JPH09258940A - Color image data transfer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce communication data quantity without executing a special compression/expansion processing at the time of transferring color image data. SOLUTION: A host 11 discriminates whether the pixels are white or not based on data of cyan, Magenta, yellow and black for the respective pixels and transmits binary data to a printer control part 10 in the case of the white pixels. Data of cyan, Magenta, yellow and black are transmitted to the printer control part 10 when they are not white pixels. The printer control part 10 develops a picture based on the received data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image data transfer system suitable for transferring color image data from a host such as a personal computer (personal computer) to a printer.

[0002]

2. Description of the Related Art There are two known conventional methods for transferring color image data from a host such as a personal computer or a workstation to a printer such as a color laser printer or a color inkjet printer. First
In this method, the host side converts the image information into a page description language dedicated to the printer and sends it to the printer side, and the printer side analyzes the page description language, expands it into image information, and prints it out. Secondly, since the speed of personal computers and the like has increased in recent years, there is a method in which an image is developed on the host side and transmitted to the printer side, and the printer side prints out based on this image information.

[0003]

However, in the method in which the host sends the image data to the printer as in the second method, compared with the method in which the page description language is sent as in the first method. There is a problem that the throughput of the printer is reduced because the communication data is greatly increased. Further, there is a problem that the cost increases when a high speed communication line such as SCSI or network is used. Here, in order to solve the above-mentioned problem, a method of compressing image data on the host side and decompressing it on the printer side can be considered. In this case, a process of performing special compression and decompression on the host side and printer side Is needed, and as a result,
There is a problem of overhead.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a color image data transfer system capable of reducing the amount of communication data without performing special compression and expansion processing.

It is another object of the present invention to provide a color image data transfer system capable of reducing the capacity of the image memory on the printer side.

[0006]

In order to achieve the above object, the first means is to determine whether or not a pixel is white on the basis of cyan, magenta, yellow and black data for each pixel on the transmission side, If it is a white pixel, only binary data is transmitted to the receiving side, and if it is not a white pixel, cyan, magenta, yellow, and black data is transmitted, and the receiving side develops a color image based on this received data. It is characterized by doing.

The second means judges whether or not the gradation data values of cyan, magenta, yellow, and black are continuous for each pixel when the transmitting side is a non-white pixel in the first means. If the grayscale value of the pixel is the maximum value, the grayscale value is decremented by one and the maximum grayscale value is runlength coded. It is characterized in that it is transmitted as a control code shown, and the receiving side develops gradation data of each pixel based on this control code, the number of pixels and the gradation value.

In the third means, in the second means, the transmitting side sequentially transmits the cyan, magenta, yellow, and black gradation data of each pixel on a page-by-page basis, and the receiving side stores an image memory having a capacity of one color. It is characterized in that the gradation data of each color is developed line by line in page units to print each color in page units.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a color image data transfer system according to the present invention, FIG.
3 is an explanatory diagram showing a pixel data expanding method, FIG. 3 is an explanatory diagram showing a concrete example of the pixel data expanding method, FIG. 4 is an explanatory view showing a pixel address expanding method in FIG.
FIG. 5 is an explanatory diagram showing another specific example of the method of expanding pixel data, FIG. 6 is an explanatory diagram showing a communication sequence, FIGS. 7 and 8 are flowcharts for explaining transmission processing on the host side, and FIG. 9 is a printer. FIG. 10 is a flowchart for explaining the receiving process on the printer side, and FIG. 10 is an explanatory diagram showing the image developing process on the printer side.

In FIG. 1, the host 11 prints print data obtained by compressing color image data of each color of cyan (C), magenta (M), yellow (Y), and black (K) in a format described later, and a printer control unit. Send to 10. When the CPU 1 of the printer control unit 10 receives the print data transmitted from the host 11 via the host I / F 2, it stores C, M, and C on the image memory 4 having a capacity of one color.
Image data of each color of Y and K is sequentially developed page by page,
When the expansion is completed, the expanded image data is sequentially output page by page to the color printer 5 via the printer I / F 3 to perform printout.

The printer I / F 3 is provided with a line counter 6 for storing the number of lines whose output has been completed.
Based on the value of the line counter 6, the line data of the previous color is expanded on the image memory 4 so that the line data of the next color is not overwritten.

FIG. 2 shows C, M, and
An example of Y and K gradation data (8 bits) is shown. This data includes gradation number (= 256 = 0 to 255), pixel address (X, Y), and each gradation of C, M, Y, and K. It can be represented by data. In the host 11, first, the pixel address expansion is started from (0, 0), and in this case, as shown in FIG.
As shown in (d), any of C, M, Y, and K is "0".
For pixels that are not, the binary image flag is set. As a result, a white pixel can be represented by a binary image flag = 0, and therefore, the white pixel can be compressed by performing so-called run length coding.

Next, as shown in FIG. 2E, C, M, Y, and K data are expanded for each pixel address. In this case, if the gradation data has the maximum value (= 255), Set the value to "254". With this, "255"
The value of “11111111” = “FF” can be used as a control code or a print control code indicating that run length coding has been performed, as described later.

FIG. 3 shows an example of developing a character "image" consisting of color components of only C (= 128) and Y (= 64) as an example of a monochromatic binary image other than white on a white background. Can be represented by C and Y only (M = K =
0). Therefore, the host 11 expands the pixel address only for the pixel corresponding to the character "image" as shown in FIG. 4A, and then C, M, Y for this pixel as shown in FIG. 4B. , K data are combined.

FIG. 5 shows a case in which a figure "○" of C = M = Y = K = 64 is developed as another example of a binary image of a single color other than white on a white background, and in this case as well, The pixel address is developed only for the pixel corresponding to the figure "○", and the data of C, M, Y, K is combined with this pixel. Therefore, the pixels of this binary image can also be compressed by similarly run-length coding.

Next, the control sequence transmitted from the host 11 to the printer will be described with reference to FIG. Host 1
The format transmitted from 1 to the printer is made up of one or more fields, and one field is made up of 8 bits (= the number of gradations). First, “01” indicating the command as a page definition command, the number of pixels in the horizontal direction of one page, the number of pixels in the vertical direction, the number of gradations, the resolution, and the paper size are transferred.

Next, prior to the gradation data of C, M, Y, and K, "02" indicating the command as a binary data command indicating white, the horizontal direction bit number, and the vertical direction bit number are transferred. Binary image data is transferred.

Next, when the data other than "0" is set as the cyan gradation data, the cyan gradation data command "03" of one field is transmitted, and the cyan gradation value continues for 3 pixels or more. 2 if not
Pixel data is transmitted. In this case, when the gradation of the same value is continuous for 3 pixels or more, “FF” indicating the control code as the continuous definition control code, the continuous number (0 to 254) and the gradation data are transmitted.

As a result, when 255 pixels having the same value continue, 255 × 8 bits are compressed to 3 × 8 bits. Although the maximum gradation value "255" is changed to "254", the reproducibility of the printer engine 5 does not deteriorate the image. Note that the number of gradations is not limited to 256 = 8 bits, and may be multiple gradations such as 16 = 4 bits and 64 = 6 bits. In this case, the control code is "1".
111 "and" 111111 ".

Then, when the transmission of the cyan gradation data is completed, if the transmission data of other colors still remain, "FF" and "F" indicating the control code as the print control code.
The control code "01" indicating "F" and "continue" is transmitted,
On the other hand, when there is no remaining code, "F" indicating the control code is displayed.
The control code "01" indicating "F", "FF" and "end" is transmitted.

Hereinafter, magenta, yellow, and black are transmitted in the same format, and when transmission of all color data is completed, "FF" and "F" indicating control codes are displayed.
The print control code "01" indicating "F" and "end" is transmitted. Then, the print control code requests the printer to print and eject the paper. Further, as a result, even when all the C, M, Y, and K data are not received, only the received colors are printed.

Next, referring to FIGS. 7 and 8, the host 11
The transmission processing of will be described. The processes shown in FIGS. 7 and 8 are the processes after transferring all the binary image data in FIG. 6, and also show the transmission process for one color. First, a gradation data command (a cyan gradation data command “03” in the first process) is transmitted (step S1), and then the same value gradation data number N as the pixel address PIXEL is reset (PIXEL = 0, N = 0). ) (Step S2). Next, the binary image flag of that pixel is determined (step S3), and if the binary image flag is set, that is, if it is not a white pixel, step S3.
On the other hand, if the binary image flag is not set, that is, if the pixel is a white pixel, the process jumps to step S12.

In step S4, it is determined whether the same-value gradation data number N is "0", "1", or "2". And N =
If it is 0, the pixel value is set as the gradation data V0 (step S5), and the process proceeds to step S12. When N = 1, the pixel value is set as the gradation data V1, and the same value gradation data number N is incremented by 1 (step S6). V1 is transmitted and the same value gradation data number N is reset (steps S7 → S8),
Proceed to step S12. When N = 2, the pixel value is set as the gradation data V2, and the same-value gradation data number N is incremented by 1 (step S
9), and then if V1 = V2, grayscale data V0, V
1 and V2 are transmitted and the same-value gradation data number N is reset (steps S10 → S11), and the process proceeds to step S12.

In step S12, the pixel address is set to 1
By one, and then it is determined whether the pixel is the last address of one page (step S13), N
In the case of O, the process proceeds to step S14, while in the case of YES, the process proceeds to step S21 shown in FIG. Step S1
In step 4, it is determined whether N <3. If N <3, the process returns to step S3. On the other hand, if N <3 is not satisfied, step S3 is performed.
Proceed to 15. In step S15, the binary image flag of the pixel is determined. If the binary image flag is not set, the process returns to step S12, while if it is set, the process proceeds to step S16.

In step S16, it is determined whether the gradation data V0 = pixel value, and if YES, step S1.
7. If NO, on the other hand, if NO, the process branches to step S20. In step S17, the same-value gradation data number N is incremented by 1, and then it is determined whether N = 254 (step S18). If NO, the process directly returns to step S12, and if YES, control is performed. Code "F
F ”, the same-value gradation data number N and gradation data V0 are transmitted, and the same-value gradation data number N is reset (step S19), and the process returns to step S12. Step S
In the case of 20, the control code “FF” and the same value gradation data number N
And the gradation data V0 are transmitted, the same value gradation data number N is reset, and the process returns to step S3.

In step S21, it is determined whether or not N = 0. If YES, the process jumps to step S23. On the other hand, if NO, the control code "FF", the same-value gradation data number N, and gradation are set. Data V0 is transmitted (step S2
2), go to step S23. In step S23, C,
Judge whether all the data of M, Y, K has been transmitted,
In the case of NO, the control code "FF", the code "01" indicating "FF" and "continue" is transmitted (step S2).
4) Then, the process returns to step S1 and the data of the next color is transmitted. On the other hand, when the data of all colors is transmitted in step S23, the control code "FF", the code "01" indicating "FF" and "end" is transmitted (step S2).
5) Then, this transmission process is terminated.

Next, the gradation data receiving process on the printer side will be described with reference to FIG. Similarly in FIG. 9, 2 in FIG.
This is a process after receiving all the value image data, and first, when a gradation data command (a cyan gradation data command “03” in the first process) is received (step S3
1) The pixel address PIXEL is reset (step S32), and then the line counter is read (step S33). Here, the line counter of the output image is set in the register during printing, and it is monitored whether the output of the line of the color developed in the image is completed. Is not expanded.

In the subsequent step S34, if the development area is being output, the process returns to step S33. On the other hand, if the development area is not being output, the process proceeds to step S35. When the gradation data is received in step S35, the control code "F
If it is "F" (step S36), the process proceeds to step S37 and below if NO, and branches to step S38 and below if YES. In step S37, the same value gradation data number N is set to "1", and in step S4
Proceed to 1.

In step S38, a field of the same value gradation data number N following the control code "FF" is received. If the field is not the control code "FF" in the following step S39, the process proceeds to step S40 and the control code " If it is "FF", the process branches to step S46. In step S40, the gradation data of the succeeding field is received,
It proceeds to step S41.

In step S41, the binary flag of the pixel data is judged, and if it is a white pixel, the pixel address PIXEL is incremented by 1 (step S41).
42) and returns to step S41. On the other hand, step S41
If it is not a white pixel, the gradation data is set in the image memory 4 (step S43), and then the same value gradation data number N is decremented by 1 (step S43).
44). Next, in step S45, if the same-value gradation data number N is not "0", the process returns to step S42, while if it is "0", the process returns to step S33.

In step S46, the print control code is received. If the "continue" code is "01", that color is printed (step S48), and then the process returns to step S31 to receive the gradation data of the next color. I do. On the other hand, if the "end" code is "00" in step S46, that color is printed and the paper is ejected (step S49), and this receiving process is ended.

Image development and output parallel control of the printer will be described with reference to FIG. In FIG. 10, in the image memory 4 for one color, the cyan data starts to be developed from the 0th line to the last line, and the 0th to 2nd lines are output, and then the 0th to 2nd lines of magenta are output. The expanded state is shown. In this case, the image output control unit 1a (CP
U1) updates the line counter register 6 upon completion of the cyan data line output, and in this example, since three cyan lines are being output, "2" is set in the register.

The image development processing section 1b (CPU1)
Immediately starts the output of cyan data, and immediately expands the magenta data. In this example, since "2" is set in the register, it expands to the second line, and for the third line, the register value is "3". Will not be deployed until

[0034]

As described above, according to the first aspect of the invention, the transmitting side determines whether or not the pixel is white based on the cyan, magenta, yellow, and black data for each pixel, and the receiving side. In contrast, if it is a white pixel, only binary data is transmitted, and if it is not a white pixel, cyan,
Since magenta, yellow, and black data are sent and the receiving side develops a color image based on this received data, in the case of white pixels, cyan, magenta, yellow, and black data are not sent, and there are many white background colors. It is possible to reduce the communication data amount without performing special compression and decompression processing when transmitting a document.

According to the second aspect of the invention, when the transmitting side is a non-white pixel, it is judged whether or not the values of the respective gradation data of cyan, magenta, yellow and black are continuous for each pixel, and they are continuous. In this case, the number of pixels is run-length encoded, and when the tone value of the pixel is the maximum value, the tone value is decremented by 1 and the maximum tone value is run-length encoded. Since it is transmitted as a control code and the receiving side expands the gradation data of each pixel based on this control code, the number of pixels and the gradation value, it is possible to reduce the communication data amount without performing special compression and expansion processing. You can

According to the third aspect of the invention, the transmitting side sequentially transmits the cyan, magenta, yellow, and black gradation data of each pixel in page units, and the receiving side stores each color on the image memory having a capacity of one color. Since each color is printed page by page by expanding the gradation data of (1) for each line on a page basis, the capacity of the image memory on the printer side can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a color image data transfer system according to the present invention.

FIG. 2 is an explanatory diagram showing a method of expanding pixel data.

FIG. 3 is an explanatory diagram showing a specific example of a method of expanding pixel data.

FIG. 4 is an explanatory diagram showing a method of expanding a pixel address in FIG.

FIG. 5 is an explanatory diagram showing another specific example of the pixel data expanding method.

FIG. 6 is an explanatory diagram showing a communication sequence.

FIG. 7 is a flowchart for explaining a transmission process on the host side.

FIG. 8 is a flowchart for explaining a transmission process on the host side.

FIG. 9 is a flowchart illustrating a receiving process on the printer side.

FIG. 10 is an explanatory diagram illustrating image expansion processing on the printer side.

[Explanation of symbols]

 1 CPU 4 Image Memory 5 Printer 6 Line Counter 10 Printer Control Unit

Claims (3)

[Claims] 1. The transmitting side determines whether or not the pixel is white based on the cyan, magenta, yellow, and black data for each pixel, and when the pixel is a white pixel, only the binary data is transmitted to the receiving side. If it is not a white pixel, cyan, magenta, yellow, and black data are transmitted, and the receiving side develops a color image based on this received data. 2. When the transmitting side has non-white pixels, it is judged whether or not the values of each gradation data of cyan, magenta, yellow, and black are continuous for each pixel, and if they are continuous, the number of pixels is determined by the run length. While encoding, if the gradation value of the pixel is the maximum value, set the gradation value to 1
Decrementing and transmitting the maximum grayscale value as a control code indicating run-length coding, and the receiving side developing the grayscale data of each pixel based on this control code, the number of pixels, and the grayscale value. The color image data transfer method according to claim 1, wherein 3. The transmission side sequentially transmits the gradation data of cyan, magenta, yellow, and black of each pixel in page units, and the reception side stores the gradation data of each color in page units on an image memory having a capacity of one color. 3. The printing of each color is performed page by page by expanding each line.
Color image data transfer method described.