinafter referred to as high UCR) is desirable. That is, it is desired to remove the background density of the document even for Bk development.
[0005]
On the other hand, Japanese Patent Application Laid-Open No. 11-144047 discloses that when image data of a plurality of originals is stored in a memory called a local storage and data is shared via a network system, a copy condition is added to the image memory, and the image data A file system for calling additional information at the time of reading and creating a print image and a recording medium on which a program used for the system is recorded are described.
[0006]
However, even in this case, it is information such as copy conditions, date, administrator, etc., and it does not add additional information of the read original. Further, the removal amount of the background density may vary depending on the highlight characteristics of the printer (background dirt, dust, etc.). However, with the current background removal method, when image data is read into the local storage memory, the background removal has already been performed, and it has not been possible to cope with the case where it is desired to make use of the background density.
[0007]
[Problems to be solved by the invention]
Accordingly, in order to solve the above problems, the present invention provides an image processing apparatus provided with a background removal circuit corresponding to the printer characteristics without pre-scanning and almost no additional hardware when using a local storage memory. The purpose is to do.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, the image processing apparatus includes an image input unit that reads a document, a detection unit that detects a highlight density of image data obtained by the image input unit, and a detection result of the detection unit. , a storage prior highlight density removing means for removing the highlight density of the image data read by the image input means, memory means for storing the image data read, reads the stored the image data again , said a storage after highlight density removing means for removing the highlight density of the image data, and means for printing the image data processed by the storage before the highlight density removing means or the storage after the highlight density removing means, the accumulate the results of the highlight density detecting means as additional information to the head of the image data stored in the memory means Means that, depending on whether or not to use the image data of said memory means, or to remove the highlight density by the accumulated previous highlight density removing means, the highlight density by the accumulation after the highlight density removing means And control means for switching whether or not to remove .
[0009]
According to the second aspect of the present invention, the image processing apparatus includes an image input unit that reads a document, a detection unit that detects a highlight density of image data obtained by the image input unit, and a detection result of the detection unit. The highlight density removal means before accumulation for removing the highlight density in the RGB data read by the image input means, the color correction means for converting the RGB data into CMYK data, and the CMYK corrected by the color correction means memory means for storing data, said read memory means the stored the image data again, and storage after highlight density removing means for removing the highlight density in said read CMYK data, the accumulated before highlighting the image data processed by the concentration removing means or the storage after the highlight density removing means Means for lint, and means for storing the result of the highlight density detecting means as additional information to the head of the image data stored in said memory means, depending on whether or not to use the image data of said memory means, said And a control means for switching whether to remove the highlight density by the highlight density removal means before accumulation or to remove the highlight density by the highlight density removal means after accumulation .
[0010]
According to a third aspect of the present invention, when the image data of the memory means is not used , the control means is the image processing apparatus according to the first or second aspect, wherein the pre-accumulation highlight density removing means is used. It is what.
[0011]
According to a fourth aspect of the present invention, in the case of using the image data of the memory means , the control means is the image processing apparatus according to the first or second aspect, wherein the post-accumulation highlight density removing means is used. It is what.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an image processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0013]
FIG. 1 is a block diagram of a digital color copying machine as an embodiment of an image processing apparatus according to the present invention. The general flow of the image path is that the image data read from the scanner 101 is processed by the IPU 102 and output to the printer 103.
[0014]
The operation unit 104 has a function of notifying the scanner 101, the IPU 102, and the printer 103 of various settings. In the present invention, storage means 105 having an image memory of one frame or more called local storage is connected to the IPU 102. Even in a normal copy sequence, image data is exchanged via the storage means 105.
[0015]
FIG. 12 shows a connection diagram between the internal configuration of the conventional IPU 102 and the storage means 105. This figure is a block diagram of an electrical component of a conventional digital color copying machine. 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 a feature amount from the input image data, determines whether the original is a character area, a photographic area, or another area in real time, and outputs the determination result to each image processing block after the scanner gamma 201. Has a function to output.
[0016]
The scanner gamma 201 has a function of converting linear reflectance data from the scanner into density linear characteristics. After the scanner gamma 201 processing, filter processing 202, background detection / background removal 203, color correction / UCR / UCA 204, and compression 205 are sequentially executed, and image data is stored in the storage unit 105.
[0017]
In the filter process 202, according to the determination result of the image area separation, the edge emphasis process for MTF correction is executed in the character area, and the smooth process for halftone dot moiré prevention is executed in the photo area.
[0018]
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 by the scanner 101, and the background removal is executed according to the detected value. The color correction / UCR / UCA 204 performs complementary color conversion of RGB data to CMY data, calculates a Bk amount from the converted CMY data, and creates image data for four colors of CMYBk that is the basis of the print ink.
[0019]
The image data for four colors of CMYBk is stored in the storage means 105. If one document, for example, A3 size is 600 dpi, the capacity becomes 280 Mbytes. Therefore, image compression is performed by the compression circuit 205 and the memory capacity is increased. Reduction. For example, when 1/4 compression is performed, the total capacity is 70 Mbytes.
[0020]
The image data read from the storage unit 105 sequentially flows to the expansion circuit 206, the printer gamma 207, and the gradation processing 208. As image paths, there are a case in which CMYK four colors are read simultaneously, a case in which only one color is read out, and two cases.
[0021]
The decompression circuit 206 is a circuit that decompresses the data compressed by the compression circuit 205, and the printer gamma 207 performs reverse correction of the printer main body characteristics and the gradation processing gamma characteristics so that the output sample is linear in density. . In the gradation processing 208, according to the determination result of the image area separation, gradation processing emphasizing resolution is executed in the character area, and gradation processing emphasizing gradation is executed in the photograph area.
[0022]
In parallel with the scanner gamma 201 and the image area separation 209, there is a process called ACS 210, which is unique to a one-drum machine, and determines whether the read original is a color original or a black and white original. Is to perform only Bk development and print out.
[0023]
FIG. 2 shows a simple block diagram in which the IPU 102 and the operation unit 104 are picked up in an embodiment of the image processing apparatus according to the present invention. Each process in the IPU 102 is connected by a single IPU bus, and various parameters can be set by the CPU. Various parameter settings are selected by the operation unit 104 as actual parameter settings, and the values are set by performing serial communication between the CPU 301 of the operation unit 104 and the CPU 211 of the IPU 102.
[0024]
Next, FIG. 13 shows a detailed block diagram of conventional background detection / background removal 203 on which the present invention is based. This figure is a block diagram of color automatic background removal as a prior art. The background detection unit 203a includes a state machine 401, a minimum value detection 402, and a background density determination 403. The background density determination 403 has a background density register in the background density determination 403, and detects one background density for one document. Become.
[0025]
FIG. 3 shows an example of the state machine 401. This figure shows a GATE signal input to the state machine 401 in the background detection unit 203a in the embodiment of the image processing apparatus according to the present invention. This indicates an effective period in which the background density determination is performed, and the effective period is indicated by the AND condition of the effective area LGATE in the main scanning direction and the effective area FGATE in the sub-scanning direction. Note that the minimum value detection 402 is a function that only detects and outputs the minimum value from the input RGB data, and therefore the details are omitted.
[0026]
FIG. 4 shows an example of the background density determination 403. This figure is a block diagram showing background density determination in the background detection unit 203a in the embodiment of the image processing apparatus according to the present invention. There are two types of F / F, the tmp register and this register. The tmp register has a function of updating the brightest (minimum value) point in the effective area in units of pixel clocks. This register is updated in the effective area together with the tmp register, but is latched as the background density for obtaining the value of the tmp register at the point where the effective area is closed (negated). Background detection is performed by the CPU reading this register through the IPU bus system.
[0027]
FIG. 5 shows the timing of writing to the background density register. This figure is a timing chart of the background detection unit 203a in the embodiment of the image processing apparatus according to the present invention.
[0028]
14, FIG. 15, and FIG. 16 show the contents of the background removal unit 203b and the accumulating unit 105 up to now. Offset subtraction is performed according to the detection result of the background detection unit 203a. An example is shown in FIG. 14 and FIG. There are several types of background removal calculation methods, but in this example, only the highlight portion is removed and the shadow side is reproduced as it is. Since the CMYK image memory is stored as the storage means, data is stored in the frame order (see FIG. 16).
[0029]
6, FIG. 7, FIG. 8, and FIG. 9 show the contents of the background removal unit 203b and the storage means 105 in the image processing apparatus according to the present invention. FIG. 6 and FIG. 7 showing the background removal circuit on the RGB side are the same as FIG. 14 and FIG. 15 in the conventional example. Storage means In FIG. 8, the background detection density is attached as additional information to the header portion of the image data memory. In FIG. 8, the number of bytes of the header is not specified, but since the background density detection of only one color is currently performed, the header is one byte. In addition, background removal means on the RGB side is required on the CMYK processing side. The background removal method may be the same as the processing on the RGB side, and an example is shown in FIG. FIG. 9 shows a background removal circuit in an embodiment of the image processing apparatus according to the present invention.
[0030]
FIG. 10 shows a configuration diagram in which the background removal means on the RGB side is directly held on the CMYK side. This figure is a part of a block diagram of an electrical component of a digital color copying machine which is an embodiment of an image processing apparatus according to the present invention. The position of the background removing unit is premised on that the data read from the storage unit 105 is expanded and then performed before the printer gamma 207 and the gradation processing 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, the present invention has a great influence even if the background removal circuit on the CMYK side is not provided. There is no.
[0031]
FIG. 11 shows the timing of writing the document background density, which is additional information of the accumulated data. This figure shows the additional condition write timing to the storage memory in the embodiment of the image processing apparatus according to the present invention. When writing image data, each plane is written while FGATE is valid, a timing signal CDEN for writing additional information is generated during the FGATE negation until the next FGATE is valid, and written in the header portion.
[0032]
The background removal processing in the present invention is summarized as follows.
(1) In the case of processing not using the local storage (accumulating means 105) The same background removal processing on the RGB side as the conventional method is performed, the additional information of the header becomes invalid, and the background removal on the CMYK side is turned off.
(2) In the case of processing using local storage (storage means 105), the background removal processing on the RGB side is forcibly turned off, and the background removal processing on the CMYK side is performed based on the additional information of the header.
[0033]
【The invention's effect】
According to the first to fourth aspects of the present invention, the result of the highlight density detecting means is accumulated as additional information at the head of the image data accumulated in the memory means, so that the background removal is matched with the highlight characteristic of the printer. Can be done. For this reason, it is possible to suppress highlight skipping and the like due to extra background removal. Further, the result of the highlight density detecting means can be reflected from the first color of the print. Therefore, it is possible to remove the background appropriately for any development color, and to improve the print quality.
[0034]
According to the first to fourth aspects of the present invention, the result of the highlight density detecting means is accumulated as additional information at the head of the image data accumulated in the memory means, and the background removal circuit is provided before and after the memory means. The background removal processing can be performed in accordance with the highlight characteristics of the printer. Further, the result of the highlight density detecting means can be reflected from the first color of the print.
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital color copying machine as an embodiment of an image processing apparatus according to the present invention.
FIG. 2 is a block diagram picking up elements of an image processing apparatus according to an embodiment of the present invention and its periphery from FIG.
FIG. 3 is an explanatory diagram showing a GATE signal input to the state machine in the background detection unit in the embodiment of the image processing apparatus according to the present invention.
FIG. 4 is a block diagram showing background density determination in a background detection unit in an embodiment of the image processing apparatus according to the present invention.
FIG. 5 is a diagram showing a timing chart of a background detection unit in an embodiment of the image processing apparatus according to the present invention.
FIG. 6 is an explanatory diagram of a background removal circuit in an embodiment of an image processing apparatus according to the present invention.
FIG. 7 is an explanatory diagram of a background removal circuit in an embodiment of an image processing apparatus according to the present invention.
FIG. 8 is an explanatory diagram of a storage memory in an embodiment of an image processing apparatus according to the present invention.
FIG. 9 is an explanatory diagram of a background removal circuit in an embodiment of an image processing apparatus according to the present invention.
FIG. 10 is a part of a block diagram of an electrical unit of a digital color copying machine as an embodiment of an image processing apparatus according to the present invention.
FIG. 11 is an explanatory diagram showing additional condition write timing to the storage memory in the embodiment of the image processing apparatus according to the present invention;
FIG. 12 is a block diagram of an electrical component of a digital color copying machine as a prior art.
FIG. 13 is a configuration diagram of automatic color background removal as a prior art.
FIG. 14 is an explanatory diagram of a background removal circuit as a conventional technique.
FIG. 15 is an explanatory diagram of a background removal circuit as a conventional technique.
FIG. 16 is an explanatory diagram of a storage memory as a conventional technique.
[Explanation of symbols]
101 Scanner 102 IPU
DESCRIPTION OF SYMBOLS 103 Printer 104 Operation part 105 Accumulation means 201 Scanner gamma 202 Filter process 203 Background detection / background removal 203a Background detection part 203b Background removal part 204 Color correction / UCR / UCA
205 Compression Circuit 206 Expansion Circuit 207 Printer Gamma 208 Gradation Processing 209 Image Area Separation 210 ACS
300 Operation unit 401 State machine 402 Minimum value detection 403 Background density determination

Claims (4)

Image input means for reading a document;
Detection means for detecting a highlight density of image data obtained by the image input means;
According to the detection result by the detecting means, and storage prior to highlight density removing means for removing the highlight density of the image data read by the image input means,
Memory means for storing the read image data;
A post-accumulation highlight density removal unit that reads the stored image data again and removes the highlight density of the image data;
Means for printing the image data processed by the highlight density removal means before accumulation or the highlight density removal means after accumulation ;
Means for accumulating the result of the highlight density detection means as additional information at the head of the image data accumulated in the memory means ;
Whether the highlight density is removed by the highlight density removal means before accumulation or the highlight density is removed by the highlight density removal means after accumulation depending on whether or not the image data of the memory means is used . And an image processing apparatus. Image input means for reading a document;
Detection means for detecting a highlight density of image data obtained by the image input means;
A pre-accumulation highlight density removing means for removing the highlight density in the RGB data read by the image input means according to the detection result by the detection means ,
Color correction means for converting the RGB data into CMYK data;
Memory means for storing CMYK data corrected by the color correction means ;
A post-accumulation highlight density removal unit that reads the image data stored in the memory unit again and removes the highlight density in the read CMYK data ;
Means for printing the image data processed by the highlight density removal means before accumulation or the highlight density removal means after accumulation ;
Means for accumulating the result of the highlight density detection means as additional information at the head of the image data accumulated in the memory means ;
Whether the highlight density is removed by the highlight density removal means before accumulation or the highlight density is removed by the highlight density removal means after accumulation depending on whether or not the image data of the memory means is used . And an image processing apparatus. 3. The image processing apparatus according to claim 1 , wherein when the image data of the memory means is not used , the control means uses the pre-accumulation highlight density removing means . 3. The image processing apparatus according to claim 1 , wherein when the image data of the memory means is used , the control means uses the post-accumulation highlight density removing means .

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