KR100440944B1 - Binary image resolution reducing method and device simplifying resolution reduction algorithm - Google Patents

Abstract

PURPOSE: A binary image resolution reducing method and device is provided to perform error diffusion to a next group simply without the help of complicated hardware or software, thereby reducing a screen without deterioration of screen quality. CONSTITUTION: An input binary image data is inputted in a memory(31). The input binary image data is grouped according to a proportion designated by a group generator(32). Pixels grouped in the group generator(32) are forwarded to an output decider(33) to be determined as one of black gray-scale and white gray-scale. An output of the output decider(33) is stored in the memory(31) or forwarded to a printer engine(35) for printing. An error occurring upon deciding the output is stored in an error storage(34) and then forwarded to the group generator(32), such that the error is added to a next group to be decided in the output decider(35).

Description

Method and apparatus for reducing the resolution of binary images

According to the present invention, a predetermined number of pixels is grouped into one group, the gray level of a pixel occupying a plurality of gray levels among the pixels is determined as the color of the group, and the number of errors is processed to the next group. The present invention relates to a method for reducing the resolution of a binary image without reducing image quality and to an apparatus for implementing the same.

In general, when the printing speed of the printer is to be doubled or when the size of the actual screen is to be reduced, there is a need to reduce the resolution than the original image.

As a method of reducing such a resolution in the related art, as shown in FIG. 1, an input image (600 × 600 DPI) 10 represented by two gray scale pixels is simply removed by outputting one pixel per two pixels through a converter. The resolution is reduced by causing the image (300 x 300 DPI) 11 to be output.

As such, the method of reducing the resolution by removing pixels according to the reduction ratio may have advantages in terms of hardware implementation due to a simple algorithm. However, in the case of halftone images, the characteristics of the image tend to be ignored. This becomes large, and as a result, the image quality deteriorates. In order to solve this problem, a method of converting a pseudo (PSEUDO) continuous gradation image was adopted.

2 is a block diagram of another embodiment for reducing conventional resolution.

The input image 21 of two grayscale 600 × 600 DPI is averaged to be converted into a 256 grayscale 600 × 600 DPI pseudo continuous grayscale image 22, and then two pixels of the pseudo grayscale 22 By taking one of these, 256 scaled down images 23 of 300 x 300 DPI are obtained. The output image 24 can be obtained by converting it into a two-gradation image of 300 x 300 DPI.

Such a method can improve image quality by preserving the characteristics of an image by processing a half-tone pixel rather than simply removing one of the binarized pixels of the method shown in FIG. 1, but it is composed of a complex algorithm as described above. There are significant problems in hardware implementation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an apparatus and method for simplifying an algorithm for reducing a resolution and not degrading image quality.

1 is a block diagram for explaining an embodiment of a conventional resolution reduction method;

2 is a block diagram of another embodiment for reducing conventional resolutions,

3 is a block diagram for illustrating the configuration of the present invention;

4 is a flowchart for displaying image reduction steps of the present invention;

5A is an exemplary view showing a grouping state having a reduction ratio of 50% of the width and height of the group;

5B is an exemplary view showing a reduction ratio in the case of having a reduction ratio of 33% in width and 50% in height.

5C is a block diagram illustrating a grouping state in a case where a reduction ratio of 50% in width and 33% in height is shown;

6 is a block diagram for explaining detailed steps determined in an output determination step;

7 is a block diagram illustrating an embodiment of an output determination process of groups of the present invention.

<Description of the symbols on the main parts of the drawings>

31: memory 32: group generator

33: output decision section 34: error storage section

A feature of the present invention for achieving the above object is a memory for storing input binary image data and output binary image data, a group generator for receiving input binary image data stored in the memory and grouping according to a specified ratio; An output determination unit that determines the pixels grouped by the group generation unit as one of two gradations, and an error storage that stores an error generated in the process of determining the output in the output determination unit, and transmits the error to the group generation unit. It is characterized by consisting of wealth.

The present invention also provides a grouping step of receiving data of a binary image and grouping a predetermined number of pixels into one group according to a specified ratio, and determining the grouped group as one of two gray levels in the grouping step. And the output is determined by adding the error generated in the output determination step to a next group to be determined in the output determination step.

Hereinafter, according to the accompanying drawings, it will be described in detail the above features of the present invention in detail.

3 is a block diagram for illustrating the configuration of the present invention.

As shown in FIG. 3, input binary image data is input to the memory 31, and the input binary image data stored in the memory 31 is grouped according to a ratio specified by the group generator 32. The pixels grouped by the group generating section 32 are sent to the output determining section 33 and determined as one of the gray scales of the two gray scales of black and white. The output of the output determination unit 33 is stored in the memory 31 or sent to the printer engine 35 to perform printing, the error generated during the output determination is stored in the error storage unit 15, the error storage unit 15 ) Is sent to the group generator 32 to add the error to the next group to be determined by the output determiner 35 to determine the output.

4 is a flowchart for displaying image reduction steps of the present invention.

Binary image input data is stored in the memory 31 (S31), and the stored binary image input data is formed in units of n pixels (S32), and the output of this group is determined (S33). The generated error is calculated, the error is transmitted to the next group (S33), it is determined whether or not this process is performed for all groups (35), and the process is terminated. In the forming of the grouping (S32), as shown in FIGS. 5A, 5B, and 5C, various methods may exist.

FIG. 5A illustrates a grouping state having a reduction ratio of 50% of the width and length, and FIG. 5B illustrates a reduction ratio of the reduction ratio of 33% of width and 50% of height, and FIG. It is a block diagram showing the grouping state in the case of having a reduction ratio of% and 33%.

6 is a block diagram for explaining the detailed steps of the output determination step.

First, the number of black and white pixels in the group is examined (S61), and it is determined whether the number of black and white pixels is the same (S62). If the number of black and white pixels is the same, the previous group determines the black value (S63). The output of the group is output in black, the error is determined to be a white pixel (S65). In step S63, the output of the current group is made white if not black, and the error is determined to be a black pixel (S66). If the black pixel number is not the same as the white pixel in step S62, it is determined whether the black pixel number is greater than the white pixel number (S64). If it is determined by the number of white pixels existing in the group (S67), and if the number of black pixels is smaller than the number of white pixels in step S64, the process of determining the output of the current group as white and determining the error as the number of black pixels in the current group (S68) Going through.

However, if the group currently being processed in step S63 is the first group of one line, the output is determined to be white and the black pixel number is designated as an error. And, in case of the first group of one line, no error is received.

7 is a block diagram illustrating an embodiment of an output determination process of groups of the present invention.

As shown in FIG. 7A, the embodiment has a reduction ratio of 50% of width and height of grouping two sets of data into four pixel units. In addition, the input data is composed of three white pixels, a first group having one black pixel, and a second group consisting of two white pixels and two black pixels. At this time, the output determination of the first group is determined as a white pixel because the number of white pixels is larger than the number of black pixels, and at this time, the error is determined as black pixels in the state where the number of black pixels is one in the state before the output is determined. Is determined. The error black pixel number 1 is added to the second group, which is the next group, and deformed from two black pixels to three in the original state, thereby maintaining the state as shown in FIG. 7B.

Further, in the output determination of the second group, the state of Fig. 7B is determined to be black because the number of black pixels is three and the number of white pixels is one, and the error is determined to be the number of white pixels 1 and added to the next group. The result at this time is as shown in Fig. 7c.

By determining such an output process in a continuous group, it is possible to obtain a reduced image by determining one representative pixel for each group of four pixels.

According to the above configuration of the present invention, by carrying forward the error to the next group by a simple method without complicated hardware or software support (so-called 'error diffusion' method), there is an effect that can reduce the image quality without damage. .

Claims (4)

A method of reducing the resolution of a binary image, comprising: A grouping step of receiving data of the binary image and grouping a predetermined number of pixels into one group; An output determination step of judging the grouped group as one of two gray levels in the grouping step; and And determining the output of the next group by adding the error generated in the output determination step to the next group to be determined in the output determination step. The method of claim 1, wherein the output determination step A pixel number comparing step of comparing the number of pixels of the two gray levels in the group; And a pixel determining step of determining the number of pixels in the gray level of the group in the pixel number comparing step. The method of claim 2, wherein the output determination step An error judging step of judging the number of decimal pixels as an error number in the pixel number comparing step; And an error adding step of adding the error number to the next group to be determined in the output determination step. A memory for storing input binary image data; A group generator for receiving input binary image data stored in the memory and grouping the input binary image data according to a specified ratio; An output determination unit which determines the pixels grouped by the group generation unit as one of two gray levels; And And an error storage unit for storing an error generated in the process of determining the output by the output determination unit and transferring the error to the group generator.

Images