JPH1134400A - Color printing method - Google Patents

Abstract

(57) [Problem] To reduce the amount of color image information given to a color printer without deteriorating the expressiveness of colors represented by gradation. SOLUTION: An area gradation circuit 501 of a color printer control device includes color image information 500 received from a host device.
A color extractor 511 for extracting a tone value 503 from the sub-scanning direction raster coordinates 507 and the main scanning direction dot coordinates 50
And a dither matrix 506 that outputs a boundary value 504 corresponding to 8 and an EVEN raster comparison / output that outputs a limited gradation value 505 from the gradation value 503 and the boundary value 504.
Arithmetic unit 509, ODD raster comparison / arithmetic unit 510
And whether or not the raster coordinate 507 in the sub-scanning direction is EVEN (second raster) or ODD (first raster).
Operation unit 509, selector 5 for selecting comparison / operation unit 510
12 are generated, and tone values of a plurality of pixels on the color printer apparatus side are generated from the data of one pixel of the color image information 500.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printing technique, and more particularly to a technique effective when applied to color printing using a color printer having a limited gradation output.

[0002]

2. Description of the Related Art A conventional technique is intended to complement a lack of gradation output of a color printer for a color printer in which gradation output is insufficient to perform full-color printing.
Pseudo gradation processing such as area gradation and error diffusion is performed, and the number of gradations required for full color printing is prepared to perform full color printing. In this case, the color image information received from the host device corresponds to the resolution of the color printer. That is, the higher-level device generates color image data corresponding to the resolution of the subordinate color printer and outputs the color image data to the color printer.

[0003] As such a conventional image processing technique, for example, Japanese Patent Publication No. 7-38683 discloses a method of obtaining a change pattern of a recording area in one pixel according to the density level of an input image signal. There is disclosed a technique in which the number of stages can be freely selected according to the pulse width of a periodic signal selectively generated corresponding to each of a plurality of modes.

Japanese Patent Application Laid-Open No. Hei 4-345366 discloses that image data represented by multi-valued gradation levels is converted into pixel data of a high-density region and pixel data of a low-density region for each pixel using a predetermined density level as a threshold. There is disclosed a technique in which pixel data in a high-density region is output as it is, and pixel data in a low-density region is output after performing area gradation processing.

Further, Japanese Patent Application Laid-Open No. Hei 5-212596 discloses a technique in which when a binary pixel is included in a pixel having a multi-level image resolution, the resolution of the multi-valued pixel of interest is increased and output. ing.

[0006]

However, even for a color printer with a gradation output of, for example, about 8 gradations, color image information composed of 256 gradations of color information required by pseudo gradation processing is created. Therefore, the amount of information of the color image information is large, and the time required to create the color image information in the host device and the time to transfer the color image information to the color printer control device are required. A large memory capacity for storage was also required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color printing technique capable of reducing the amount of color image information given to a color printer without deteriorating the expressiveness of colors represented by gradation. is there.

Another object of the present invention is to provide a color printer in which color image information generated by a higher-level device is supplied to a subordinate color printer to perform the color image information creation time in the higher-level device and the color image information. It is an object of the present invention to provide a color printing technique capable of reducing a transfer time of color image information to a printer and a memory capacity for handling the color image information.

Another object of the present invention is to handle color image information of various resolutions different from the resolution of a color printer, so that the amount of color image information can be reduced without lowering the expressiveness of colors at a low resolution. It is an object of the present invention to improve the performance by reducing the size, to enable high-definition print output at a high resolution, and to realize efficient and various color printing according to the purpose.

[0010]

According to the present invention, color image information is created at a low resolution of 1 / n (n = integer) of the resolution of a color printer, and the low-resolution color image information is generated by a color printer control device. Is converted to a limited gradation value from the color information of one pixel of the color image information to a limited gradation value of two or more pixels to be sent to the color printer, Send and color print.

For example, in the case of a color printer having a gradation output of about 8 gradations, it is possible to output 16 gradations with two pixels, so that the resolution of the color printer in both the main scanning direction and the sub-scanning direction is obtained. When gradation output is performed to a color printer with respect to color image information having a resolution of 1/2, output of 32 gradations with four pixels is possible. That is, 8 pixels per pixel
For gradation output, 128 gradations per color (= 8 gradation output × 16 gradation dither matrix) in combination with area gradation processing using a 4 × 4 16 gradation dither matrix, 3
Approximately 2 million primary colors (= 128 gradations x 128 gradations x 12
Similarly to the case of performing the color expression of (8 gradations), when the output of 32 gradations with 4 pixels and the area gradation processing using the dither matrix of 2 × 2 4 gradations are used together, 128 per color is used. Gray scale (= 32 gray scale output × 4 gray scale dither matrix), approximately two million colors can be expressed with three primary colors.

As described above, color printing is performed from color image information of a low resolution of 1 / n (n = integer) of the resolution of the color printer without deteriorating the expressiveness of colors represented by gradation. By reducing the amount of color image information, the time required to create color image information in the host device,
The transfer time of color image information to the color printer control device can be reduced, and the memory in the color printer control device can be reduced.

In the present invention, the host device has a function of creating color image information with two or more resolutions and a function of instructing the color printer control device of the resolution of the created color image information. With
In the color printer control device, the function of converting the color information of one pixel of the color image information into the limited gradation value of two or three or more pixels to be sent to the color printer is changed to two or three or more resolutions. The color information for one pixel of the color image information is converted into limited gradation values of one or two or more pixels according to the resolution specified by the host device, and sent to a color printer; Color printing may be performed.

[0014]

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

FIG. 1 is a conceptual diagram showing an example of the configuration of an information processing system in which a color printing method according to an embodiment of the present invention is implemented.

The information processing system according to the present embodiment includes, for example, an upper-level device 100 including a general-purpose large-sized computer, a workstation, a personal computer, and the like, and a subordinate color printer control device 101 and a color printer device 102. The main configuration of the color printer control device 101 is shown. The color printer device 102 is, for example, a color laser printer.
The color printer control device 101 fetches the color image information received from the higher-level device 100 into the reception buffer 103, analyzes this in the MPU unit 104, and then obtains the gradation values of yellow, magenta, cyan, and black (= 0 to 255). )
And the limited gradation value (first gradation) for sending color information composed of gradation values (= 0 to 255) of each color to the color printer 102 by the area gradation circuit 105 ), And the video signal transmitting circuit 106 converts the limited gradation value into a video signal and transmits the video signal to the color printer 102.

It is assumed that the above-mentioned limited gradation value is sent to the color printer 102 according to the length of the ON / OFF level of the video signal as an example. That is, for example, as shown in FIG.
0 ns, limited tone values excluding 0 from 0 to 8
Assuming that the gradation is ON, the ON time of the video signal is 0, 10, 2
OFF at 0, 30, 40, 50, 60, 70, 80 ns
Time is 80, 70, 60, 50, 40, 30, 2, respectively
Any one of 0, 10, and 0 ns is sent to the color printer 102 as a video signal for one pixel. The color printer 102 receives a video signal from the color printer controller 101, attaches toner corresponding to the ON time of the video signal, and prints on paper.

That is, in FIG. 2, the waveforms 201 to 208 of the video signal correspond to one pixel (allocation time 80n).
In the case where eight gradations are expressed by the video data of s),
ON time is 10 ns to 80 ns and OFF time is 70 ns
5 to 0 ns, waveforms are shown. In the case where toner is attached when the video signal is ON, a waveform 20 is shown.
The gradation changes so that 1 is the lightest and waveform 208 is the darkest.

Similarly, waveforms 209 to 216 in FIG.
Illustrates a case where the same eight gradations are expressed by video data for two pixels (allocation time 160 ns). In this case, the waveforms 209 to 216 have ON times of 90 ns to 1
The waveform examples in the case of 60 ns and the OFF time of each of 70 ns to 0 ns are shown. When toner is applied when the video signal is ON, the waveform 209 is the lightest and the waveform 2
At 16, the gradation changes so as to be the darkest.

In each example of the waveforms 201 to 216 in FIG. 2, for simplicity, the ON time of the video signal is illustrated left-justified, but every 10 ns within the assigned time of each pixel. It goes without saying that a waveform that is almost uniformly dispersed may be generated and used.

FIG. 3 is a conceptual diagram showing an example of the configuration of the color printer device 102 of the present embodiment. The color printer 102 according to the present embodiment includes a photosensitive belt 300 traveling in the sub-scanning direction and a laser beam 3 in the width direction (main scanning direction) of the photosensitive belt 300 traveling in the sub-scanning direction.
06a and a laser 306 for forming an electrostatic latent image (latent image page 305) and an electrostatic latent image formed on the photoreceptor belt 300 are selectively adhered with color toners of respective primary colors and developed. A developing unit 301 serving as a development page 304 and a developed electrostatic latent image (development page 304) are transferred as a transfer page 303 and the transfer page 303
07, and the like.

The color printer 102 receives a video signal for each color and forms a latent image (latent image page 305) on the photosensitive belt 300 by scanning with a laser beam 306a as shown in FIG. A development page 304 is created by attaching the corresponding color toner by 301, and the toner (development page 304) on the photosensitive belt 300 is transferred to the transfer drum 302 as a transfer page 303. This is repeated for four colors, and after toner of four colors is attached to the transfer drum 302, the toner is transferred to the paper 307 and printed. The color information of the color image information received from the host device 100 may be composed of three primary colors of yellow, magenta and cyan, or may be composed of four primary colors of yellow, magenta, cyan and black. Good or red (red),
It may be composed of three primary colors of green (green) and blue (blue). When the color information of the color image information is the three primary colors of yellow, magenta, and cyan, the color printer control device 101 outputs four colors of yellow, magenta, cyan, and black.
When the color information of the color image information is three primary colors of red (red), green (green), and blue (blue), the color printer control device 101 It is assumed that the image data is converted into three primary colors of yellow, magenta, and cyan and four primary colors of yellow, magenta, cyan, and black, and output to the color printer 102.

Next, the color printer 102 in both the main scanning direction and the sub-scanning direction will be described with reference to FIGS.
An embodiment will be described in the case where color image information having half the resolution of the color image information is output to the color printer 102 as gradations.

As illustrated in FIG. 5, the host device 100
The color printer control device 101 receives the color image information 500 having a resolution (second resolution: for example, 300 dpi) which is 解像度 of the resolution (first resolution: for example, 600 dpi) of the color printer device 102 created in step (1). The color information of each color including the gradation values (second gradation values) of .about.
02 is converted to a limited gradation value (first gradation value: for example, a gradation value of 0 to 8) for transmission to the video signal 02, and the limited gradation value is converted into a video signal by the video signal transmission circuit 502. The data is converted and sent to the color printer 102.

Here, the area gradation circuit will be described first. The gradation expression is 128 gradations for each color and about 20 for three primary colors.
It enables color representation of 10,000 colors.

For comparison, FIG. 4 shows color image information 40 having the same resolution (for example, 600 dpi) as that of the color printer 102 (for example, 600 dpi).
The color printer device 10 with the gradation value 405 limited to 0
2 shows an example of the area gradation circuit 401 when outputting to 2.
The gradation value output to the color printer 102 is 0.
8 to 8 except for 0 to 8. In the area gradation circuit 401 of 8 gradation output, 128 gradations are realized by the area gradation by the dither matrix 407 of 4 × 4 16 gradations and the 8 gradation output. Output to the printer device 102. Specifically, for example, from the color information of the color image information 400, for example, a yellow gradation value 40
3 of the boundary value 404 defined by the dither matrix 407 and a value corresponding to the raster coordinates 408 in the sub-scanning direction and the dot coordinates 409 in the main-scanning direction.
Comparing by the arithmetic unit 406, when the boundary value 404 ≧ the gradation value 403, “0” is output for the limited gradation value 405, and when the boundary value 404 <the gradation value 403, If (gradation value 403-boundary value 404) <8, '(gradation value 403-boundary value 404)' is output for the limited gradation value 405, and (gradation value 403-boundary value 404). If the value 404) ≧ 8, “8” is output for the limited gradation value 405.

On the other hand, FIG.
Image information 500 having a resolution (for example, 300 dpi) which is half the resolution (for example, 600 dpi) of
Is an example of the area gradation circuit 501 in the case where is output to the color printer device 102 with a limited gradation value.

The area gradation circuit 501 is a color extractor 511 for extracting a gradation value 503 from color information according to color selection information from the color image information 500 coming from the host device 100.
A dither matrix 506 that outputs a boundary value 504 corresponding to the raster coordinates 507 in the sub-scanning direction and the dot coordinates 508 in the main scanning direction, and a gradation value 503 and a boundary value 50
4, the EVEN raster comparator / operator 509 and the ODD raster comparator / operator 510 that output the gradation values 505 limited by the determination conditions described below, and the input sub-scanning direction raster coordinates 507 A comparison / calculator 509 and a selector 512 for selecting the comparison / calculator 510 based on whether EVEN (second raster) or ODD (first raster) are provided.

In this case, the gradation value (first gradation value) to be output to the color printer device 102 is 16 gradations from 0 to 16 excluding 0 in the main scanning direction. In the sub-scanning direction, two scans (EVEN raster / ODD raster) are output to the color printer device 102 based on information of one scan of the color image information 500 having a half resolution. This 2
When the scanning amount is output to the color printer device 102, the first scanning (ODD raster) and the second scanning (EVEN raster) are output in a total of 32 tones, and a dither matrix 506 of 2 × 2 and 4 tones is used. 128 in combination with area gradation
Realize gradation. EV in this embodiment as described above
FIG. 7 shows how the resolution / gradation value is converted by the comparison / calculation unit 509 for the EN raster and the comparison / calculation unit 510 for the ODD raster.

More specifically, for example, a tone value 503 of yellow is obtained from the color information of the color image information 500 and is compared with a boundary value 504 defined by a dither matrix 506. In this case, “0” is output for both the limited gradation value 505 of the first scan and the limited gradation value 505 of the second scan, and when the boundary value 504 <the gradation value 503, If (gradation value 503-boundary value 504) <16, then '(gradation value 503-boundary value 504)' is output for the limited gradation value 505 in the first scan, and two scans are performed. '0' is output for the gradation value 505 limited to the eyes.

If 16 ≦ (gradation value 503−boundary value 504) <32, “16” is output for the limited gradation value 505 in the first scan, and the limited floor value in the second scan. Adjustment value 505
With respect to '(gradation value 503-boundary value 504) -1
6 'is output.

If (gradation value 503−boundary value 504) ≧ 32, “16” is set for both the limited gradation value 505 in the first scan and the limited gradation value 505 in the second scan. Is output.

With respect to such an area gray scale output result,
In the video signal transmission circuit 502, the limited gradation value is 0,
, 15, and 16, the ON time of the video signal is 0, 10, 20,.
FF time is 160, 150,..., 20, 10,
0 ns (see FIG. 2). As described above, when the color image information 500 having half the resolution of the color printer 102 is output to the color printer 102 with a limited gradation value, the area gradation circuit 501 outputs four times the gradation. By performing output and 1/4 area gradation processing, the color printer 10
Compared to the case where color image information having the resolution of 2 is output to the color printer device 102 with limited gradation values, color printing can be performed without lowering the expressiveness of colors represented by gradation.

As described above, according to the present embodiment, color printing is performed without deteriorating the expressive power of colors represented by gradation, and the amount of color image information 500 is reduced to reduce the amount of information. Color image information 500 in the device 100
And the transfer time of the color image information 500 to the color printer control device 101 can be reduced, and the memory capacity of the reception buffer 103 and the like in the color printer control device 101 can be reduced. For example, the information amount of the color image information 500 having a resolution of １ ／ in both the main scanning direction and the sub-scanning direction with respect to the resolution of the color printer device 102 is the color amount of the color image information of the resolution of the color printer device 102. It becomes 1/4 of the image information.

FIG. 6 shows color image information having the same resolution as that of the color printer 602 (for example, 600 dpi) in a limited gradation value.
02 and the resolution (for example, 600 dp) of the color printer 602
i) Color image information having a half resolution (for example, 300 dpi) with a limited gradation value
2 is an example of a color printer control device 601 provided with two area gradation circuits, that is, an area gradation circuit 606 for outputting to the area 02.

That is, the color image information received from the host device 600 to the color printer control device 601 is held in the reception buffer 603, and is stored in the M buffer according to the resolution.
A selection circuit 607 controlled by the PU unit 608 selectively inputs one of the two area grayscale circuits 604 and 606 and selects one of the area grayscale circuit 604 and the area grayscale circuit 606. The output from the color printer control device 60 is transmitted via a video signal transmitting circuit 605.
1 is output to the color printer device 602 under the control of the printer 1. In this case, as a method of instructing a difference in resolution of color image information input from the higher-level device 600 to the color printer control device 601, a method using an interface (not shown) provided between the two, or a higher-level device 100 For example, a means such as a method of analyzing and determining the resolution identification information embedded in the color image information by the color printer control device 601 can be used.

As described above, the area gradation circuit 604 and the area gradation circuit 606 for processing color image information of two resolutions are provided in the color printer control device 601, and the resolution of the color image information transmitted from the host device 600 is adjusted. By providing the instruction means, the selection circuit 607 selects one of the area gradation circuit 604 and the area gradation circuit 606 in accordance with the instruction from the host device 600, so that color image information of two different resolutions can be handled. it can. As a result, at low resolution, performance can be improved by reducing the amount of color image information without lowering the expressiveness of colors,
At high resolution, high-definition print output can be performed, so that efficient color printing according to the purpose can be performed.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof. Needless to say, there is.

[0039]

According to the color printing method of the present invention, it is possible to reduce the amount of color image information given to a color printer without deteriorating the expressiveness of colors represented by gradation. Is obtained.

According to the color printing method of the present invention,
When performing color printing by giving the color image information generated by the higher-level device to the subordinate color printer, the time required to create the color image information in the higher-level device, and the time required to transfer the color image information to the color printer, In addition, the memory capacity for handling color image information can be reduced.

According to the color printing method of the present invention,
By handling color image information of various resolutions different from the resolution of the color printer, it is possible to improve the performance by reducing the amount of color image information without lowering the color representation at low resolution, With the resolution, it is possible to obtain a high-definition print output, and to achieve an effect of realizing efficient and diverse color printing according to the purpose.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an example of a configuration of an information processing system in which a color printing method according to an embodiment of the present invention is implemented.

FIG. 2 is a timing chart showing an example of the operation of the color printing method according to the embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating an example of a configuration of a color printer in an information processing system in which a color printing method according to an embodiment of the present invention is performed.

FIG. 4 is a conceptual diagram illustrating an example of a configuration of an area gradation circuit that performs gradation value conversion at the same resolution as input color image information.

FIG. 5 shows an example of a configuration of an area gradation circuit for converting a gradation value to a resolution larger than the resolution of input color image information in order to realize a color printing method according to an embodiment of the present invention. FIG.

FIG. 6 illustrates an example of a configuration of an area gradation circuit that performs gradation value conversion according to input color image information of different resolutions in order to realize a color printing method according to an embodiment of the present invention. FIG.

FIG. 7 is a conceptual diagram illustrating an example of an operation of the color printing method according to the embodiment of the present invention.

[Explanation of symbols]

100: host device, 101: color printer control device,
102: color printer device, 103: reception buffer,
104: MPU unit, 105: area gradation circuit, 106: video signal transmission circuit, 300: photoreceptor belt, 301: developing unit, 302: transfer drum, 303: transfer page, 30
4 development page, 305 latent image page, 306 laser, 306a laser light, 307 paper, 400 color image information, 401 area gradation circuit, 402 video signal transmission circuit, 403 gradation value, 404... Boundary value, 405
... Gradation value, 406... Comparison / calculator, 407... Dither matrix, 408... Sub-scanning direction raster coordinates, 409... Main scanning direction dot coordinates, 500.
... area gradation circuit, 502 ... video signal transmission circuit, 503
... gradation value, 504 ... boundary value, 505 ... gradation value, 506 ...
Dither matrix, 507... Raster coordinates in the sub-scanning direction,
508: dot coordinates in the main scanning direction, 509: comparison / calculator, 510: comparison / calculator, 511: color extractor, 512
... selector, 600: host device, 601: color printer control device, 602: color printer device, 603: reception buffer, 604: area gradation circuit, 605: video signal transmission circuit, 606: area gradation circuit, 607 Selection circuit,
608: MPU unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Okada 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Inside Hitachi Systems Office Systems Division (72) Inventor Yutaka Nakagawa 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Hitachi, Ltd. Manufacturing Office System Division

Claims (1)

[Claims] 1. A method according to claim 1, wherein a gradation is given to each of the plurality of primary colors.
A color printing method using a color printer in which gradation output at the time of printing at a resolution of the first gradation value is limited to a first gradation value. The color is adjusted so that at least one of the resolutions in the main scanning direction and the sub-scanning direction is a second resolution 1 / n (n is an integer of 2 or more) of the first resolution of the color printer. Image information is created, and from the color information of one pixel of the second resolution of the color image information,
A color printing method, comprising: converting the two or more pixels at the first resolution of the color printer into the first gradation values, sending the converted values to the color printer, and performing color printing.