JPH0476677A - Method and device for thinning-out reduction of image data - Google Patents

Abstract

PURPOSE:To prevent an image from blurring and to perform a high-speed thinning-out process by dividing original image data into matrixes in a plane and varying the relative position of one picture elements extracted from each matrix by mXn adjacent matrixes. CONSTITUTION:Sampling start points of (m) horizontal lines whose start points are in the same matrix on image data should be positioned in (m) laterally adjacent matrixes including the matrix, one by one. Further, only one start point of one horizontal line among the (m) horizontal lines is present in the matrix positioned at the start points of the horizontal lines. Then the start points of the horizontal lines should be at different position in (n) longitudinally adjacent matrixes. The sampling start position of each horizontal line is determined satisfying said three conditions and picture elements are sampled at a period (mXn); and then a picture element of one dot is selected from each matrix on the original image data and picture elements which are sampled at the period (mXn) are present on optional vertical and horizontal lines.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is applicable to personal computers, electronic filing devices, and other types of image data input.

Preservation 2 Regarding the improvement of an image processing device equipped with functions for processing such as display, printing, and conversion, it is particularly important to improve the image processing device, which is capable of performing processing such as display, printing, and conversion.
This image solves the problem of low processing speed, which is a drawback of the OR thinning method, and achieves both the advantages of both by reducing image distortion and performing high-speed thinning processing. The present invention relates to a data thinning reduction method and apparatus.

BACKGROUND OF THE INVENTION Image processing devices such as personal computers and electronic filing devices have been equipped with image editing functions that allow them to input, save, display, print, and convert image data. Is going.

By the way, image data conversion processing methods in conventional image processing apparatuses, particularly thinning/reducing methods, are roughly divided into two methods: a simple thinning processing method and an OR thinning processing method.

First, in the first simple thinning method, when creating a reduced image, sampling processing of reduced pixels from the original image data is performed at sampling intervals corresponding to the reduction ratio in both the vertical and horizontal directions. ing.

As a result, according to this simple thinning method, one dot in the vertical and horizontal directions disappears after thinning if its horizontal line or vertical line is buzzed from the sampling period.

The simple thinning method has the advantage that it can be executed in a short time because the reduction process is simple, but on the other hand, as mentioned above, the reduction process thins out buzzing dots from the sampling period, so it is When the image data is characters, line drawings, etc., there is a problem in that "black" dots forming fine parts are missing.

On the other hand, in the second OR thinning method, pixels are sampled from the original image data in the same way as the simple thinning method, but even one pixel within the sampling interval on the top, bottom, left, and right of the original image data that includes the sampled pixel is sampled. If a "black" dot is included, the sampled pixel is processed as a "black" dot.

Therefore, according to this Orr thinning method, fine parts such as characters and line drawings will not be lost.

However, on the other hand, if there is a fine pattern on the original image data, 1 to 2 after OR thinning become blank black, and the entire pattern is painted black.

Therefore, the image data after the OR thinning process becomes blackish overall (so-called image collapse).
There is a drawback.

Furthermore, since it is necessary to judge whether each pixel is black or white and determine whether the pixel is black or white after one thinning, the processing speed is significantly lower than that of the simple thinning method.

As described above, each of the two conventional thinning methods, the first simple thinning method and the second OR thinning method, has advantages and disadvantages.

Furthermore, the image data to be subjected to the thinning/reducing process can be roughly divided into two types: half-tone images such as pictures and photographs, and images such as characters.

-For boat fishing, mid-tone image data such as paintings and photographs are
The first simple thinning method, which causes less image distortion, is appropriate, and considering the fact that image data containing fine text is often composed of one-dot lines, the second method is used. The OR thinning method is more suitable.

However, for image data that contains text and photographs/pictures, etc., only one of the thinning methods can be adopted (the thinning method determined at the time of system design). Image data quality is 1
Become a victim of thinning processing.

Incidentally, in addition to such image editing processing, cases in which thinning/reducing processing is required include display operations in electronic filing devices and the like.

In other words, in an image processing device such as an electronic filing device, when inputting, saving, printing, etc.
Compared to the accuracy of the image resolution (number of dots) possessed by the processing system, the display resolution of a display device such as a CRT or LCD is lower (the number of dots is smaller).

Therefore, in order to display the high-resolution image data read by the processing system on a display screen such as a CRT, it is necessary to thin out the image data to match the resolution of the display.

Generally, the OR thinning method has a problem of low processing speed, so the simple thinning method is often adopted.

To summarize the above, the two conventional image reduction processes, namely the first simple thinning method, have a fast processing speed, but the ``black'' bits that form fine parts are missing. The quality of image data containing fine text deteriorates, and
The second OR thinning method does not cause the loss of "black" dots, but the problem is that halftone image data such as pictures and photographs become dark overall and the processing speed decreases. For image data that contains a single character and a photo/picture, etc., in an image processing device such as an electronic filing device, only one of the thinning methods can be used. The quality of the image data deteriorates.

Therefore, in the conventional simple thinning method and or thinning method, it is important to prevent image distortion and to avoid ^'G8! This has the disadvantage that it is incompatible with the I-degree thinning process.

Problems that Akira attempts to solve In this invention, we will solve these problems in the conventional image data thinning/reduction method, and in particular, in the case of the conventional simple thinning method, the image data may be reduced due to the loss of 11-bits or 1 line. An image data thinning/reducing method that solves the problem of the image being destroyed and the problem of low processing speed, which is a drawback of the OR thinning method, and achieves both prevention of the destruction of five images and high-speed thinning processing. and equipment.

Plate 1 on the other hand) [0-mu-me] 1 move" λ In this invention,
First, in the image processing stage j3, which is equipped with functions such as manual processing, storage, display, printing, and conversion of image data, the pixels constituting the image data in bitmap format are non-blending. and then reduce it to another bitmap format image data.

When the image reduction ratio is 1/m in the vertical direction and 1/n in the horizontal direction of one image data (where m and n are positive integers), the original image data is m dots vertically and n dots horizontally) - The plane is divided into matrices, and the relative position of one pixel selected from each 71 to 6 pixels is changed in adjacent m×n matrices.

Second, in the image data thinning/reduction method described in -1-, each of the plane-divided 71 to 62 pixels.

Select one pixel from each matrix and thin out the image data so that the selected pixels are distributed with a period of m x n. Try to create and be.

Thirdly, in the image data thinning/reduction method also mentioned at the beginning.

Horizontal 1j: I+1 consisting of mxrl dots adjacent on the opposite side
The horizontal sample starting points in the 71-ricks are set to be different from each other.

Fourth, in an image processing system that has functions for inputting, storing, displaying, printing, and converting image data, pixels constituting image data in a bitmap format are sampled to create an image in the same bitmap format. When reducing to data.

The reduction ratio of the image is 1/rn in the vertical direction of the image data,
When the horizontal direction is 1/n, means to divide the original image data into a matrix of m dots vertically and n dots horizontally, and select one pixel from each matrix and perform thinning reduction processing to create image data. means, the pixels to be selected are m× on arbitrary vertical lines and horizontal lines on the original image data.
A means for performing selection processing so as to be distributed with a period of n.

Next, embodiments of the image data thinning/reducing method of the present invention will be described in detail with reference to the drawings.

This embodiment corresponds to the invention described in claims 1 to 3.

First, the principle of the image data thinning/reducing method of the present invention will be explained.

In the thinning/reducing method of the present invention, when thinning and reducing image data, the reduction ratio is set to 1/m in the vertical direction and 1/m in the horizontal direction.
/n (where m and n are positive integers), as in the conventional simple thinning method, the image data is divided into planes by a matrix of n×m (dots), and from each matrix,
Extract one pixel and create reduced image data.

In this case, in the conventional simple thinning method, the relative position of the pixel extracted within the matrix (element of the matrix)
In contrast, in the image data thinning/reduction method of the present invention, the position of the extracted pixel is determined based on the horizontal and vertical lines of one dot at any position on the screen having the same length. The difference is that pixels are sampled with the same number of pixels.

In other words, the first feature of the image data thinning/reducing method of the present invention is that the relative positions of pixels extracted within the matrix are changed so that the pixels are sampled at the same linear density. There is.

FIG. 2 is a diagram illustrating plane division in the image data thinning/reduction method of the present invention. In the drawing, S.D.
is the original image data, M is the number of dots in the vertical direction, N is the number of dots in the horizontal direction, Lv is a vertical line of length M dots on the original image data SD, and Ll is also the length N on the original image data SD. A horizontal line of dots is shown, and . is a selected pixel.

In FIG. 2, the reduction ratio of one image is 1/m in the vertical direction and l/n (m) in the horizontal direction of the original image data SD.

n is a positive integer), and the case where the original image data SD is reduced is shown.

Here, an arbitrary vertical line on the original image data SD.

The conditions for sampling horizontal lines at the same l11A density will be explained.

First, the number of selected pixels included between the vertical line Lv and the horizontal line is determined.

First, the total number of pixels of the original image data SD is MXN (dots), and the number of pixels after reduction processing is obtained by multiplying this MXN (dots) by the vertical and horizontal reduction ratios.

In this example, the reduction values are vertical and #A is m, respectively.
Since n, the number of pixels after reduction is as shown in the following equation.

That is, becomes.

In order to make the number of pixels of the horizontal line LH equal after the reduction process, no matter where the horizontal line LH is located on the original image data SD, the selected number of pixels existing on the horizontal line LH must be set. The value of (number of pixels after thinning processing) may be made equal to the value obtained by dividing the total number of pixels after reduction by the total number M of horizontal lines.

That is, the number of pixels selected above the horizontal line may be any number.

This point also applies to the vertical direction, and the vertical line Lv
No matter where it exists on the original image data SD,
In order to make the number of pixels of the vertical lines Lv equal after the reduction process, the number of pixels selected on each vertical line Lv should be as follows.

Furthermore, in order to process the reduced vertical lines and horizontal lines so that they both have a uniform dot distribution, pixels may be selected periodically on each straight line.

Therefore, the period of each vertical line and horizontal line is.

It is calculated by dividing the number of dots on each straight line by the number of pixels selected.

That is, the selection period of pixels on the horizontal line LH is similarly
The selection period of pixels on the vertical line Lv is as follows.

From equations (4) and (5), it can be seen that the periods of the vertical line and the horizontal line are both (m x n ), and that they are equal.

Next, the pixels selected at this period (m x n) are always 1 in the m x n (dot) matrix on the original image data SD.
We will explain the processing method for the existence of one.

FIG. 1 is a diagram for explaining the principle of reduction processing in the image data thinning/reduction method of the present invention. □11SI21...JSlm is the sample start point of each horizontal line on each line from line 1 to line m, 5111Szl+...+S
nl indicates the starting point of each horizontal line of n matrices adjacent in the vertical (longitudinal) direction.

In FIG. 1, each rectangular area represents an m×n (dot) matrix obtained by dividing original image data.

In relation to the above-mentioned Figure 2, in the horizontal direction (horizontal line) of the original image data SD, the number of pixels in the horizontal direction, N (dots), is divided by (nXm), which is N/nXm (dots). )
The matrices of are arranged consecutively in the right direction.

Similarly, in the vertical direction (vertical line LV), the number of pixels, M (dots), is divided by (m x n), which is M/m x n.
(number of) matrices are arranged consecutively in the downward direction.

Here, a method of selecting pixels on each horizontal line while moving the horizontal line from the top to the bottom of the image data will be described.

There must be one selected pixel in each matrix into which image data is divided.

Therefore, for the horizontal direction, the sample starting point S,
, , S, □, ......, S must exist in each of m horizontally adjacent matrices including the matrix.

In addition, in the vertical direction, for n consecutive matrices in the vertical direction from point A at the upper left corner on the image data, each matrix always has one horizontal line starting point 5ilvS21y...・・S□ (However, R
==1~m) must exist.

As is clear from this FIG. 1, the starting point S11? of each horizontal line? It can be seen that Szl+..., S□ have different values from 1 to n.

As described above, in the image data thinning/reduction method of the present invention, in the horizontal direction, each sample starting point S, 1°S□2.・・・・・・
..., Syu, exists in each matrix, and in the vertical direction, there are n adjacent to each other in the vertical direction.
Sample starting point S of horizontal line of matrix
+sl*+...+Snl is reduced so that one each exists in each matrix.

When the above-described positional relationship of one selected element is applied to the entire image data, the following three conditions need to be satisfied.

(2) The sample starting points of m horizontal lines whose starting positions are in the same matrix on the image data must be located one in each of the m horizontally adjacent matrices that include that matrix.

■ The matrix located at the starting point of the horizontal line has 1
The starting point of - horizontal lines among m horizontal lines is 1
Only one exists.

■ The starting point of the horizontal line in ■ above is at a different position (phase) in each of the n vertically adjacent matrices.
must be.

To summarize these conditions, for each horizontal line, if the sampling start position is determined so that the three conditions (■ to ■) above are satisfied, and pixels are sampled at a period (m x n), the original image Dot pixels are selected from each matrix on the data, and pixels sampled at a period (m×n) can exist for any vertical line or horizontal line.

The second feature of the image data thinning/reducing method of the present invention is that the thinning/reducing process is performed based on the above-mentioned basic recognition (the invention set forth in claim 2).

A concrete example of a mathematical formula for realizing the reduction method of the present invention described above is as follows.

If the sample start position is 84 on the horizontal line, then S4=
n (D-1) +k - (6) However,
k = 1~n, Q = 1-m Also, for each line number, if Q is i, then k'' ((i-1) /m
) mod n +1...(7) Q = (i-1)lIlod m +1...
It can be obtained by (8).

Here, the operator mod is rXmodYJ, then
Indicates the value of the remainder when divided by Y.

Furthermore, in equation (7), the decimal places of [(i-1)/m:l are rounded down.

As a specific example based on the above equations (6) to (8), the case where m-2°n=2 is shown as follows.

Line 1: i=1. ni=1. m=1. S,=1 line 2: i=2. ni=1. m=2. S,,=3 line 3: i=3. ni = 2. ! ! =1,53=2 line 4
: i=4. ni = 2. m=2,54=4 line 5:
j = 5. ni=i, Q=1. S,=1 (hereinafter, ni,Q,
(S) is the same repetition) Next, an example of the state of the sample starting point in each line "2" obtained by these equations (6) to (8) will be described.

FIGS. 3 (1) and (2) are diagrams showing an example of an image thinned out by the image data thinning/reduction method of the present invention,
(1) shows the original image data, and (2) shows the image after thinning and reduction. In Figure IJ, SDl is the source image, ■D is the image after thinning and reduction, C~I] is a row or column of both source images, and A'~1]' is a row or column after thinning. ,・marks indicate selected pixels.

This embodiment is a case where the horizontal sample starting points in 111 71-ricks made up of horizontally adjacent niXn dots are made different (invention described in claim 3). .

The original image data is 12×8 (dots), m=2, n=
2, so the matrix is 2X2 (dots)
becomes.

As shown in FIG. 3 (1), the original image data is ], 2
It is image data of X8 (dot), and 2 surrounded by a thick line
It is composed of a matrix of X2 (dots).

The squares in each matrix represent pixels, and selected pixels are marked with a *.

Then, as shown in FIG. 3(1), the source image Sl
), in the 7 tricks of 2×2 (dots),
There is always one pixel marked, and any horizontal line or vertical line from 11 to 10 has a circumference of 1tJI 41'(').

Image I1 after thinning and reduction shown in FIG. 3(2). ),teeth,
In the source image 5()1 of FIG. 3(1), the image is formed by the pixels marked with ".".

That is, the soap in Figure 3 (1), 1) lj iq, 2(
F)□1. , the line A- of 1 ton 1 with diagonal lines
B and CD are images T D after thinning and reduction in Fig. 3 (2).
In □, the dotted lines are A'-B' and C'-D'.

Therefore, in the conventional simple thinning processing method, A-B
, C-D, after thinning and reduction, one becomes a one-dot straight line and the other is erased, whereas in the image data thinning and reduction method of this invention, both become dotted lines every other dot. I understand what will happen.

In the case of image data reduction processing, it is ideal that a straight line of one dot becomes a straight line of 0.5 dots. However, in reality, such representation of 0.5 dots is impossible.

In the thinning/reducing method of the present invention, the representation of one dot by a dotted line after thinning can be thought of as a straight line with a density of 172, so the reproducibility of straight lines is better than in the conventional simple thinning method. I can understand that it's good.

As described above, a line of one dot in the horizontal and vertical directions can be erased by differentiating the horizontal sample starting points in m matrices of m×n dots that are adjacent in the horizontal direction. is gone,
Furthermore, no distortion of one image occurs.

Inugo* II 2 Next, an embodiment of the image data thinning/reducing device of the present invention will be described in detail. This embodiment corresponds to the invention set forth in claim 4.

FIG. 4 is a functional block diagram showing a detailed embodiment of the main structure of the image data thinning/reducing device of the present invention. In the drawings, 1 is a keyboard, 2 is a main control unit, 3 is a spacer, 4 is a scanner control unit, 5 is a display, 6 is a display control unit, 7 is an external storage device, 8 is an external storage control unit, and 9 is a printer, 10 is a printer control unit, 11 is a main memory, 12 is an image memory,
13 is a display memory, 14 is an image processing section, 15 is an encoding/decoding section, and 16 is a system bus.

The thinning/reducing device r of the present invention shown in FIG. Select and perform the reduction process. The operation of this image processing section 14 will be explained in detail later.

The functions of each part of the thinning/thinning/reducing apparatus of the present invention shown in FIG. 4 are as follows.

A keyboard 1 is an input means for inputting instructions from an operator, and inputting image data.

Storage 9 Instructions regarding processing such as display, printing, and conversion are input.

The main control unit 2 is a central processing unit that has the function of managing and controlling the entire system.

The scanner 3 is an image input means that is controlled by the scanner control section 4 and reads one image data.

The display 5 is a CRT or LC that is controlled by the display control unit 6 and visually displays one image data on the screen.
This is a display means such as D.

The external storage device 7 is a large-capacity storage device such as a hard disk that is controlled by the external storage control section 8.

The printer 9 is controlled by a printer control unit 1o,
It is a printing means that prints image data.

The main memory 11 is a memory means for storing programs for controlling the system shown in FIG. 4 and as a work area.

The image memory 12 is a memory that stores image data input from the scanner 3.

The display memory 13 is a memory that stores data displayed on the display 5.

The image processing unit 14 has a function of thinning out image data and the like.

The encoding/decoding unit 15 encodes image data,
It has the function of decoding encoded data.

These units are connected via a system bus 16 and exchange data with each other.

Next, the operation of the image data thinning/reducing process of the thinning/reducing apparatus of the invention of El- shown in FIG. 4 will be described.

When the keyboard 1 instructs the hexagonal direction of the image scanner, the main control section 2 instructs the scanner control section 4 to input image data using a program stored in the main memory 11 .

Upon receiving this command, the scanner control unit 4 scans the image with the scanner 3 and stores the obtained image data in the image memory 12.

Next, if the resolution of the display 5 is lower than the resolution of the input image stored in the image memory 12, the main control section 2 instructs the image processing section 14 to thin out and reduce the image data.

Upon receiving this command, the image processing section 14 thins out and reduces the image data stored in the image memory 12 using the above-mentioned reduction method to create reduced image data.
3.

Thereafter, the display control unit 6 displays the reduced image data on the display memory 13 on the screen of the display 5.

Through the above operations, the image data input by the scanner 3 is thinned out and reduced in size and displayed on the screen of the display 5.

Note that when storing this image data in the external storage device 7, the image data on the image memory 12 is encoded by the encoding/decoding section 15, and is stored in the external storage device 7 via the external storage control section 8. Remember.

In addition, when printing one image data, one image memory 12
The above image data is output to the printer 9 under the control of the printer control section 10, and a printing operation is performed.

As already mentioned, the image data thinning/reducing apparatus of the present invention is characterized by the operation of the image processing section 14 shown in FIG.

Here, the image thinning/reducing process performed by the image processing unit 14 will be described in detail.

Figures 5 (1) and (2) are diagrams showing a specific example of one image data for thinning processing by the thinning/reducing device of the present invention, (1) is the original image data, and (2) is the thinning/reducing data. Shows an image of In the drawing, SD2 is the source image,
ID2 is the image after thinning and reduction, a and b are the dot numbers, i
and j are line numbers, and m and n are vertical and horizontal reduction values.

In Figure 5 (1) and (2), the vertical and horizontal reduction values are
m=2. It is assumed that n=2.

The individual dots of the image data ID2 after thinning and reduction shown in FIG. 5(2) are selected one by one from the m×n (dot) matrix of the original image data SD2 of FIG. 5(1).

The selection method in this case is as shown by the above-mentioned equations (6) to (8).

Therefore, if the b-th dot on line j of the reduced image D2 is the pixel selected from the a-th dot on line i of the original image data SD, the relationship between the two can be expressed by the following equation. can.

i= (b-1) god m +1 +mX (j-
1)・・・・・・(9) a= 34 + m×n (b-1) 7m・・・・
-(10) Note that in equation (10), the decimal part of (b-1) 7m is rounded down. Further, S4 is a value calculated using the above equation (6).

The image processing unit 14 performs arithmetic processing according to the above equations (6) to (10), and stores the original image data in the memory (for example, the first
A process is performed in which pixels are selected bit by bit from the image memory 12 in FIG. 1 and transferred to a reduced image memory (for example, the display memory 13 in FIG. 1).

Here, the thinning/reducing process performed by the image processing unit 14 will be explained with reference to a flowchart.

FIG. 6 is a flowchart showing the process flow at the time of image reduction in the image processing section 14 of the thinning/reducing apparatus of the present invention shown in FIG. In the drawings, #1 to #10
indicates a step.

In step #1, the number of lines of the reduced image, 41 J'', is calculated from the vertical reduction value m.

In step #2, the number of dots in the horizontal direction "B"' of the reduced image is calculated from the value n of one reduction in the horizontal direction.

In the next step #3, the line number of the reduced image is set to ``j=1''.
”.

In step #4, the dot number of the reduced image is set to "b=1".

In step #5, the line number riJ and dot number "a" of the original image are calculated from equations (6) to (10) above.

In step #6, line number "i" of the original image.

The bit of dot number "a" is transferred to the reduced image memory.

In step #7, rb=b+IJ is set, and in the next step #8, it is determined whether b>B.

If b>B, the process returns to step #5 and the same process is performed.

When it is detected in step #8 that b>B, the process proceeds to step #9 and sets rj=,j+1.

In step #10, it is determined whether j>J.

If j>J is not satisfied, the process returns to step #4 and the same process is performed thereafter.

If it is detected in step #10 that j>J, the flow shown in FIG. 6 is ended.

Through the above steps #1 to #10, the image data reduction process by the image data thinning/reduction apparatus of the present invention is completed.

Note that in one or more embodiments, the case where the original image data is reduced and displayed on the display screen has been mainly described.

However, it goes without saying that the present invention is not limited to display operations, and can be similarly implemented in normal image editing.

Therefore, it is clear that the image data thinning/reducing method and apparatus of the present invention are not limited to display operations, but also include reduction processing of original image data during image editing.

According to the image data thinning/reducing method and apparatus of the present invention, one dot line in the horizontal and vertical directions is not erased unlike the conventional simple thinning method. Unlike the OR thinning process, image distortion does not occur.

In addition, since the thinning/reducing method can be realized through relatively simple processing, many excellent effects such as the first one can be achieved with little reduction in processing speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the principle of reduction processing in the image data thinning/reducing method of the present invention, FIG. 2 is a diagram for explaining plane division in the image data thinning/reducing method of the present invention, and FIG. FIGS. (1) and (2) are diagrams showing examples of images that have been thinned out by the image data thinning/reduction method of the present invention. FIG. 4 is a functional block diagram showing a detailed embodiment of the essential configuration of the image data thinning/reducing device of the present invention, and FIG. 5 (1) and (2) show the thinning/reducing device of the present invention. FIG. 6 is a flowchart showing the flow of processing when reducing one image in the image processing unit 14 of the thinning/reducing apparatus of the present invention shown in FIG. 1. . In the drawing, 1 is a keyboard, 2 is a main control unit, and 3 is a keyboard.
is a scanner, 4 is a scanner control unit, 5 is a display,
6 is a display control unit, 7 is an external storage device, 8 is an external storage control unit, 9 is a printer, 10 is a printer control unit, 1
1 is a main memory, 12 is an image memory, 13 is a display memory, 14 is an image processing section, and 15 is an encoding/decoding section. Patent applicant: Rico Shinzu Co., Ltd.

Claims (1)

[Scope of Claims] 1. In an image processing system having functions for inputting, saving, displaying, printing, converting, etc. image data, sampling pixels constituting image data in a bitmap format and dividing the pixels into separate When reducing the image data to bitmap format image data, if the image reduction ratio is 1/m in the vertical direction and 1/n in the horizontal direction (however, m and n are positive integers), then the original Divide the image data into a matrix of m dots vertically and n dots horizontally, and calculate the relative position of one pixel selected from each matrix.
A thinning/reducing method characterized by changing in adjacent m×n matrices. 2. In the image data thinning/reducing method described in claim 1, for each plane-divided matrix, pixels selected on arbitrary vertical lines and horizontal lines on the original image data have a period of m×n. A thinning/reducing method characterized in that one pixel is selected from each of the matrices to create thinned/reduced image data so as to be distributed. 3. In the image data thinning/reducing method as set forth in claim 1, the thinning is characterized in that horizontal sample starting points in m matrices each consisting of horizontally adjacent m×n dots are made different. Reduction method. 4. In an image processing system equipped with functions for inputting, saving, displaying, printing, converting, etc. image data, pixels constituting image data in a bitmap format are sampled and converted into another image in the same bitmap format. When reducing the image data to data, if the image reduction rate is 1/m in the vertical direction and 1/n in the horizontal direction, the original image data is m dots vertically and n dots horizontally.
means for dividing the plane into matrices of dots; means for selecting one pixel from each matrix and performing thinning/reduction processing to create image data; 1. A thinning/reducing device comprising: means for performing selection processing such that the numbers are distributed with a period of m×n.