CN1301859C - Table-printing machine system and method with halftone monocoloure treatment - Google Patents

Abstract

The present invention proposes a printer system with halftone monochromatic processing and a method. The printed image is composed of a pixel of a two-dimensional array and is arranged in the way of a plurality of column direction pixels. The printer system comprises an adder, a critical value device and an error decision device, wherein the first input end of the summator receives a pixel to be printed; the second input end receives a feedback error signal in order to generate a correction pixel; the critical value device is coupled to the adder; when a correction pixel value exceeds a preset critical value, a signal for printing the pixel is generated; when the correction pixel value does not exceeds the preset critical value, a signal without the need of printing the pixel is generated; the error decision device generates a feedback error signal according to the signals generated by the critical value device, the correction pixel and previous pixel printing information.

Description

Has the monochromatic printer system and method for handling of halftoning

Technical field

The invention relates to the technical field of printer, refer to a kind of monochromatic printer system and method for handling of halftoning that has especially.

Background technology

On real work of prining with printer, because the resolution of human eye is not high, if a group point dense arrangement is arranged on a small size, can't differentiate the difference of indivedual points at human eye, put integrally formed average reflectance and can only experience these, therefore as long as the density of this group of control point can form different shade of gray in the process of prining.The general technology of halftoning (half-tone) of using decides indivedual positions of putting in this group point off density, can be to the unjoyful phenomenon of human eye in the picture to reach default shade of gray and to reduce.The technology of halftoning is trembled look (Dithering) and two kinds of methods of error diffusion (Error diffusion).

The main meaning of Dithering method is with different GTG values, represents the corresponding GTG value of each pattern with corresponding one fixing pattern (Pattern).As shown in Figure 1,5 corresponding respectively GTG values of pattern are 0/4,1/4,2/4,3/4 and 4/4.The benefit of Dithering method is simple, also is easier to hardware and changes into circuit.Yet picture has fixing pattern (Pattern) effect, and can form different pattern effects according to selected pattern, and the unjoyful phenomenon of pair human eye is arranged easily.

The technology of another kind of halftoning then is an Error diffusion method, and compared to the Dithering method, the figure that utilizes the method to print does not have the Pattern effect, can produce image preferably to human eye.The notion of Error diffusion is because the GTG of prining has only two rank, so if the GTG of source image surpasses two rank, then can't produce extra GTG, yet the difference (Error) of source image every bit and actual GTG of prining (2 rank) can be diffused into adjacent grid, near adjacent ink dot so utilizing, the approaching GTG of image visually can obtain and originate.As shown in Figure 2, in the pixel that the error diffusion of pixel 0 is extremely contiguous, wherein, h1, h2 ..., h12={7/48,5/48,3/48,5/48,7/48,5/48,3/48,1/48,3/48,5/48,3/48,1/43}.

The system architecture of traditional E rror diffusion as shown in Figure 3, the GTG value of X representative input raw video pixel, its gray scale variation surpasses two rank, the B representative exports the GTG value of printer to, its GTG only has two rank (dispute China ink and not ink-jet).Because the grey exponent number of input image is many than the grey exponent number of image output, therefore can't find out man-to-man corresponding relation.This critical value generally is set at half of input image pixel maximum gray value, can determine to export to the GTG value B of printer thus.Yet it is huge all can to produce error between output each time and the input, therefore need be with this error diffusion in the image pixel of input next time.This error E is feedback to the image pixel of input next time via a filter.Repeat above step so again, can obtain the print image good than the Dithering method.But traditional Error diffusion system architecture is not considered the characteristic of actual output device, the for example size of ink-jet ink dot and shape, this not only can cause the waste of ink, can't be printd accurately simultaneously GTG value and backing up error, and influence the quality of prining.Therefore, the monochromatic processing method of the halftoning of known printer system still has many disappearances and gives improved necessity.

Summary of the invention

The object of the present invention is to provide a kind of monochromatic printer system and method for handling of halftoning that has, with the problem of avoiding known halftoning ink that monochrome technology is produced to waste, and obtain to print accurately GTG value and back coupling error, increase the quality of prining.

According to a characteristic of the present invention, a kind of monochromatic printer system that handles of halftoning that has is proposed, the image that this printer system is printd is made up of the pixel of a two-dimensional array, wherein, (i j) is listed as the capable pixel of j for this image i, and this printer system comprises:

One updating device, its first input end in order to receive this printer system transmit the pixel desiring to print (i, j), its second input is in order to receive an error signal of feedbacking, revise pixel (i, j+1), (i+1, j-1), (i+1, j), (i+1, value j+1);

One critical value device is coupled to this updating device, when this pixel (i, value j) surpasses a predetermined critical value and then produces a signal of prining this pixel, when this pixel (i, value j) surpasses this predetermined critical value. then produce a signal of not prining this pixel;

One error determination device, and the signal that is produced according to this critical value device, pixel (i, the information of value j) and the pixel value of before having printd is to produce the error signal of this back coupling; And

One filter, its input are coupled to the error signal that this error determination device is produced, and its output is connected to second input of this updating device.

Wherein this error determination device is that (i, j) information of the value and the previous pixel value of prining produces the error signal of this back coupling with lookup table mode for the signal that produced according to this critical value device, pixel.

According to another characteristic of the present invention, propose a kind ofly in the print method of halftoning monochrome of printer system, the image that this printer system is printd is made up of the pixel of a two-dimensional array, wherein, (i j) is listed as the capable pixel of j for this image i, and this method comprises the following steps:

One input step transmits the pixel desiring to print (i, value j), and receive an error signal of feedbacking in order to receive this printer system, revise pixel (i, j+1), (i+1, j-1), (i+1, j), (i+1, j+1) value repeats above process, up to finishing whole image processing;

One deciding step, when this pixel (i, j) value surpasses a predetermined critical value and then produces a signal of prining this pixel, when this pixel (i, j) value surpasses this critical value of being scheduled to and then produces a signal of not prining this pixel;

One error produces step, according to signal that this deciding step produced, pixel (i, j) information of the value and the previous pixel value of prining is to produce the error signal of this back coupling;

One filter step produces the error signal that step produces with error and carries out filtering, to produce the error signal of back coupling required in the input step.

Wherein this error produces step (i, j) value reaches the information of the pixel value of before having printd, and produces the error signal of this back coupling with lookup table mode according to signal, this pixel that this deciding step produced.

Description of drawings

Fig. 1 is the known schematic diagram of trembling the pattern (Pattern) of look (Dithering) method.

Fig. 2 is the schematic diagram of known error diffusion (Error diffusion).

Fig. 3 is the calcspar of known error diffusion system.

Fig. 4 has the monochromatic printer system block diagrams of handling of halftoning for the present invention is a kind of.

Fig. 5 is the schematic diagram of the monochromatic overlapping situation of ink dot of prining.

Fig. 6 is the print schematic diagram of ink dot error correction of monochrome of the present invention.

Fig. 7 is the monochrome of the present invention in addition schematic diagram of error correction of ink dot of prining.

Fig. 8 has the round-off error table of the monochromatic printer system that handles of halftoning for the present invention is a kind of.

The specific embodiment

Fig. 4 shows a kind of monochromatic printer system block diagrams of handling of halftoning that has of the present invention, the image 440 that this printer system printd is made up of the pixel 450 of a two-dimensional array, wherein, (i j) 450 is listed as the capable pixel of j for this image 440 i to pixel.Indicate the pixel value of pixel for before having handled of B1, B2, B3 and B4, (i, relative position relation j) as shown in Figure 4 for itself and pixel.

This printer system comprises a updating device 400, a critical value device 410, an error determination device 420 and a filter 430.The first input end of this updating device 400 transmits the pixel (i that desires to print in order to receive this printer system, j) value P (i, j) (be the pixel value of existing processing), its second input is in order to receive an error signal of feedbacking, with revise pixel (i, j+1), (i+1, j-1), (i+1, j), (i+1, j+1) value.In present embodiment, pixel (i, j) handle via updating device 400 after, error diffusion to pixel to be processed later on (i, j+1), (i+1, j-1), (i+1, j), (i+1, j+1).

This critical value device 410 is coupled to this updating device 400, as pixel (i, j) the value P (i of position, j) surpass a predetermined critical value and then produce this picture element signal of prining, as pixel (i, j) (i j) surpasses this predetermined critical value and then produces a signal of not prining this pixel the value P of position, represents with B0 respectively via signals that these critical value device 410 backs are produced.

This error determination device 420 is printd now according to this critical value device 410, and (i, j) (i j) produces an error signal E to the value P of position for the value of pixel B 0 and previous print pixel B 1, B2, B3, B4 and pixel.The input of this filter 430 is coupled to the error signal E that this error determination device 420 is produced, its output is connected to second input of this updating device 400, produce an error signal FE who feedbacks, revise pixel (i with this, j+1), (i+1, j-1), (i+1, j), (i+1, value j+1).

In the printer system of reality, the ink dot of being printd not is square but approaching circular.Because the ink dot of being printd needs and will fill up fully in the grid, otherwise can produce the unjoyful phenomenon of human eye.For reaching the requirement of filling up fully in the grid, the diameter of the ink dot that forms will be than the diagonal angle line length of grid.The diameter of supposing ink dot is β with the ratio of the diagonal angle line length of grid, because this ink dot has the subregion to fall within outside the grid, if another ink dot is arranged near the grid, then as shown in Figure 5, these two ink dots have overlapping γ situation and produce.How much mathematics of utilization can fall within ink dot grid outer area proportion and the shared grid area ratio of overlapping area and draw following equation:

$\mathrm{\α}=\frac{1}{4}\sqrt{{2\mathrm{\ρ}}^2-1}+\frac{{\mathrm{\ρ}}^2}{2}{\sin }^{-1}\left(\frac{1}{\sqrt{2}\mathrm{\ρ}}\right)-\frac{1}{2}$

$\mathrm{\β}=\frac{{\mathrm{\π\ρ}}^2}{8}-\frac{{\mathrm{\ρ}}^2}{2}{\sin }^{-1}\left(\frac{1}{\sqrt{2}\mathrm{\ρ}}\right)-\frac{1}{4}\sqrt{{2\mathrm{\ρ}}^2-1}+\frac{1}{4}---\left(1\right)$

$\mathrm{\γ}=\frac{{\mathrm{\ρ}}^2}{2}{\sin }^{-1}\left(\sqrt{\frac{{\mathrm{\ρ}}^2-1}{{\mathrm{\ρ}}^2}}\right)-\frac{1}{2}\sqrt{{\mathrm{\ρ}}^2-1}-\mathrm{\β}$

Measure the ink droplet that a printer is printd via reality, can obtain ρ=1.25=＞α=33%, β=3%, γ=10% is so the virgin folded effect that is caused of ink dot can not be ignored.

Do not consider the size and the shape of ink-jet point in known Error diffusion framework, then the error that is produced is irrelevant with ink dot on every side.Yet actual conditions are color ranges that ink dot on every side can influence the existing ink dot of prining.Under the ink dot influence around, even the not ink-jet of position of this existing ink dot of prining (B0=0) still has the GTG composition and exists.Therefore when calculating the error of the existing ink dot of prining, still ink dot on every side need be taken into account.As shown in Figure 6, B1=B2=B3=B4=1 has finished and has printd, and the pixel of existing processing (i j) does not also print (B0=0), so error need be modified to:

Error1＝P(i，j)-2α+γ， (2)

In like manner, the pixel of existing processing (i, in the time of j) will prining (B0=1), the ink dot around also can having influence on.As shown in Figure 7, B1=B2=B3=B4=0 does not all print, and the pixel of existing processing (i j) need print (B0=1), so error need be modified to:

Error2＝1-P(i，j)+2α+2β， (3)

Therefore according to pixel (i, j), (i, j-1), (i-1, j-1), (i-1, j) and (error amount of corresponding correction then as shown in Figure 3 for i-1, situation j+1).As shown in the above description, the present invention is according to the characteristic of printer ink dot, and the error amount of each pixel of accurate Calculation is so can accurately print out with the gray-scale distribution of image.Can keep away the problem of known halftoning ink that monochrome technology produces waste, and obtain to print accurately GTG value and back coupling error, the quality of prining increased.

The foregoing description is only given an example for convenience of description, and the interest field that the present invention advocated should be as the criterion so that claim is described certainly, but not only limits to the foregoing description.

Claims (4)

1. one kind has the monochromatic printer system that handles of halftoning, and the image that this printer system is printd is made up of the pixel of a two-dimensional array, wherein, (i j) is listed as the capable pixel of j for this image i, and this printer system comprises:

One updating device, its first input end in order to receive this printer system transmit the pixel desiring to print (i, j), its second input is in order to receive an error signal of feedbacking, revise pixel (i, j+1), (i+1, j-1), (i+1, j), (i+1, value j+1);

One critical value device is coupled to this updating device, when this pixel (i, value j) surpasses a predetermined critical value and then produces a signal of prining this pixel, (i, value j) surpasses this predetermined critical value when this pixel.Then produce a signal of not prining this pixel;

One error determination device, and the signal that is produced according to this critical value device, pixel (i, the information of value j) and the pixel value of before having printd is to produce the error signal of this back coupling; And

One filter, its input are coupled to the error signal that this error determination device is produced, and its output is connected to second input of this updating device.

2. the system as claimed in claim 1 is characterized in that, this error determination device is that (i, j) information of the value and the previous pixel value of prining produces the error signal of this back coupling with lookup table mode for the signal that produced according to this critical value device, pixel.

3. one kind in the print method of halftoning monochrome of printer system, and the image that this printer system is printd is made up of the pixel of a two-dimensional array, and wherein, (i j) is listed as the capable pixel of j for this image i, and this method comprises the following steps:

One input step transmits the pixel desiring to print (i, value j), and receive an error signal of feedbacking in order to receive this printer system, revise pixel (i, j+1), (i+1, j-1), (i+1, j), (i+1, j+1) value repeats above process, up to finishing whole image processing;

One deciding step, when this pixel (i, j) value surpasses a predetermined critical value and then produces a signal of prining this pixel, when this pixel (i, j) value surpasses this critical value of being scheduled to and then produces a signal of not prining this pixel;

One error produces step, according to signal that this deciding step produced, pixel (i, j) information of the value and the previous pixel value of prining is to produce the error signal of this back coupling;

One filter step produces the error signal that step produces with error and carries out filtering, to produce the error signal of back coupling required in the input step.

4. method as claimed in claim 3 is characterized in that, this error produces step, and (i, j) value reaches the information of the pixel value of before having printd, and produces the error signal of this back coupling with lookup table mode according to signal, this pixel that this deciding step produced.

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