JPH10126632A - Image processor, image processing method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speed up image processing by executing a pseudo intermediate processing through the use of a color processing parameter corresponding to the type of an image object to which image data belongs and synthesizing a code showing the change point of the image object. SOLUTION: A luminance density conversion part 202 converts input image data into 24 bit data of CMY. Error data distributed to an original pixel is inputted to an adder 203 from an error memory 204, and it is added to CMY data. Data after addition is inputted to a quantization part 206 and a low-order bit (n<8) is rounded down. Then, 256 combinations which can be expressed by the data length are set to be representative colors and ID information are stored in a representative color table 207 for identifying them. A reproduction table 208 outputs a density value which is actually reproduced in an output pattern for ID information outputted from the representative color table 207. Thus, a color conversion processing, a resolution conversion processing and a binary processing are not required to independently be executed and the high speed processing can be executed.

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 and method for performing N-value processing on input color image data, and a recording medium.

[0002]

2. Description of the Related Art Conventionally, many pseudo halftone processes have been proposed as a method of converting multi-valued input image data into a number of gradations that can be expressed by an output device such as a printer and outputting the same. For example, a dither method or an error diffusion method.

[0003]

However, the conventional output device using pseudo halftone processing has the following problems.

[0004] The resolution of recent output devices has been dramatically improved as compared with the conventional one. Although the image quality of the output image is enhanced by the increase in resolution, the amount of image data to be processed has also been greatly increased. Therefore, the time required for image processing increases,
There is a problem that image output cannot be performed at high speed.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to enable high-speed image processing.

It is another object of the present invention to realize good color reproduction by performing pseudo halftone processing suitable for the characteristics of each image object of an input image.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention is characterized by having the following components.

[0008] The first invention of the present application is an image processing means for processing an image composed of a plurality of image objects,
Storage means for storing a plurality of color processing parameters according to the type of image object, color processing means for performing pseudo halftone processing using color processing parameters according to the type of image object to which the image data belongs, and outputting A synthesizing unit for synthesizing a code indicating a change point of the image object with the image data output from the color processing unit.

A second invention of the present application is an image processing means for processing an image composed of a plurality of image objects,
Storage means for storing color processing parameters corresponding to the type of image object; input means for inputting information on the head position and size of the object; and switching for switching color processing parameters based on the head position and size of the object Generating means for generating a signal, color processing means for performing pseudo halftone processing using a color processing parameter corresponding to the type of the image object to which the image data belongs, and outputting the color processing parameter based on the switching signal Switching means for switching.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing method described in detail below
At the same time as binarizing the input color image data, resolution conversion and color conversion processing are performed.

The principle of the image processing method will be briefly described with reference to FIG. For example, CMY24 as input image data
Bit multivalued data is input. A YMCK output dot pattern (4 ×
Select the combination of 4) and output. Which output pattern is selected for the input image data is determined by selecting the closest distance between the coordinates of the input CMY data and the coordinates of the color data for reproducing the output pattern in the CMY color space as shown in FIG. I do. Further, an error between the reproduction color data (Cr, Mr, Yr) of the pattern and the input data (C, M, Y) is diffused around the target pixel for each CMY color. By this processing, the output is enlarged four times vertically and horizontally with respect to the input as shown in FIG. 4, so that the resolution conversion processing can be performed simultaneously.

Further, by mapping the reproduced color of the output pattern to the input color space and minimizing the error between the input and output spaces, it is equivalent to simultaneously performing the color conversion processing.

FIGS. 1, 2 and 3 are views for briefly explaining the processing flow of this image processing method. FIG. 4 is a diagram showing an entire system using this image processing method, and an image processing unit 4 for processing an input image in a host computer 401.
02, and transfers data to the printer 403. A print control unit 404 in the printer 403 generates print data based on data transferred from the host computer.

FIG. 1 is a block diagram showing a detailed configuration of the image processing unit 402. Input image data is RGB 24bi
If t, the luminance / density conversion unit 202 converts the data into 24-bit CMY data. The adder 203 distributes error data generated in a plurality of pixels that have already been processed to peripheral pixels at a predetermined ratio to the CMY data converted by the luminance density conversion unit 202, and stores the error data in an error memory 204. The error data distributed to the current pixel is stored in the error memory 20.
4 and are added for each color. The data after this addition is input to the quantization unit 206 and the lower n bits (n <
8) Truncate. This performs quantization for reducing the capacity of the next representative color table 207. From the representative color table 207, the print control unit 404 of the printer 403
The side outputs ID information for identifying the output dot pattern. Here, the dot pattern is 4 × 4 as shown in FIG.
In the case of a pixel, if all the bitmap information is included, the data is 16 bits for each of YMCK, that is, a total of 64 bits. However, sending data of 64 bits length per one input pixel is not a very realistic method since the memory capacity provided in the print control unit on the printer side increases. Furthermore, if the output printer has a sufficient resolution, the bitmap information in 4 × 4 is not always necessary. From the above, the data length is reduced from 64 bits to, for example, about 8 bits, and 256 combinations that can be represented by this data length are set as representative colors.
The ID information for identifying this is stored in the representative color table 2.
07 is stored in the table corresponding to the input address. The reproduction color table 208 is a density value (Cr, Mr, Y) for the ID information output from the representative color table 207 that is actually reproduced for the output pattern indicated by the ID information.
r) Output table. This density value is obtained, for example, by converting data obtained by measuring the output pattern of the actually output representative color into a density value. The subtraction unit 205 extracts the density value C output from the reproduction color table 107 from the CMY data output from the addition unit 203.
r, Mr, and Yr are subtracted, and the result is output. This is an error between the input density value and the reproduced color of the output representative color. This error is weighted by a weighting coefficient as shown in FIG. 6 and diffused to surrounding pixels as an error component and stored in the error memory 204.

FIG. 2 is a block diagram for explaining the processing contents of the print control unit 404 in the printer shown in FIG. The memory controller 301 stores the ID information sent from the host computer in the line memory 302, and reads out the data in accordance with the timing of the printer engine. The pattern table 303 converts the input ID information into a dot pattern to be output. That is, for 8 bits of ID information to be input, Y
The ON / OFF of the 16 dots of each color of MCK is output in order of 1 bit for each color in a dot pattern, that is, 4 bits in total.

According to this image processing method, color conversion processing,
The resolution conversion process and the binarization process do not need to be performed independently, and can be performed at high speed, and the memory capacity of the printer main body can be reduced.

(Embodiment 1) With the processing configuration of the image processing method shown in FIG. 1, it is not possible to perform processing according to the characteristics of an input image. For example, the optimum processing parameters are different between a case where the input image is a natural image and a case where the input image is an image such as a character or a graphic. The processing may be performed with parameters optimal for the characteristics of each image data by providing respective modes. However, when objects having different characteristics exist in one page, processing parameters suitable for each object are used. There is room for improvement that processing cannot be performed.

FIG. 1 is a diagram showing the overall configuration of an image output system according to the present embodiment. Host computer 10
An application 102 exists on the server 1 and creates image data such as text, graphics, and natural images, and transfers the image data to a printer driver in the OS. At this time, as the data 103 sent from the application 102, in addition to the above-described image data, identification information for each of a plurality of image objects forming one page of image data is sent. The image processing unit 106 in the printer driver 105 generates data to be transferred to the printer based on the image data and the object identification information, and outputs the data to the printer 108 via the data output unit 107.

In the image processing unit 106, the printer driver 105 is controlled by the CPU of the host computer 101.
FIG. 8 shows a flow of processing executed based on the above program. In the following, those having the same processing contents as those in FIG.

The object identification information sent from the application 102 is input from the signal line 806 in FIG. 8, and is input to each of the switches 807, 808, 813, and 814. The object identification information is input as, for example, 1-bit data for each pixel. When "0" indicates an image object of a natural image, and when "1", a graphic or text image object is input as input image data. Shall be. Each switch is switched according to this value to select the representative color table 1 and the representative color table 2, and the reproduction color table 1 and the reproduction color table 2. The representative color table 1 and the reproduction color table 1 are selected when the object identification information is “0”, that is, when the object is a natural image object. The representative color table 2 and the reproduction color table 2 have the object identification information “1”. Is selected, that is, when the object is a graphic object. These tables select the optimal dot pattern for each object, and have the reproduced color values of the dot pattern as tables.

Here, when different ID information is assigned to each of the two types of representative color tables, when the same bit number of 8 bits as in the conventional example is to be used, the elements of each table are reduced. Is not reduced, the number of bits of the ID information increases, the transfer load increases, and the memory capacity of the printer also increases. Accordingly, in the present invention, 256 bits that can be represented by 8 bits of ID information
One identification code indicating that the table has been switched is provided from among the codes, and the printer selects an output pattern based on the code. For example, among the 8-bit codes 0x00 to 0xFF, 0x00 to 0xFE are index information for selecting an output dot pattern;
xFF is assigned to an identification code indicating that the representative color table and the reproduction color table have been switched according to the object identification information. By doing so, the same code can be assigned to the ID information indicating different dot patterns in the representative color table 1 and the representative color table 2, so that the code use efficiency is improved. Identification code adding unit 8
Reference numeral 15 denotes an identification code 0xFF at the timing when the object identification information transmitted from the application side changes.
Is output, the ID information code other than the identification code is sent to the printer, otherwise, the identification code is not sent and only the ID information code is output.

Next, FIG. 9 is a diagram for explaining the processing contents of the print control unit 109 in the printer. The 8-bit data of the ID information sent from the host computer is temporarily stored in the line memory 902, read out and output by the memory controller 901. The identification code determination unit 903 identifies the identification code 0xFF in the ID information.
Is detected, a control signal for switching the switches 904 and 907 is output. When the identification code determination unit 903 detects the identification code 0xFF, the timing control unit 908
Outputs a timing control signal to the
Synchronize the information with the printer engine. When the timing control signal is input, the timing control unit 908 does not send the identification code to the switch 904, but sends the next ID information to the switch 904.

Since the host computer has switched between the representative color table and the reproduction color table according to the object identification information, the pattern table 1 and the pattern table 2 containing dot pattern information corresponding to the table are respectively switched. In this way, when the host computer uses the natural image object table, the printer also uses the natural image pattern table, and when the graphic object table is used, the printer also uses the graphic pattern table. It can be used.

Here, for the sake of simplicity, only two representative color tables, reproduced color tables, and pattern tables are prepared. Of course, more tables may be provided and these tables may be provided according to the characteristics of the object. You may switch.

In the internal configuration of the host computer described with reference to FIG. 8, it is the application that generates the image object identification information. However, other information such as a system function called inside the OS is used to generate the image object identification information. A configuration in which characteristics are automatically determined and object identification information is generated may be used.

In this embodiment, two types of objects are distinguished by one identification code. However, for example, for three or more types of image objects, the number of identification codes to be allocated is increased to identify the objects. It is also possible.

With the above configuration, it is possible to perform processing using the optimum processing parameters for each image object, and it is possible to obtain optimum image quality no matter what image is input.

Further, since the necessary information transfer is minimized, the processing can be realized without lowering the data transfer efficiency. Further, by switching the table for each image object, it is possible to assign a different dot pattern to the same code, so that the encoding efficiency is high.

(Embodiment 2) Embodiment 2 is characterized in that when an image object is a rectangular object, an identification code and a parameter indicating the size of the object are sent at the beginning of the object.

The configuration of the image output system according to the second embodiment is the same as that of FIG. A feature of the present embodiment is that the information received by the image processing unit 106 in the printer driver 105 from the application 102 simultaneously sends the object size information in addition to the object identification information. Also, the object identification information is not sent at all the boundaries between different objects on the image, but when there is a rectangular object such as a hatched portion in FIG.
Only at the head pixel position, object identification information, and Width and Height indicating the size of the object
Is sent.

FIG. 10 is a diagram for explaining the image processing unit according to the present embodiment. Components having the same functions as those in FIG. 8 are denoted by the same reference numerals, and description thereof is omitted. The object identification information and the object size information sent from the application are input to the table switching signal generation unit 1005. Here, a table switching signal for switching between the representative color table and the reproduction color table is generated based on the input object information, and output to the signal line 806. This table switching signal is generated at the pixel position of the boundary between the objects as shown by the black circle in FIG. By this table switching signal, the switch 80
7, 808, 813, and 814 are switched to use the representative color table and the reproduction color table for each object.

The object information adding unit 1017 adds the object information to the ID information based on the object identification information and the object size information input from the application, and transfers the ID information to the printer. FIG.
Shows the relationship between the object information added by the object information adding unit 1017 and the ID information. ID information of each pixel 8
The object information adding unit 1 is transmitted in units of bits, and at the timing of the object information generation point shown in FIG.
The identification code 0xFF is output by inputting the object identification information input to 017. After that, the input object size information is
h16 bits and Height 16 bits are sent. Thereafter, only the ID information is sent. Of course, the data length of Width and Height may be changed according to the size of the object handled by the system.

FIG. 14 is a diagram for explaining the processing contents of the print control unit of the printer according to the present embodiment. FIG. 14 has the same configuration as that of FIG. 9 illustrating the print control unit of the first embodiment, but includes an object information determination unit 1403 instead of the identification code determination unit. When the object information determination unit detects the identification code 0xFF when the data as shown in FIG. 13 is sent from the host computer, the size information Width and He of the subsequent object are detected.
and receives a signal for switching the pattern table at the boundary of the rectangular object represented by a black circle in FIG.
7 is output. When the identification code is input to the object information determination unit 1403, the timing control unit 1408
To the switch 1404 without outputting a code to the switch 1404 until the ID information following the object information is input as in the first embodiment.
Adjust the timing of D information.

With the above configuration, the amount of information to be transmitted for optimizing the processing for each image object can be minimized, the amount of information to be transmitted from the host computer to the printer can be reduced, and the speed can be increased.

For a rectangular object, the information indicating the head position of the object and the information on the object size are sent at the head position, thereby reducing the amount of data transfer required to change the processing parameters for each object. can do.

(Other Embodiments) The functions of the above-described embodiments are implemented in an apparatus or a computer in a system connected to the various devices so as to operate various devices so as to realize the functions of the above-described embodiments. The present invention also includes a computer program (CPU or MPU) of the system or apparatus that supplies the program code of software for operating the various devices according to the stored program.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, for example, the program code The storage medium storing the information constitutes the present invention.

As a storage medium for storing the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, DC-ROM, magnetic tape,
A nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer, or another program. Needless to say, even when the functions of the above-described embodiments are realized in cooperation with application software and the like, such program codes are included in the embodiments of the present invention.

Further, the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, and then stored in the function expansion board or the function storage unit based on the instruction of the program code. It is needless to say that the present invention also includes a case where a provided CPU or the like performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0041]

According to the present invention, image processing can be performed at high speed.

Further, by performing pseudo halftone processing suitable for the characteristics of the input image object, good color reproduction can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a pseudo intermediate process performed by a host computer.

FIG. 2 is a diagram illustrating a print control process performed by a printer.

FIG. 3 is a diagram illustrating the configuration of the entire system.

FIG. 4 is a diagram illustrating a relationship between input data and an output dot pattern.

FIG. 5 is a diagram illustrating a relationship between input data and reproduced color data of an output pattern to be selected in a CMY color space.

FIG. 6 is a diagram showing a diffusion matrix for diffusing an error generated in pseudo halftone processing.

FIG. 7 is a diagram illustrating an overall configuration of a system according to the first embodiment.

FIG. 8 is a diagram illustrating an image processing unit according to the first embodiment.

FIG. 9 is a diagram illustrating a print control unit according to the first embodiment.

FIG. 10 is a diagram illustrating an image processing unit according to a second embodiment.

FIG. 11 is a diagram illustrating a relationship between an image object and information of the object according to the second embodiment.

FIG. 12 is a diagram illustrating a position where a table switching signal is output in the second embodiment.

FIG. 13 shows object information and an ID according to the second embodiment.
It is a figure showing the relation of information.

FIG. 14 is a diagram illustrating a print control unit according to the second embodiment.

Claims (14)

[Claims] 1. An image processing means for processing an image constituted by a plurality of image objects, comprising: storage means for storing a plurality of color processing parameters corresponding to a type of the image object; Pseudo halftone processing using color processing parameters corresponding to the type, color processing means for outputting and outputting, and a code indicating a change point of the image object is synthesized with the image data output from the color processing means. An image processing apparatus comprising: a synthesizing unit. 2. The image processing apparatus according to claim 1, wherein the color processing parameter is a table. 3. An image processing apparatus according to claim 1, wherein said storage means stores image color processing parameters and graphics color processing parameters. 4. The code according to claim 1, wherein the code indicating the change point of the image object is one of codes that can be represented by a data amount of the image data output from the color processing unit. Image processing device. 5. The image processing apparatus according to claim 1, wherein the image data output from the color processing means is a code indicating a dot pattern composed of predetermined pixels. 6. The image forming unit further includes an output unit that outputs, to the image forming unit, image data output from the color processing unit and a code indicating a change point of the image object. Storage means for storing a plurality of development tables corresponding to each of the plurality of processing parameters; development means for developing image data output from the color processing means into a dot pattern using the development table; 2. The image processing apparatus according to claim 1, wherein the table is switched based on a code indicating a changing point of the table. 7. The image processing apparatus according to claim 1, wherein said color processing means diffuses an error generated by the pseudo halftone processing to peripheral pixels. 8. An image processing means for processing an image composed of a plurality of image objects, a storage means for storing a color processing parameter corresponding to a type of the image object, and information relating to a head position and a size of the object. Input means for inputting the image data, generating means for generating a switching signal indicating switching of color processing parameters based on the head position and size of the object, and color processing parameters according to the type of image object to which the image data belongs. An image processing apparatus comprising: a color processing unit that performs pseudo halftone processing and outputs the color processing parameter; and a switching unit that switches the color processing parameter based on the switching signal. 9. The image processing apparatus according to claim 8, wherein the image object is a rectangular object. 10. The image processing apparatus according to claim 8, wherein the generation unit generates the switching signal at a boundary of the image object based on a head position and a size of the image object. 11. An image processing method for processing an image composed of a plurality of image objects, comprising: an image to which image data belongs from among a plurality of color processing parameters corresponding to types of image objects stored in advance. A color processing step of selecting a color processing parameter according to the type of the object and performing a pseudo halftone process; and synthesizing a code indicating a change point of the image object with the image data subjected to the pseudo halftone process. An image processing method comprising: 12. A recording medium for storing a program for realizing the image processing method according to claim 11. 13. An image processing method for processing an image composed of a plurality of image objects, comprising: inputting information relating to a head position and a size of an image object; Generating a switching signal indicating switching, performing pseudo halftone processing using a color processing parameter corresponding to a type of an image object to which the image data belongs, and switching the color processing parameter based on the switching signal. Image processing method. 14. A recording medium for storing a program for realizing the image processing method according to claim 13.