JP2001160906A - Color image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image processor that accurately conducts a ROP processing and can output a color image, where black characters and thin lines are excellently reproduced satisfactorily. SOLUTION: A PDL analysis section 11 analyzes received PDL data and generates CMY intermediate information. A CMY image drawing processing section 12 applies CMY image drawing processing to the intermediate information. Furthermore, a K-image drawing processing 13 applies image drawing processing to the intermediate information, only when the CMY indicates 'black' and also applies ROP processing thereto as one of image drawing processing procedures. A conversion section 14 leaves the image drawing result of K and deletes the image drawing result of CMY, only when the CMY is 'black' or when is 'black', on the basis of the image drawing result of CMYK by the CMY image drawing processing section 12 and the K image drawing processing 13. In other cases, the conversion section 14 deletes the image drawing result of K and leaves the image drawing result of CMY. Thus, the conversion section 14 generates color output data in CMYK.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus for generating four color output data of three colors and a specific color from three color data.

[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 divided into cyan (C), yellow (Y), magenta (M) and black (K). Convert to CMYK data corresponding to toner color and output to printer engine,
There is one that obtains a color image. The host computer is, for example, a postscript (PostScript).
pt: registered trademark), a printer description language (PD)
L) in the RGB color space (hereinafter referred to as P
DL data). P of this RGB color space
The DL data is sequentially analyzed, subjected to black plate generation / under color removal processing and the like, converted into CMYK data, and output to, for example, a printer engine to obtain a color image. As a color image forming apparatus having an undercolor removal processing means, for example,
The thing described in 36609 gazette is known.

In recent years, printers for Windows (registered trademark) have been using GDI (Graphic).
2. Description of the Related Art There has been known a printer having a simplified function by performing drawing based on a cal display interface (cal Display Interface). In a printer that performs drawing based on GDI, raster operation (ROP)
It is necessary to have a function called processing. Various image processing can be performed by the ROP processing. For example, in Japanese Patent Application Laid-Open No. 8-156346, ROP
There is a description about processing.

[0004] This ROP processing is performed for RGB data or C data.
This can be performed on MY data,
When processing is performed on CMYK data generated based on Y data, a desired processing result may not be obtained. Therefore, ROP processing is performed in the RGB color space or CM
This must be done in the Y color space. Then, after the data in the RGB color space or the CMY color space, the CM
Conversion to data in the YK color space must be performed.

FIG. 7 is a block diagram showing an example of a conventional color image processing apparatus. In the figure, 1 is a PDL analysis unit, 2
Denotes a CMY drawing processing unit, and 3 denotes a conversion unit. Due to the necessity as described above, the conventional color image processing apparatus is, for example, shown in FIG.
The configuration shown in FIG.

For example, PDL data supplied from a host computer or the like is transferred to a PDL analyzer 1. PD
The L analysis unit 1 analyzes PDL data in the RGB color space,
For example, intermediate information suitable for drawing processing such as a display list is generated and stored. The CMY drawing processing unit 2
An actual drawing process is performed based on the intermediate information generated by the L analysis unit 1. In this drawing process, the above-described ROP process and the like are also performed. The conversion unit 3 uses the C, M, and Y drawing information generated by the drawing processing in the CMY drawing processing unit 2 based on the drawing information.
By performing black plate generation / under color removal processing, K drawing information is generated and output as data in the CMYK color space.

According to such a conventional color image processing apparatus, since the ROP processing is performed on the data in the CMY color space, an image on which the ROP processing has been accurately performed can be obtained. However, there is a problem that a desired hue cannot be obtained simply by replacing the point where the CMY components overlap with black (K) based on the data in the CMY color space after the ROP processing.

In order to solve such a problem, for example, as described in JP-A-11-164164, data in a CMY color space is binarized (screened) for each color, K density is determined for each predetermined area for the CMY data of
Data in the CMYK color space is generated. As a result, the data in the CMY color space after the ROP processing can be converted into the data in the CMYK color space while suppressing a change in color.

However, according to the method described in this document, the density is determined for each predetermined area. Therefore, for example, a thin line such as a black character or a ruled line on a colored background is not accurate. There was a problem that the density could not be determined and the image was not completely black.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables a color image capable of accurately performing ROP processing and capable of reproducing black characters and fine lines satisfactorily. It is an object of the present invention to provide a color image processing apparatus capable of outputting a color image.

[0011]

The present invention relates to, for example, CMY
In the color image processing apparatus for generating four color output data consisting of three colors and a specific color, for example, CMYK with K added, from the three color data of In addition to performing drawing in a color, in parallel with the drawing, drawing in a specific color is performed by a specific color drawing processing unit. Then, the conversion means generates four color output data of three colors and the specific color from the drawing result of the three colors by the three-color drawing processing means and the drawing result of the specific color by the specific color drawing processing means. It is a feature.
Thereby, for example, the drawing process such as the ROP process is favorably performed by the three-color drawing processing unit. On the other hand, for example, characters and thin lines are obtained as a specific color drawing result by the specific color drawing processing means. By generating four color output data from the three color drawing results and the specific color drawing result, The four-color output data in which characters and thin lines are also stored.

For example, similarly to the above-mentioned Japanese Patent Application Laid-Open No. H11-164164, the same processing can be performed in the case where binarization is performed by binarizing means after drawing processing such as ROP processing. When all the drawing results of the specific color are data to be drawn (for example, “1”), the binarized drawing result of the specific color is set as color output data of the specific color (for example, set to “1”). The three color output data are erased (for example, set to '0'). In other cases, the drawing result of the specific color is not used as color output data (for example, “0”), and the binarized drawing result of three colors is used as it is as three color output data. By generating the four color output data in this way, characters, thin lines, and the like can be stored in the specific color output data.

[0013]

FIG. 1 is a block diagram showing an embodiment of a color image processing apparatus according to the present invention. In the figure, 1
1 is a PDL analysis unit, 12 is a CMY drawing processing unit, and 13 is K
The drawing processing unit 14 is a conversion unit. Here, C, M,
The case of outputting color output data of three colors of Y and K as a specific color will be described.

The PDL analysis unit 11 analyzes PDL data supplied from, for example, a host computer or the like, and generates intermediate information in a CMY color space suitable for drawing processing such as a display list. The generated intermediate information is CM
It is passed to both the Y drawing processing unit 12 and the K drawing processing unit 13.

The CMY drawing processing unit 12 performs a drawing process on each of the C, M, and Y planes based on intermediate information in the CMY color space. ROP processing is also performed as one of the drawing processing. Since the ROP processing is performed in the CMY color space, the processing can be performed without any inconvenience.

The K drawing processing unit 13 performs the same drawing processing as the CMY drawing processing unit 13 only when C, M, and Y indicate “black” based on the intermediate information in the CMY color space.
For example, when C, M, and Y take values from 0 to 255, C = M
Only when = Y = 255, the drawing process is performed. As a result, black characters, fine lines, and the like can be drawn on the K plane. Note that, even when C, M, and Y indicate gray, the drawing process may be performed.

The conversion unit 14 draws a drawing result of each of the C, M, and Y planes that has been drawn by the CMY drawing processing unit 12,
The CMYK color output data is generated based on the drawing result of the K plane that has been subjected to the drawing processing by the K drawing processing unit 13. At this time, only when C, M, and Y indicate “black” and K indicates “black”, the drawing result is left on the K plane and the drawing result of each of the C, M, and Y planes is erased.
In other cases, the drawing result of the K plane is deleted,
The drawing result of each plane of C, M, and Y is left as it is. In this way, CMYK color output data is generated.

FIG. 2 is a flowchart showing an example of the processing of the conversion unit 14 in the embodiment of the color image processing apparatus of the present invention. Here, it is assumed that, for example, C, M, Y, and K take values from 0 to 255. In S21, an unprocessed pixel is selected, and a value is extracted from each of the C, M, Y, and K planes for the same pixel. In S22, C = M
= Y = K = 255. C = M = Y = K =
In the case of 255, in S23, K = 255 is left, and C = M = Y = 0 and erased. Also,
If not C = M = Y = K = 255, in S24, K = 0 and C, M, and Y are left as they are. In S25, it is determined whether or not the processing has been completed for all the pixels. If any unprocessed pixels remain, the process returns to S21 to perform the processing on those pixels.

When the processing is completed for all the pixels,
CMYK color output data is generated. In the K plane of the color output data, a portion expressed as “black”, for example, a black solid portion, a black character or a thin line is separated. For this reason, if the black portion of the K plane is preserved in the subsequent processing, it is possible to satisfactorily reproduce black characters and thin line portions whose image quality has been deteriorated in the past.

The multi-valued color output data generated as described above may be further subjected to black plate generation / under color removal processing. For example, Japanese Patent Application Laid-Open No.
It is also possible to use the technology described in Japanese Patent Application Publication No. 4 and Japanese Patent Application No. 11-150764.

FIGS. 3 and 4 are explanatory diagrams of an example of an image before and after the processing in the conversion unit 14. FIG. In the example shown in FIG. 3, as shown in FIG. 3A, the character “E” is drawn on the C and M planes by the CMY drawing processing unit 12, and the entire Y plane is filled with the Y color. I have. Also,
The character “E” is also drawn on the K plane by the K drawing processing unit 13. In such a case, the character "E" is drawn on any of the C, M, Y, and K planes, and the character "E" on the K plane is stored as it is, and the C, M, and In the Y plane, the character "E" is deleted. For the background portion other than the character 'E', the values of C, M, and Y are output as they are. As a result, as shown in FIG.
The character "E" is deleted from the C and M planes, and the character "E" is omitted from the Y plane. For the K plane, the character 'E' remains as it is.

In this manner, CMYK color output data in which the character 'E' is separated into K planes is generated. For example, when these are reproduced by a printer engine or the like, as shown in FIG. 3C, an image in which a black character 'E' is drawn on a yellow background is obtained. At this time, the character 'E' separated into the K color output data is reproduced by a black color material, so that it is reproduced with good image quality.

On the other hand, in some cases, such as when a black mask or the like is used in the ROP process, a black area may be present in the K drawing result by the K drawing processing unit 13 even for a portion other than black. is there. FIG. 4 shows an example of such a case. In this example, as shown in FIG. 4A, the character "E" is drawn on the C and M planes by the CMY drawing processing unit 12, and the Y plane is missing the character "E" and has a background. It is filled. Also,
The character “E” is also drawn on the K plane by the K drawing processing unit 13. In such a case, the character "E" is drawn on the C, M, and K planes, but not drawn on the Y plane.
In such a case, the character "E" portion of the K plane is deleted, and the drawing results of the C, M, and Y planes are held as they are. As a result, as shown in FIG.
The M and Y planes remain as they are, and the K plane has the character "E" erased. When the CMYK color output data generated in this way is reproduced by, for example, a printer engine or the like, as shown in FIG. 4C, an image in which blue characters 'E' are drawn on a yellow background is obtained.

In this way, it is possible to prevent the harmful effects of performing the drawing process only on black in the K drawing processing unit 13, and for example, in the example shown in FIG. 4, it is possible to prevent blue characters from becoming black.

FIG. 5 is a block diagram showing another embodiment of the color image processing apparatus of the present invention. In the figure, the same parts as those in FIG. Reference numeral 15 denotes a binarizing unit. The binarization unit 15 includes the CMY drawing processing unit 1
2, C, M, Y drawing result and K drawing processing unit 13
The binarization process is performed on the drawing result of K in. 2
As the value conversion processing, for example, digital screen processing such as an error diffusion method can be performed. The screen angle for each color is arbitrary, and may be set so as to obtain the best image quality when an image is reproduced based on color output data by an output device such as a printer engine.

The conversion unit 14 converts the C, M, Y, and K planes binarized by the binarization unit 15 based on the drawing result.
Generate CMYK color output data. Since it is a binary value, for example, when a pixel to be drawn is “1” and a pixel not to be drawn is “0”, only when C = M = Y = K = 1, K
While leaving the drawing result '1' on the plane, C,
The rendering result of each of the M and Y planes is set to '0'. In other cases, erase the K plane drawing result (to '0')
Then, the drawing result of each of the C, M, and Y planes is left as it is. In this way, binary CMYK color output data is generated.

FIG. 6 is a flowchart showing an example of the processing of the conversion unit 14 in another embodiment of the color image processing apparatus of the present invention. Here, for example, when the value is “1”, it indicates a pixel to be drawn, and when the value is “0”, it indicates a pixel not to be drawn. In S31, an unprocessed pixel is selected, and values are extracted from the C, M, Y, and K planes for the same pixel. In S32, it is determined whether or not C = M = Y = K = 1. If C = M = Y = K = 1, S3
3, K = 1 is left, and C = M = Y =
Erase as 0. If C = M = Y = K = 1 is not satisfied, in S34, K = 0 and C, M, and Y are left as they are. In S35, it is determined whether or not the processing has been completed for all the pixels. If unprocessed pixels remain, the process returns to S31 to perform the processing on those pixels. When the processing is completed for all the pixels, CMYK binary color output data has been generated.

In this example, based on the drawing result subjected to the binarization processing in the binarization unit 15, the conversion unit 14
Generate MYK color output data. In the digital screen processing in the binarizing unit 15, a black character or a line drawing portion is almost always a pixel of '1' for drawing. Therefore, as described above, the CMYK
Is generated, black characters and line drawing portions remain in the K color output data. If the drawing pixels of the K plane are preserved in the subsequent processing, it is possible to satisfactorily reproduce black characters and thin line portions whose image quality has been deteriorated in the past.

The binary color output data generated in this manner is applied to, for example, the above-mentioned JP-A-11-16.
The black plate generation / undercolor removal processing may be performed using the technology described in Japanese Patent Application Laid-Open No. 4164 or Japanese Patent Application No. 11-150764. If the screen angle and the screen position are constant for each color, the K drawing processing unit 13 also performs the drawing process on the gray part,
In the above, the black plate generation and undercolor removal processing can be performed simultaneously.

In each of the above-described embodiments, C, M, and Y
Although the case of outputting color and color output data of K as a specific color has been described, the present invention is not limited to this. For example, a color system and a color system may be selected according to the characteristics of an output device using color output data. A specific color can be selected.

[0031]

As is apparent from the above description, according to the present invention, the ROP processing performed as a part of the drawing processing can be accurately performed, and the conventional black plate generation and undercolor removal are conventionally performed. Black characters, ruled lines, and the like in a portion having a background color, which has been a problem in the processing, can be correctly reproduced in a single black color. Thereby, for example, there is an effect that the image quality when output by the output device can be dramatically improved.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an example of a process performed by a conversion unit 14 according to the embodiment of the color image processing apparatus of the present invention.

FIG. 3 is an explanatory diagram of an example of an image before and after processing in a conversion unit 14;

FIG. 4 is an explanatory diagram of another example of an image before and after processing in a conversion unit 14;

FIG. 5 is a block diagram showing another embodiment of the color image processing apparatus of the present invention.

FIG. 6 is a flowchart illustrating an example of processing of a conversion unit 14 in another embodiment of the color image processing apparatus of the present invention.

FIG. 7 is a block diagram illustrating an example of a conventional color image processing apparatus.

[Explanation of symbols]

11: PDL analysis unit, 12: CMY drawing processing unit, 13:
K drawing processing unit, 14 conversion unit, 15 binarization unit.

Continued on front page F term (reference) 2C087 AA15 AB05 BA03 BA05 BA07 BD05 BD31 5B057 CE11 CE16 CH18 5C077 LL08 MP06 MP08 NN11 NP10 PP33 PP38 PQ08 RR02 TT03 TT06 5C079 HB03 LA21 LA31 LA34 LB02 LC09 NA03 PA02

Claims (4)

[Claims] 1. A color image processing apparatus which generates four color output data of three colors and a specific color from three color data, wherein the three colors are rendered based on the color data. Drawing processing means, specific color drawing processing means for drawing in the specific color based on the color data, drawing results of three colors by the three color drawing processing means, and drawing of specific colors by the specific color drawing processing means A color image processing apparatus comprising: a conversion unit configured to generate the color output data including the three colors and the specific color from a result. 2. The color image processing apparatus according to claim 1, wherein the specific color rendering processing unit performs rendering only when the three color data indicates a specific color. 3. When the rendering result of the three colors indicates the specific color and the rendering result of the specific color is a value for rendering, the conversion unit sets the rendering result of the specific color as color output data. 3. The color image processing apparatus according to claim 1, wherein the color output data of the three colors is erased. 4. A color image processing apparatus that generates four color output data of three colors and a specific color from three color data, wherein the three colors are rendered based on the color data. Drawing processing means, specific color drawing processing means for drawing in the specific color based on the color data, drawing results of three colors by the three color drawing processing means, and drawing of specific colors by the specific color drawing processing means Result 2
Binarizing means for binarizing, and 3 binarized by the binarizing means
When the three-color rendering result and the specific color rendering result are all data to be rendered based on the color rendering result and the specific color rendering result, the binarized rendering result of the specific color is output as the color of the specific color Data and erase the color output data of the three colors, and otherwise render the rendering result of the specific color as the color output data and output the binary rendering result of the three colors as they are as the color output of the three colors A color image processing apparatus comprising a conversion unit that generates four color output data as data.