JPH10114110A - Image processing method, image processing system, image processing device, and image output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device wherein the number of bits assigned to ID information can be changed, the number of representative colors can be increased and an inputted full color image is converted to a binary value image or a multiple value image having limited number of gradations. SOLUTION: In a memory controller 801 of a printer, transmitted ID information is stored in an input buffer 802 and data is read in response to a timing of a printer engine. A CMYK(cyan, magenta, yellow, black) information converting section 803 converts inputted ID information having (m) bits to a dot pattern to be outputted by using pattern tables 804-806. The number of bits of the ID information are varied corresponding to printing modes. The output from the CMYK information converting section 803 executing the information conversion corresponding to the number of bits inputted thereto is stored in an output buffer 808. It is read from the output buffer 808 and is printed by the printer engine.

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 for converting a full-color input image into a binary image or a multivalued image having a limited number of gradations.

[0002]

2. Description of the Related Art Conventionally, a number of pseudo halftone processes have been proposed as a method of converting multi-value image data from a host computer into a number of tones that can be expressed by an output device such as a printer and outputting the same. ing. For example, a dither method or an error diffusion method. In addition, the present applicant also filed Japanese Patent Application No. 7-10733.
No. 0 proposes an image processing method.

As the pseudo halftone processing, multi-valued image data from a host computer is converted into, for example, a YMCK 4 × 4 dot pattern that can be output by a printer. Here, when the dot pattern to be printed uses all 4 × 4 dot patterns,
YMCK 16 bits each, a total of 64 bits of data is required. However, sending data having a length of 64 bits per input pixel is not a very realistic method because the memory capacity provided in the print control unit on the printer side increases. Furthermore, if the output printer has a sufficient resolution, the 4 × 4 all-bit pattern 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.
Information for identifying this is sent to the printer as ID information.

This image processing method not only binarizes input full-color image data but also performs resolution conversion and color conversion simultaneously.

As described above, according to this image processing method, the color conversion processing, the resolution conversion processing, and the binarization processing do not need to be performed independently, and can be performed at high speed. Furthermore, the memory capacity of the printer body is reduced.

[0006]

However, in the processing configuration of the image processing method described in the prior art, the dot pattern is compressed from 64 bits to n bits (about 8 bits) due to the limitation of the memory capacity of the printer. Then, 2 n combinations are fixed as the representative colors. Since the compression ratio is constant by this compression processing, satisfactory gradation and color reproduction may not be performed depending on the image in some cases.

Further, if the representative color table is provided with n bits or more in order to solve the above problem, the memory capacity of the printer is increased, which leads to an increase in cost.

[0008]

According to a first aspect of the present invention, an input color multi-valued image is converted into a number of tones that can be output by an image output device, and image output is performed. In the image processing method to be performed, the pixels of the input color multi-valued image are converted into dot pattern pixels having the number of gradations that can be output by the image output device, and the dot pattern pixels are converted into ID information representing a representative color having a small number of bits. Then, the number of bits of the ID information is changed according to the output mode, the ID information is transmitted to the image output device, and the ID information is converted into a dot pattern and output.

According to a second aspect of the present invention, in the image processing method of the first aspect, when the pixels of the input color multi-valued image are converted into dot pattern pixels having the number of gradations that can be output by the image output device, An error between the reproduced color data when the representative color of the dot pattern is output and the pixel data of the input color multivalued image is obtained, and the obtained error is distributed to peripheral pixels at a predetermined ratio.

According to a third aspect of the present invention, there is provided an image processing apparatus and an image output apparatus for converting an input color multivalued image into a number of gradations that can be output by an image output apparatus and outputting the image. In the image processing system, the image processing device converts the pixels of the input color multi-valued image into dot pattern pixels having the number of tones that can be output by the image output device, and converts the dot pattern pixels into IDs representing representative colors having a small number of bits. Information, and the number of bits of the ID information is changed according to the output mode.
The D information is transmitted to the image output device, and the image output device converts the ID information into a dot pattern according to an output mode and outputs the dot pattern.

According to a fourth aspect of the present invention, there is provided an image processing apparatus for converting an input color multivalued image into a number of gradations that can be output by an image output device and outputting the image. Is converted into dot pattern pixels having the number of gradations that can be output by the image output device, and the dot pattern pixels are converted into ID information representing a representative color having a small number of bits.
The number of information bits is changed according to the output mode, and the ID information is transmitted to the image output device.

According to a fifth aspect of the present invention, there is provided an image processing apparatus comprising:
When converting to a pattern pixel, an error between reproduced color data when the representative color of the dot pattern is output and the pixel data of the input color multi-valued image is obtained, and the obtained error is determined by a predetermined ratio to peripheral pixels. Can also be allocated.

According to a sixth aspect of the present invention, there is provided an image output apparatus for receiving and outputting ID information representing a representative color having a different number of bits for each output mode, wherein: an input buffer for storing the received ID information; I read from
A conversion unit for converting the D information into a dot pattern in accordance with an output mode, and an output buffer for storing the dot pattern.

The invention according to claim 7 is the image output apparatus according to claim 6, wherein said conversion means has a table storing said dot pattern corresponding to said ID information.

In the image output apparatus according to the present invention, the table is provided for each output mode, and the table is selected according to the output mode.

According to a ninth aspect of the present invention, in the image output device according to the seventh aspect, the table is provided with one table corresponding to a maximum bit of the ID information, and a dot pattern for the ID information of a small number of bits is shared. is there.

According to the tenth aspect of the present invention, the image output device is a printing device.

In the eleventh aspect, the output mode corresponds to the number of passes to be printed.

In the twelfth aspect of the present invention, the capacity of the output buffer changes according to the printing pass, and the table is provided according to the change in the capacity.

According to a thirteenth aspect of the present invention, there is provided a recording medium storing a program for performing a process of converting an input color multivalued image into a number of gradations that can be output by an image output device, wherein Pixels are converted into dot pattern pixels with the number of gradations that can be output by the image output device,
This is a recording medium that stores a program for converting a pattern pixel into ID information representing a representative color having a small number of bits, changing the number of bits of the ID information in an output mode, and transmitting the ID information to an image output device.

According to a fourteenth aspect of the present invention, there is provided a recording medium storing a program for performing processing of receiving and outputting ID information representing a representative color having a different number of bits for each output mode. A computer system comprises a buffer, a conversion means for converting the ID information read from the input buffer into a dot pattern in an output mode, and an output buffer for storing the dot pattern. Is a recording medium storing a program to be executed.

With the above configuration, it is possible to lower the compression ratio of image data, and to achieve better gradation.
Images with good color reproducibility can be printed.

Further, since a plurality of tables are provided, by assigning various dot generation patterns to the tables, it is possible to perform printing giving a different impression.

[0024]

Embodiments of the present invention will be described with reference to the drawings.

First, the entire flow of the image processing of the present invention will be described.
This will be described with reference to FIG.

FIG. 1 is a diagram showing an entire system using this image processing method.

In FIG. 1, a host computer 10
1 and the printer 103 are connected. The processing on the host computer side is represented by an image processing unit 102 in the host computer, and the processing unit performing processing in the printer 103 is represented by a print control unit 104 in the printer 103. These processes are performed by respective computers. The host-side image processing unit 102 is often implemented as a printer driver.

The data to be printed is processed by the image processing section from the host computer 101 side, and is transferred to the printer 103 as print data. Printer 10
3, the host computer 10
Data to be actually printed is generated based on the data transferred from the first side.

FIGS. 2 and 3 show a specific example of a system configuration in which the present invention is implemented.

FIG. 2 is a block diagram showing an example of the configuration of the host computer 1 on which the processing of the present invention is performed. In FIG. 2, reference numeral 210 denotes a CPU, which executes processing in a host computer. 212 is ROM
In this case, a program such as a BIOS is stored in advance. A main memory 214 stores programs and data and is used by the CPU 210. A display controller 216 interfaces with the display 218 and performs display on the display 218. Reference numeral 220 denotes a disk controller such as SCSI, which interfaces with the hard disk 222 and the like. The hard disk 222 stores programs, data, and the like, and is called by the main storage as needed and used by the CPU. A floppy disk controller 224 interfaces with the floppy disk 226. A printer controller 228 interfaces with the printer 230. A keyboard controller 232 interfaces with the keyboard 234. A mouse controller 236 interfaces with the mouse 238. Display 21
8. User keyboard and mouse 238
Configure the interface.

FIG. 3 shows an example of the configuration of the printer of the present invention. In FIG. 3, a control unit 320 includes a CPU 301 such as a microprocessor, a ROM 302 storing a control program of the CPU 301 and various data,
Input buffer 304 and output buffer 305 of PU 301
A RAM 302 and the like used as a work area are provided. Reference numeral 321 denotes a head driver.
Input print data, and according to the print data,
The recording heads 330 to 333 corresponding to the respective colors are driven. Reference numeral 324 denotes a carriage motor for driving the carriage 1. A paper feed motor 325 rotates a paper feed roller, a paper feed roller, and the like to convey the recording paper. Reference numerals 322 and 323 denote motor drivers that drive the corresponding motors in accordance with instructions from the control unit 320, respectively. 326 is a recording paper sensor for detecting the presence or absence of a recording paper, and 327 is a sensor for detecting whether or not a cartridge is mounted. 328 is the host
Print data input from an external device such as a computer is received, and the print data is transmitted to the control unit 320.

The mechanism of the printer other than the print controller 320 may be referred to as a printer engine 340.

The data sent from the host computer 101 to the printer 103 will now be described with reference to FIGS.
This will be described with reference to FIG.

As image data to be printed, for example, data of one pixel is CMY (cyan, magenta,
A description will be given of a case in which each color (blue-green, magenta, yellow) is composed of 8-bit multi-value data of 8 bits in total. Binary YMCK (yellow, magenta, cy) that reproduces the color closest to this input value
an, black: select a combination of output dot patterns (4 × 4) of yellow, magenta, blue-green, black)
Perform output. FIG. 4 shows this state. In this figure, one 24-bit pixel data is composed of 4 × 4 16 pixels.
4 bits of 1 bit for each of YMCK, that is, 4 × 4
It has been converted to x4 64-bit data.

The output pattern to be selected for the image data is determined by determining the distance between the coordinates of the input CMY data and the coordinates of the color data for reproducing the output pattern in the CMY space as shown in FIG. Choose one. 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.

The processing of this error will be described with reference to FIG. In FIG. 6, * indicates a target pixel, and an error for this pixel, that is, a difference between the input data and the reproduced color data based on the output pattern in FIG. The error with respect to the pixel of interest is distributed in a predetermined proportion from the pixel on the right of the pixel of interest to pixels around the pixel in order. FIG.
Are the numbers of the proportional distribution of the error with respect to the target pixel * and the pixel at that position. For example, an error is distributed in proportion to 7 immediately below the pixel of interest, and in a proportion of 5 to the lower right and lower left. The distribution of the error is distributed to pixels output after the target pixel. In the example shown in FIG. 6, errors are proportionally distributed for 12 pixels around the pixel of interest.

By the above-described processing, as shown in FIG. 4, the output is enlarged to 16 pixels that are four times longer and wider for one input pixel, so that the resolution conversion processing is performed simultaneously. Also, as shown in FIGS. 5 and 6, the reproduction color of the output pattern is mapped to the input color space and the error between the input and output spaces is minimized, so that the color conversion process is also performed at the same time. Is equivalent to

When the dot pattern to be printed is 4 × 4 as shown in FIG.
When using × 4 bitmap information, 1 for each of YMCK
6 bits, a total of 64 bits of data are required. However, sending data having a length of 64 bits per input pixel is not a very realistic method because the memory capacity provided in the print control unit on the printer side increases. Furthermore, if the output printer has sufficient resolution,
× 4 All bitmap information is not always necessary. From the above, the data length is 64 bi
For example, 256 bits that can be represented by this data length are set as representative colors, and information for identifying the combinations is sent to the printer as ID information as ID information.

Therefore, in FIG. 1, the print information sent from the host computer 101 to the printer 103 is this ID information.

In the present invention, the number of bits allocated to ID information can be changed, the number of representative colors can be increased, the compression ratio of image data can be reduced, and the gradation And an image with good color reproducibility can be printed.

(First Embodiment) FIGS. 7 and 8 show the structure of the first embodiment of the present invention.

FIG. 7 shows the configuration of the image processing section of FIG. 1 according to the present invention. FIG. 8 shows the configuration of the print control unit of FIG. 6 in the present invention. These are realized by a program executed on the system configuration of FIGS.

In the first embodiment, as shown in FIG. 7, representative color tables 711 to 713 corresponding to a plurality of different bit numbers (64 bits or less) are provided in advance. The number of bits of data (the number of bits of ID information) can be changed. The print mode selection unit 106 selects a table for converting a plurality of representative color tables into a specific number of bits. With such a configuration, optimal printing in the print mode can be realized.

The operation of the image processing section of the host computer having the configuration shown in FIG. 7 will be described.

In FIG. 7, when the input image data is RGB 24-bit data, the luminance / density conversion unit 701 converts the data into 24-bit CMY data. The addition unit 702 adds the error from the error processing unit 703 to the CMY data converted by the brightness / density conversion unit 701. The error processing unit 703 distributes error data generated in a plurality of pixels that have already been processed to peripheral pixels at a predetermined ratio and stores the error data in an error memory 704. The error data corresponding to the current pixel stored in the error memory 704 is read out, input from the error processing unit 703, and added for each color. The data after the addition is input to the quantization unit 705 and the lower n bits are discarded. This is because quantization is performed to reduce the capacity of the next representative color tables 711 to 713. The number n of bits to be discarded is switched according to the print mode input to the print mode selection unit 706 based on information from the print mode selection unit 706.

The data from the quantization unit 705 has an ID
An ID representing an m-bit representative color by the information conversion unit 707
Changed to information. In this case, the print mode selection unit 706
, The ID information conversion unit 706 changes the representative color tables 711 to 713 used for conversion, and changes the number m of output bits according to the print mode.

The CMY information conversion unit 708 uses the reproduced color tables 715 to 717 to output the actually reproduced density values (Cr, Mr, Yr) of the output pattern indicated by the ID information for the output ID information. Is output. This density value is obtained, for example, by converting data obtained by measuring the actually output representative color into a density value. A print mode selection unit 706 selects and uses a reproduction color table having the same bit number as the representative color table.
In the subtraction unit 709, the CM output from the addition unit 702
The density values Cr, Mr, and Yr output from the CMY information conversion unit 708 are subtracted from the Y data, and the result is output. This is an error between the input density value and the reproduced color of the output representative color. The error is weighted as shown in FIG. 6 by the error processing unit 703, diffused as an error component for surrounding pixels, and stored in the error memory 704.

On the other hand, the processing of the present invention in the print control unit 104 in the printer shown in FIG. 1 will be described with reference to FIG.

In FIG. 8, the memory controller 80
In I, I sent from the host computer side
The D information is stored in the input buffer 802, and the data is read according to the timing of the printer engine. Next, using the pattern tables 804 to 806 by the CMYK information conversion unit 803, the input m-bit ID
Converts information to a dot pattern to be output. ID
Since the number of bits of information differs depending on the print mode, the CMYK information conversion unit 803 performs information conversion according to the number of bits of input information by the output of the mode selection unit 809. Specifically, the pattern table 80
A table corresponding to the number of bits of the ID information is selected from 4 to 806, and converted into a dot pattern to be output corresponding to the input ID information. This means that, for the input ID information mbit, ON / OFF of the 16 dots of each YMCK color is output in order within the dot pattern, one bit for each color, that is, a total of 4 bits.
The output from the CMYK conversion unit is output buffer control unit 80
7 and stored in the output buffer 808. The data is read from the output buffer 808 by the output buffer control unit 807 in synchronization with the operation of the printer, and is printed by the print engine.

Here, the mode information to the mode selection unit 809 may be transmitted in the form of a header attached to the image signal from the host computer, or may be transmitted as a signal different from the image signal. You may come.

As described above, when a plurality of pattern tables are prepared, the amount of tables to be held increases. But,
For example, the dot generation pattern can be changed for each table such as a dot concentration type for Table 1, a dispersed type for Table 2, a halftone type for Table 3, and the like, and images with various impressions can be printed. For example, when the compression ratio is high, the gradation property is largely lost, so that it is generally possible to use a dot concentration type having good gradation expression.

(Second Embodiment) The capacity of a memory (RAM) required for image processing on the printer side is 1 li in the main scanning direction.
The capacity of an output buffer for storing data required for printing differs depending on how many scans are required until all of the ne are printed (this is called the number of passes). Therefore, the number of bits (the number of bits of ID information) assigned to one pixel which can be input from the host side is changed according to the number of printing passes of the printer.
It is possible to print a high-quality image by effectively using the memory and reducing the data compression rate as much as possible.

Here, the number of printing passes will be described with reference to FIGS.

FIG. 9 illustrates the case of printing in one pass. FIG. 9A shows a header, and there are 128 nozzles for each color of CMYK. FIGS. 9B and 9C show printing using all the nozzles of each color. In this case, since all colors are printed each time the head scans a print area for 128 nozzles, the head moves to the next print area by one scan.

FIG. 10 shows how printing is performed in two passes. The very first scan is shown in FIG. In this drawing, the lower half of the head is used to mask the nozzles in the lower half area, and printing is performed without using the whole. Next, the recording paper is fed by a length corresponding to half of the head, and in FIG. 10B, a mask is applied to the nozzles in the upper half of the head, and printing is performed using the nozzles not printed in the previous scan. Then, printing of a half-length portion of the head is completed. The nozzles in the lower half of the head are also masked and printed on new parts at the same time.

FIG. 10C shows the third scan, which indicates that printing for the length of the head has been completed and half of the next head has begun printing.

As described above, by performing printing in two passes with a mask, for example, adjacent nozzles are driven only during separate scanning, and a more precise printing effect can be obtained.

As an example of the above mask, a case of a staggered mask will be described with reference to FIG.

FIG. 11 shows an example using a staggered mask. As shown in FIG. 11, when a staggered mask is used, a mask is applied by designating nozzles to be alternately shot by adjacent nozzles and nozzles not to be shot. Therefore, half of the image data actually sent to the head is masked and is unnecessary. It suffices if there is image data of the portion indicated by the circle in FIG. That is, FIG.
In the case of 1, the image data newly required is not limited to 128 nozzles, but may be half the data of 64 nozzles.

FIG. 12 shows how printing is performed in four passes. As can be seen from FIGS. 12 (a) to 12 (d), four scans are carried out by using nozzles each having a length of 1/4 of the length of the head and without the mask, thereby performing one scan of the head.
The printing for the length of / 4 has been completed.

Now, how the required memory capacity of the output buffer changes depending on the number of print passes will be described. The capacity of the output buffer is as follows: capacity of output buffer = read portion + write portion = (number of development bits corresponding to path) * (CMYK) * (number of pixels in main scanning direction) + (number of nozzles) * (CMYK) * (main scanning (The number of pixels in the direction). In this case, after being developed into an output pattern corresponding to the main scanning direction, masking is performed to make the number of bits corresponding to the path, and the bit number is stored in the read section of the output buffer. When transferred to the print engine, the data is expanded by the mask information to make the number of bits corresponding to the nozzle, and this is written
The print engine head is driven by the output of the write unit. This will be described in detail in each pass.

As an example, an input is set to 300 dpi, and an output is set to 1200 dpi using a 4 × 4 output pattern.
Description will be made in the case of expanding to i.

FIG. 13A shows the configuration of an output buffer in the case of one-pass printing.

In the case of one pass, since no mask is applied,
The read section requires the same capacity as the write section. Therefore, the memory required for one-pass printing on A4 paper is Approximately 1.3 megabytes.

FIG. 13B shows a case of two-pass printing. In the case of two-pass printing, as described above, the amount of newly required image data may be half the data amount, and therefore, the read portion of the output buffer may be half the number of bits corresponding to the nozzles.

Therefore, the output buffer required for A4 paper is 64 * 4 (8.5 * 1200) + 128 * 4 * (8.5)
* 1200) = 7833600 bits, which is about 1 megabyte.

Here, when compared with the capacity of the output buffer for one-pass printing, it is about 300 kilobytes less.
Therefore, this space can be used to increase the number of bits in the representative color table.

In this case, for example, the ID information is 8 bits,
An example will be described in which four representative color tables of 10 bits, 12 bits, and 14 bits are provided.

A representative color table having 8 bits of ID information requires 256 * (4 * 4 * 4) = 16,384 bits, that is, about 2 kilobytes. In addition, a representative color table of 10 bits of ID information requires 1024 * (4 * 4 * 4) = 65,536 bits, that is, about 8 kilobytes. ID information is 1
The 2-bit representative color table requires 4094 * (4 * 4 * 4) = 262,144 bits, that is, about 33 kilobytes is required. A representative color table having 14 bits of ID information requires 16376 * (4 * 4 * 4) = 1,048,064, that is, 131 kilobytes is required. When all of these are added, 2 + 8 + 33 + 131 = 174, which is approximately 174 kilobytes, and the empty portion of the output buffer described above was 300 kilobytes. Therefore, such a representative color table for the four pieces of ID information is also sufficiently stored. can do. These representative color tables can be created, for example, from a ROM to an empty RAM area at the time of initialization.

Similarly, in the four-pass printing shown in FIG. 13C, the capacity required for the output buffer can be calculated in the same manner as 128 * 4 * (8.5 * 1200) + 32 * 4 (8 .5
* 1200) = 652800 bits, which is about 0.8 megabytes. Therefore, compared to the case of one pass, there is a margin of about 500 kilobytes.
This can be used for the representative color table.

In order to increase the number of passes, it is necessary to take into account the amount of memory required for control and the like in the calculation. Obviously, the capacity can be increased.

Further, since one-pass printing is not practical in practice, considering two-pass printing as a reference,
By utilizing the fact that the number of memories required for output is reduced by increasing the number of printing passes, and assigning it to the number of bits in the representative color table, it is possible to obtain images with higher gradation and color reproducibility. Becomes

(Third Embodiment) In the first and second embodiments, as shown in FIG. 7, the pattern table has the same number of I bits having different bit numbers as the representative color table and the reproduction color table.
The table has a number of tables corresponding to the D information.
In this configuration, the capacity of the table increases.

For this reason, the configuration of the print controller for reducing the capacity of the table by devising the configuration of the pattern table is the third embodiment described with reference to FIGS.

In FIG. 14, components having the same functions as those in FIG. 8 are denoted by the same reference numerals. What is greatly different in FIG. 13 is the pattern table 1304.
The structure of the pattern table 1304 is shown in FIG.
5 will be described.

In FIG. 15, the pattern table 13
04 stores a dot pattern of the ID information at an address corresponding to the ID information. This ID information
Since the number of bits changes, holding a plurality of bits separately for each bit leads to an increase in the memory used. Therefore, the pattern table has a structure as shown in FIG. That is,
As shown in FIG. 14, an n-bit table, which is the maximum number of bits of the ID information, is created in advance. And
Each bit pattern is stored so that ID information of a smaller number of bits and a dot pattern for an address corresponding to the lower bit are shared.

As described above, by sharing the pattern table with the ID information having different numbers of bits, the capacity of the memory to be used can be reduced as compared with the case where the pattern table is created for each ID information of each bit number.

In FIG. 14, the CMYK information conversion unit 8
Numeral 03 reads the address of the corresponding number of bits specified by the mode selection unit 809 from the common pattern table 1304 having a capacity of n bits. Other operations are the same as the operations of the print control unit shown in FIG.

In the above embodiment, the printer has been described by taking an ink jet printer as an example, but it goes without saying that the present invention can be applied to other printers.

The above embodiment has been described in connection with the case where the program is executed. Therefore, the present invention is also applied to a case where the above is achieved by supplying a program to a system or an apparatus. The functions of the present invention described above can be realized and the effects of the present invention can be enjoyed by reading the storage medium storing the program for achieving the present invention by a system or an apparatus. This recording medium includes, for example, a floppy disk, a hard disk, and a CD.
-ROMs, magnetic tapes, magneto-optical disks, memory cards, ROM cassettes, etc. are also included.

Further, it goes without saying that the present invention can be implemented on a plurality of systems.

Further, in the present invention, a part or all of the above configuration can be configured by hardware.

[0083]

As described above, the information to be sent to the printer can be selected by the print mode without fixing the number of bits of the image information encoded by the ID information by the representative color. With such a configuration, the compression ratio of image data can be reduced, and an image with better gradation and color reproducibility can be printed.

On the printer side, a plurality of pattern table groups having different bit widths are prepared, and the table having the best memory use efficiency is selected and used.

As a result, optimum printing can be performed regardless of the compression ratio. Also, since there are a plurality of tables, it is possible to perform printing giving a different impression by assigning an appropriate dot generation pattern to each table.

On the printer side, depending on the printing path,
The amount of memory used in the output buffer in the printer required for printing changes. By utilizing this, when the number of passes increases and the amount of output buffer used decreases, that portion is used as a conversion table for converting ID information into a dot pattern, and a table with a larger number of bits is used. Can be prepared.

A pattern table for converting ID information corresponding to the maximum number of bits into a dot pattern is prepared on the printer side, and the table is shared for ID information having a smaller number of bits. By configuring the conversion table in this way, the capacity of the memory can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the entire flow of image processing according to the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a host computer of the present invention.

FIG. 3 is a block diagram illustrating a configuration example of a printer according to the invention.

FIG. 4 is a diagram illustrating a relationship between input image data and an output dot pattern in the image processing of the present invention.

FIG. 5 is a diagram showing a relationship in CMY space between input data and reproduced color data of an output pattern to be selected in the image processing of the present invention.

FIG. 6 is a diagram illustrating a diffusion matrix for diffusing an error generated in image processing according to the present invention.

FIG. 7 is a block diagram of an image processing unit of the host computer according to the present invention.

FIG. 8 is a block diagram of a print control unit according to the first embodiment.

FIG. 9 is a diagram illustrating one-pass printing.

FIG. 10 is a diagram illustrating two-pass printing.

FIG. 11 is a diagram illustrating an example of a mask.

FIG. 12 is a diagram illustrating printing of four passes.

FIG. 13 is a diagram illustrating a configuration of an output buffer in each path.

FIG. 14 is a block diagram of a print control unit according to the third embodiment.

FIG. 15 is a diagram illustrating a configuration of a conversion table according to the third embodiment.

[Explanation of symbols]

 101 Host Computer 102 Image Processing Unit 103 Printer 104 Print Control Unit 201 CPU 212 ROM 214 Main Memory (RAM) 216 Display Controller 218 Display 220 Disk Controller 222 Hard Disk 224 Floppy Controller 226 Floppy Disk 228 Printer Controller 230 Printer 232 Keyboard controller 234 Keyboard 236 Mouse controller 238 Mouse 301 CPU 302 ROM 303 RAM 304 Input buffer 305 Output buffer 310 Color cartridge 311 Black cartridge 320 Print control unit 321 Head driver 322, 323 Motor driver 324 Carriage motor 325 Paper feed motor 32 Recording paper sensor 327 Ink sensor 330 Yellow head 331 Magenta head 332 Cyan head 333 Black head 340 Printer engine 701 Brightness / density conversion unit 702 Addition unit 703 Error processing unit 704 Error memory 705 Quantization unit 706 Print mode selection unit 707 ID information conversion Units 711 to 713 Representative color tables 1 to 3 801 Memory control unit 802 Input buffer 803 CMYK information conversion unit 804 to 806 Pattern tables 1 to 807 Output buffer control unit 808 Output buffer 809 Mode selection unit 1304 Pattern table

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/52 H04N 1/46 B

Claims (14)

[Claims] 1. An image processing method for converting an input color multivalued image into a number of tones that can be output by an image output device and outputting the image, wherein pixels of the input color multivalued image are output by the image output device. Converting the dot pattern pixels into ID information representing a representative color with a small number of bits, changing the number of bits of the ID information according to an output mode, And transmitting the ID information to a dot pattern and outputting the same. 2. A method of converting a pixel of an input color multi-valued image into a dot pattern pixel having a number of gradations that can be output by an image output device, wherein reproduced color data is output when a representative color of the dot pattern is output. 2. The image processing method according to claim 1, wherein an error between the input color multivalued image and pixel data of the input color multivalued image is obtained, and the obtained error is distributed to peripheral pixels at a predetermined ratio. 3. An image processing system comprising an image processing device and an image output device for converting an input color multi-valued image into a number of tones that can be output by an image output device and outputting the image. The processing device converts the pixels of the input color multivalued image into dot pattern pixels having the number of gradations that can be output by the image output device, and converts the dot pattern pixels into ID information representing a representative color having a small number of bits. Changing the number of bits of the ID information in an output mode, transmitting the ID information to the image output device, and converting the ID information into a dot pattern in the output mode and outputting the converted dot information. An image processing system characterized by the following. 4. An image processing apparatus for converting an input color multivalued image into a number of tones that can be output by an image output device and outputting the image, wherein pixels of the input color multivalued image are output by the image output device. Converting the dot pattern pixels into ID information representing a representative color with a small number of bits, changing the number of bits of the ID information according to an output mode, An image processing apparatus for transmitting an image to an image output apparatus. 5. When reproducing pixels of an input color multivalued image into dot pattern pixels having the number of tones that can be output by an image output device, reproduced color data when a representative color of the dot pattern is output. 4. The image processing system according to claim 3, wherein an error between the input color multi-valued image and pixel data of the input color multivalued image is obtained, and the obtained error is distributed to peripheral pixels at a predetermined ratio.
The image processing apparatus according to any one of the preceding claims. 6. An image output device for receiving and outputting ID information representing a representative color having a different number of bits for each output mode, comprising: an input buffer for storing received ID information; and an ID buffer read from the input buffer. An image output apparatus comprising: a conversion unit that converts the ID information into a dot pattern according to an output mode; and an output buffer that stores the dot pattern. 7. The image output apparatus according to claim 6, wherein said conversion means has a table storing said dot pattern corresponding to said ID information. 8. The image output apparatus according to claim 7, wherein the table is provided for each output mode, and the table is selected according to the output mode. 9. The table is provided with one table corresponding to the maximum bit of the ID information,
The image output device according to claim 7, wherein a dot pattern for the D information is shared. 10. The image output device according to claim 6, wherein the image output device is a printing device. 11. The image output apparatus according to claim 10, wherein said output mode corresponds to the number of passes to be printed. 12. The image output apparatus according to claim 11, wherein the capacity of the output buffer changes according to the printing pass, and the table is provided according to the change in the capacity. 13. A recording medium storing a program for performing a process of converting an input color multivalued image into a number of gradations that can be output by an image output device, wherein pixels of the input color multivalued image are converted by the image output device. Converting the dot pattern pixels into a dot pattern pixel having an outputable number of tones, converting the dot pattern pixel into ID information representing a representative color having a small number of bits, changing the number of bits of the ID information according to an output mode; A recording medium storing a program for performing a process of transmitting information to an image output device. 14. A recording medium storing a program for performing processing for receiving and outputting ID information representing a representative color having a different number of bits for each output mode, wherein: an input buffer for storing the received ID information; A conversion means for converting the ID information read out from the ID information into a dot pattern in an output mode, and an output buffer for storing the dot pattern, wherein a computer system is configured to store a program. Recording medium.