JPH04286274A - Image processor - Google Patents

Abstract

PURPOSE:To provide variable power without breaking a binarized dither pattern by executing conversion from multi-level data to binary data and thinning or interpolating the binary image data at every dither matrix. CONSTITUTION:Binarized image data is inputted from an image input device 10, stored in an image storage memory 14 through an input device interface 12 and thinned by a specified variable power rate at every dither matrix so as to be transferred to an another area. When the respective binarized dither matrixes such as nine dither matrixes 30 consisting of 8X8 image elements, for example, are simply executed thinning, a black line part is thinned as shown in the dither matrixes 32 so as to break the dither matrixes. Then, information is reduced by thinning by a dither matrix unit as shown in the dither matrixes 34. This way of thinning or an interpolation is executed by changing the size of the dither matrixes.

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 that thins out or interpolates dithered image data.

0002

2. Description of the Related Art Conventionally, binary recording has been widely used to express halftones in image data processing. The method of expressing halftones using this binary recording is as follows:
It is divided into dither method and density pattern method. Here, the dither method refers to a method in which each pixel takes only two values, black and white, but multiple gradations of light and shade are expressed by changing the density of black pixels within a minute area. The density of black pixels is determined by binarizing using a predetermined threshold value that changes for each pixel in a square area (dot matrix) of constant pixels. Among these dithering methods, a systematic dithering method that creates a threshold array that appears disjointed according to a certain rule is generally used.

In the systematic dither method, (n×n)+1 gradations can be expressed by assigning different threshold values to n×n pixels. Although the error in gradation display can be reduced by increasing this n, the area of the display unit increases and the resolution deteriorates. When transferring dithered image data, the normal data is compressed before being transferred. When dithering image data is thinned out, simple thinning is performed using a threshold value near the center.

[Problem to be solved by the invention]

However, when a binary image created by the dither method is thinned out, the dither matrix is destroyed and the quality of the image is degraded. This is because the dither matrix itself pseudo-expresses the gradation of one pixel. Therefore, a first object of the present invention is to provide an image processing device that scales data without destroying the dither matrix. A second object of the present invention is to provide an image processing device that scales data without destroying the dither matrix even if the image input device has different gradations. A third object of the present invention is to provide an image processing device that can freely edit an image by changing the magnification of the dither matrix in the main scanning direction and the sub-scanning direction.

[0005]

[Means for Solving the Problem] The image processing apparatus according to claim 1 includes a conversion means for converting image data from multivalued data to binary data by dither processing, and a binary image converted by the conversion means. The first object is achieved by comprising an image input means for inputting data, a memory for storing the input binary image data, and a means for thinning out or interpolating the binary image data for each dither matrix. . In the image processing apparatus according to the second aspect, the thinning or interpolation means of the image processing apparatus according to the first aspect achieves the second object by changing the size of the dither matrix and performing thinning or interpolation. In the image processing apparatus according to claim 3, the thinning or interpolating means of the image processing apparatus according to claim 1 thins out or interpolates the main scanning direction and the sub-scanning direction of the dither matrix at an arbitrary scaling factor. Achieve objective 3.

[Operation] The image processing device of the present invention reduces/reduces image data converted to binary data in dither matrix units.
By enlarging, without destroying the dither matrix,
Process and transfer data.

【Example】

An embodiment of the image processing apparatus of the present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 is a schematic diagram showing the configuration of an embodiment of an image processing device. Figure 2 shows a specific example of data thinning using conventional simple thinning.
FIG. 4 is a diagram comparing an example in which thinning is performed in units of dither matrices, which is an embodiment of the present invention. Binarized image data is input from the image input device 10 and stored in the image storage memory 14 via the input device interface 12. Then a predetermined magnification factor, for example 1
/2, each dither matrix is thinned out and transferred to another area.

As shown in FIG. 2, when a dither matrix consisting of n×n pixels is binarized and then the data is thinned out, the dither matrix will be destroyed if the data is simply thinned out. The dither matrix can be transferred without destroying it. For example, in the case of an 8×8 dither matrix where n=8, when data is multiplied by 1/2, 8-bit transfer and 8-bit thinning are repeated in the main scanning direction. On the other hand, in the sub-scanning direction, after transferring 8 lines, the next 8 lines are thinned out. By repeating this process, data can be transferred with the magnification changed to 1/2.

[0008] In other words, if the nine dither matrices 30, each of which has been binarized and is made up of 8×8 pixels, are simply thinned out, the black line portions will be thinned out as shown in 32, so the dither matrix will be destroyed. On the other hand, in the case of 34, which is thinned out in units of dither matrices, the data is thinned out without destroying the dither matrix, so the information can be reduced. Therefore, this method allows natural scaling of data.

Next, the flow of operations in this embodiment will be explained with reference to the flowchart of FIG. First, it is determined whether input/output addresses for binarized image data have been set (step 1). If it is set (step 1)
;Y), proceed to the next step, and if it is not set (Step 2
;N), return to the start. Then, it is determined whether the input location is a thinning line (step 2). If it is not a thinning line (step 2; N), a main scanning direction matrix is input (step 3).

[0010] It is determined whether this should be thinned out (step 4), and if it is not something that should be thinned out (step 4; N), it is output to the destination (step 5). Then, the output address is added (step 6). Next, 1
Determine whether the line has ended (step 7). If not completed (step 7; N), step 3
Return to and input the main scanning direction matrix again.

After inputting the main scanning direction matrix, it is again determined whether or not to thin out (step 4), and if the data should be thinned out (step 4; Y), the process proceeds to step 7. When it is determined in step 7 that one line is completed (step 7; Y), it is determined whether the process is completed (step 9). If it is not finished (step 9; N), return to step 2. If it is a thinned out line in step 2 (step 2: Y), the thinned out N line address is added (step 8). Thereafter, the process proceeds to step 9, and if it is necessary to end (step 9: Y), the process ends.

0012

According to the image processing apparatus according to claim 1,
Natural data scaling can be performed without destroying the binarized dither pattern. According to the image processing device according to claim 2,
It also supports image input devices with different gradations, allowing for natural scaling of data. According to the image processing apparatus according to the second aspect, output data can be freely edited by changing the magnification ratio of the data in the main scanning direction and the sub-scanning direction.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of an embodiment of an image processing apparatus of the present invention.

FIG. 2 is a diagram showing a comparison between dither matrix transfer, which is an embodiment of the image processing apparatus of the present invention, and transfer of a conventional example.

FIG. 3 is a flowchart showing the order of operations in an embodiment of the image processing apparatus of the present invention.

[Explanation of symbols] 10...Image input device 12...Input device interface 14...Image storage memory

Claims (3)

[Claims] 1. Conversion means for converting image data from multivalued data to binary data by dither processing, image input means for inputting binary image data converted by the conversion means, and input binary data. An image processing device comprising: a memory for storing image data; and means for thinning out or interpolating the binary image data for each dither matrix. 2. An image processing apparatus in which the thinning or interpolating means changes the size of a dither matrix and performs thinning or interpolation. 3. Claim 1, wherein the thinning or interpolating means thins out or interpolates the main scanning direction and the sub scanning direction of the dither matrix at an arbitrary magnification ratio.
image processing device.