JPH11164164A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply ROP-processed data to a printer for performing printing corresponding to CMYK data. SOLUTION: A color conversion part 50 is not provided with UCR and BG processing parts, while a data correction part 9 detects black density of an area under consideration of binary CYM color data outputted from a binarization processing part 7. Then, a BG/UCR pattern is generated based on the detected density, and CMYK color printing data are generated through the pattern. That is, an ROP processing can be coped by carrying out UCR and BG processings to the binary CYM color data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus, and more particularly to a color image processing apparatus that outputs a color image signal based on drawing data specified in a page description language.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, drawing data received from a host computer is converted into cyan (C), yellow (Y), magenta (M), and black (K). In some cases, the image is converted into CMYK data corresponding to the toner color and output to a printer engine, that is, an image output terminal (IOT), to obtain a color image.

FIG. 12 is a block diagram showing an example of a conventional color image forming apparatus. Referring to FIG. 1, drawing data supplied from a host computer 1 is input to an image processing device (controller) 2, and after performing scheduled image processing, is output to an IOT 3 to obtain a color image. The host computer 1 has an RG described in a printer description language (PDL) represented by PostScript (PostScript).
Outputs drawing data in the B color space. The interface control unit 4 of the controller 2 receives the drawing data, that is, the RGB data, and transfers it to the PDL interpretation unit 5. PDL typically composed of a PostScript interpreter
The interpretation unit 5 interprets the RGB data, converts the RGB data into CMYK data, and outputs the data to the drawing unit 6. The drawing unit 6 performs an AND operation on the CMYK data input from the PDL interpreting unit 5 according to the instruction content included in the drawing data.
It performs processing and OR processing, and outputs the result to the binarization processing unit 7. The binarization processing unit 7 outputs the CM expressed by 8 bits.
The YK data is binarized and output to the drawing memory 8.
When the binarized data for one page is accumulated, for example, the drawing memory 8 sequentially outputs the binarized data to the IOT 3.

[0004] The PDL interpreter 5 has a color converter 50. The color conversion unit 50 includes a signal conversion unit 500 that converts the supplied RGB data into CMY data, and an under color removal (UCR) of the CMY data obtained by the signal conversion unit 500.
Signal corrector 50 that performs processing and black generation (BG) processing
1 is included.

[0005] In the black generation processing in the signal correction unit 501, for example, an equal amount is removed from each component of the CMY data, and black (K) is generated based on the removed CMY data. In the undercolor removal process, for example, an equal amount is removed from each component of the CMY data to generate black. Since an equal component is removed from each of the CMY data by the under color removal processing, there is an effect of suppressing wasteful consumption of toner. The under color removal processing and the black generation processing are performed using a BG function and a UCR function, respectively.

As a color image forming apparatus having an undercolor removal processing means, for example, a color image forming apparatus described in Japanese Patent Publication No. 7-36609 is known.

[0007]

The color image forming apparatus shown in FIG. 12 has the following problems. In recent years, GDI (Gr.
2. Description of the Related Art A printer with a simplified function that performs drawing based on an aphical display interface has been known. A printer that performs drawing based on GDI needs to have a function called a raster operation (ROP process). The ROP process has a feature that various image processes can be performed because the calculation method of the process in the drawing unit can be selected.

This ROP processing is performed for RGB data or CM data.
Can be performed on Y data, and CMY
When processing is performed on CMYK data generated based on data, a desired processing result may not be obtained. However, as described above, conventionally, data input to the drawing unit 6 has been converted into CMYK data.
Therefore, when realizing the function of the ROP processing in the drawing unit 6, it is necessary to input drawing data to the drawing unit 6 in the form of CMY data (or RGB data).

When the IOT is configured to output an image based on CMYK data,
It is necessary to generate black (K) from MY data. However, based on the CMY data after the ROP processing,
There is a problem that a desired color cannot be obtained simply by replacing the point where the CMY components overlap with black (K).

An object of the present invention is to solve the above-mentioned problems and to provide an image processing apparatus capable of outputting CMYK data to an IOT while enabling ROP processing requiring CMY data as input data. I do.

[0011]

SUMMARY OF THE INVENTION The present invention relates to an image processing apparatus for generating CMYK color print data from CMY color print data.
A binarization unit for converting into YM color data, a density determination unit for detecting a black density of a region of interest of the binary CYM color data output from the binarization unit, BG / UCR scheduled based on
Pattern generating means for selecting a pattern, wherein CMYK color print data is generated based on the pattern selected by the pattern generating means.

According to the above feature, the density information of the target area of the binarized CYM color data is used as information for generating a BG / UCR pattern.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a color image forming apparatus to which the image processing apparatus of the present invention is applied, and the same reference numerals as those in FIG. In FIG. 1, the color conversion unit 50 of the PDL interpretation unit 5 includes a data conversion unit 500 that converts input RGB data into CMY data.
There is no function equivalent to. Therefore, data input from the PDL interpretation unit 5 to the drawing unit 6 is CMY data that has not been subjected to undercolor removal or black generation processing.

Since the input data is CMY data, the rendering unit 6
OP processing can be performed. The drawing unit 6 performs arithmetic processing on the CMY data according to the instruction, and the processed data is 2
It is input to the value processing unit 7. The binarization processing unit 7 converts the input data into 1-bit binary data, and inputs the binary data to the data correction unit 9. The data correction section 9 performs under color removal processing and black generation processing on the binarized CMY data and inputs the processed CMY data to the drawing memory 8.

Next, the processing of the data correction section 9 will be described. FIG. 2 is a flowchart showing a processing procedure of the data correction processing unit 9, and FIG. 3 is a schematic diagram of a region of interest showing a result of the processing. First, in step S1, logical black data K is generated by performing an AND process on the CMY data of the region of interest in FIG. 3A, that is, the 8 × 8 region (FIG.
(B)). In step S2, the number m of black dots in the black data is counted. In step S3, the number m of black dots is converted into multi-level data of 256 gradations. The equation used for this level conversion is “m / 64 × 256”. The value calculated by this equation is used as the input value of the black generation processing and the undercolor removal processing, that is, the black density value k. For example, FIG.
If the number m of black dots is “16” as shown in FIG.
/ 64 × 256 = 64 ”, and the black density value k is“ 64 ”
It is.

In step S4, a function BG of black color generation processing is calculated for the density value k, and a calculation result bg is obtained. In step S5, similarly, a correction value ucr is obtained by calculating the function UCR of the under color removal processing for the density value k. Here, the functions BG (k) and UCR (k) are 0.5
(K) and the density value k is set to be 50%, so that the calculation result, that is, the correction values bg and ucr are “3”.
2 ". The functions BG and UCR are not limited to these values, and can be selected from preset values according to the type of image to be output and desired image quality.

In step S6, a pattern corresponding to the value of the correction value bg is selected from preset patterns to obtain black n × n (8 × 8) data K ′. The obtained data of K ′ is shown in FIG.

In step S7, a pattern ucr corresponding to the value of the correction value ucr is determined from a preset pattern.
Select ptn. An example of the selected pattern ucrptn is shown in FIG. In step S8, the pattern u
An AND of the crptn and each component of the CMY data is calculated, and n × n data C ′, M ′, Y ′ of C, M, and Y are obtained.
Get. The processing result of step S8 is shown in FIG.

In the above flowchart, the calculation of the density value k and the calculation of C ', M', Y ', K' are performed by the following equations. k = min (C, M, Y) = C & M
& Y, C '= C-UCR (k) = C & UCR (k), M
'= M-UCR (k) = M & UCR (k), Y' = Y-
UCR (k) = Y & UCR (k), K ′ = BG (k).

Next, a second embodiment of the present invention will be described.
The following problems occur when drawing a black font on a white background. FIG. 4 is a diagram showing a process in a case where a font edge is applied to a region of interest. Here, a 4 × 4 area is taken as an example. As shown in FIG.
Is applied, the density value k is “64”, that is, “4 /
16 × 256 ”. Here, assuming that the functions BG (k) and UCR (k) are both set to 1.0 (k), that is, the density value k is set to 100%, C ′, M ′,
Y ′ is “0” and K ′ is “64”. That is, the font portion is not completely black.

In the screen pattern shown in FIG. 5, the density "64" in FIG.
When the value is converted, only the four dots at the center of the target area become “1”, that is, black (see FIG. 6), and the edge E of the font is shifted from the original position. When a font is drawn with such dots, the characters are not sharp and lack sharpness.

Therefore, in the second embodiment, the data correction section 9 is provided with an image recognizing means to solve the above problem. FIG. 7 is a flowchart of a main part of the second embodiment. In step S10, the value D obtained by AND processing the CMY data
1 is compared with a value D2 obtained by performing an OR process on the CMY data. In step S11, it is determined whether the values D1 and D2 are the same value. If this determination is affirmative, it is determined that the components of the CMY data have the same value, and the process proceeds to step S12, where C ′, M ′, and Y ′ are all set to “0”,
K ′ outputs the AND processing result of the CMY data as it is so that the black dot portion can be printed without changing its position. That is, the pattern of FIG. 4 is maintained.

On the other hand, if the determination in step S11 is negative, it is determined that the black character portion does not cover the area of interest, and the flow advances to step S13, where C 'and M' are normally performed according to the functions BG and UCR. , Y ′, K ′ are calculated.

As described above, the image recognition means recognizes the black character portion of the region of interest, and when it is determined that the character portion is the black character portion, the data of the character portion can be retained and the data can be output.

Next, a third embodiment of the present invention will be described.
In the above-described embodiment, the black generation processing and the background removal processing are performed using the density information of black (K). In the third embodiment, the black generation processing and the background removal processing are performed using the CMY density information. FIG. 8 is a diagram showing each component of CMY data of an image to be processed by the data correction unit 9 according to the third embodiment. As understood from FIG.
At × 4, the value of the Y component is “4”, the value of the M component is “8”, and the value of the C component is “16”. When the value of each color component of this region of interest is converted into multi-level data of 256 gradations,
The value of the Y component is “64”, the value of the M component is “128”, and the value of the C component is “191”.

The multi-value data is subjected to black generation processing and background removal processing. For example, the common portion “64” of each component of the CMY data is removed from each color component, and the common portion “64” is set as a black component K ′. That is, Y '
Is "0", M 'is "64", C' is "191", and K 'is "64". This value is binarized in a predetermined pattern. FIG. 9 is a diagram showing the components of C ', M', Y ', and K' after the black generation processing and the background removal processing.

It is needless to say that the third embodiment can be modified so that the image recognizing means determines the presence or absence of a black character as in the second embodiment.

Next, the main functions of the processing in the first and third embodiments will be described with reference to block diagrams. FIG.
0 is a main part functional block diagram of the first embodiment. In FIG. 1, the density determination unit 10 determines the AN of each component of the CMY data.
By taking D, logical black data K representing the density of the region of interest is generated. The BG correction value calculation unit 11 calculates the input black data K using a function BG to obtain a black density correction value bg. The BG pattern generator 12 outputs a dot pattern corresponding to the density correction value bg as black data K '.

On the other hand, the UCR correction value calculation section 13 calculates the black data K by a function UCR to obtain a density correction value ucr of the CMY data. The UCR pattern generation section 14 outputs a dot pattern ucrptn corresponding to ucr as the density correction value. The logical operation unit 15 performs an AND operation on the original CMY data and the dot pattern ucrptn to obtain the data C.
', M', and Y '.

FIG. 11 is a functional block diagram of a main part of the third embodiment. In the figure, a density determination unit 16 detects the density of each component of the CMY data and generates logical CMY data. The BG operation unit 17 receives the input CMY
The multi-valued black data K 'is calculated from the data. For example, C
The AND of each component of the MY data is calculated. The BG pattern generating unit 18 generates a black scheduled pattern based on the multi-valued black data K '. For example, when the binarization pattern is selected, the black data K 'is binarized.

On the other hand, the UCR operation unit 19 outputs a logical CM
Multi-value data C ', M', Y
Ask for '. For example, a common part is removed from each color component.
The UCR pattern generator 20 generates multi-valued color data C ', M
A predetermined pattern is generated based on ', Y'. For example, when a binarization pattern is selected, cyan, magenta, and yellow data C ', M', and Y 'are binarized.

In the above embodiment, an 8 × 8 or 4 × 4 region of interest is assumed, but the size of the region of interest is not limited to this. However, it is most reasonable to pay attention to the screen matrix size of the binarization processing unit. This is because the CMY data binarized by the screen matrix is input to the data correction unit 9.

[0033]

As is apparent from the above description, according to the present invention, the density information of the target area of the binarized CYM color data can be used as the information for generating the BG / UCR pattern. Therefore, even when data is supplied to an output device that executes print processing in accordance with CMYK data, drawing processing can be performed on RGB or CMY data, for example, as in Windows ROP processing.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating processing of a data correction unit of the image processing apparatus according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of a region of interest after black generation processing and undercolor removal processing;

FIG. 4 is a schematic diagram of a region of interest including a character font portion.

FIG. 5 is a diagram showing an example of a screen matrix.

FIG. 6 is a diagram showing a binarized image that has passed through a screen matrix.

FIG. 7 is a flowchart of image recognition.

FIG. 8 is a diagram showing a binary image of CMY color data.

FIG. 9: CM after black generation processing and under color removal processing
FIG. 4 is a diagram illustrating a binary image of Y color data.

FIG. 10 is a functional block diagram of a main part of the image processing apparatus according to the first embodiment.

FIG. 11 is a functional block diagram of a main part of an image processing apparatus according to a third embodiment.

FIG. 12 is a block diagram illustrating a configuration of a conventional image processing apparatus.

[Explanation of symbols]

1. Host computer 2. Image processing device 3.
IOT, 5 ... PDL interpreter, 7 ... Binarization processor,
9: Data correction unit, 50: Color conversion unit

Claims (5)

[Claims] 1. An image processing apparatus for generating CMYK color print data from CMY color print data, comprising: binarizing means for converting multi-valued CMY color data into binary CYM color data; Density determining means for detecting a black density of a region of interest of the binary CYM color data, and pattern generating means for selecting a scheduled BG / UCR pattern based on the density detected by the density determining means, An image processing apparatus configured to generate CMYK color print data based on a pattern selected by a pattern generation unit. 2. An image processing apparatus for generating CMYK color print data from CMY color print data, comprising: binarizing means for converting multi-valued CMY color data into binary CYM color data; Density determining means for detecting the cyan, magenta, and yellow densities of the region of interest of the binary CYM color data, and pattern generating means for selecting a scheduled BG / UCR pattern based on the density detected by the density determining means. An image processing apparatus, comprising: generating CMYK color print data according to a pattern selected by the pattern generating unit. 3. An image recognizing means for recognizing an image in the area of interest, wherein when the image in the area of interest is recognized as a character portion, the pattern generating means 3. The image processing apparatus according to claim 1, wherein the data of the character portion is output without being changed. 4. The character recognition unit according to claim 3, wherein the image recognition unit determines that the character portion is present when a logical sum and a logical product of cyan, magenta, and yellow densities of the attention area are the same. Image processing device. 5. The image processing apparatus according to claim 1, wherein the region of interest has the same size as a screen matrix size of the binarizing unit.