JPS61154272A - Picture reloading method - Google Patents

Abstract

PURPOSE:To reduce a number of transmission data by counting the number of black or white picture elements in every block which is set up in a binarization picture and reloading a half tone picture by the counting value. CONSTITUTION:After an original picture is binarized by a dither method and the binary picture is divided into 4X4 for example, the number of black picture elements is counted. A density matrix pattern corresponding to the counting value is used for a reconfiguration of a picture. Figure (c) shows the density matrix pattern displayed on every block based upon the number of black picture elements. A decision of the density matrix pattern is made by comparing the same dither matrix DM2 as in a binarization with a density level of every block. Thus, a reloading operation of the picture is finished after the density level of every block is decided by the number of black picture elements and the first density matrix pattern is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image restoration method for restoring a halftone image from a binarized image.

(Prior art) To restore a halftone image using binary image data,
Conventionally, images are reconstructed using the binarized data of each pixel as is.

(Problems to be Solved by the Invention) When binarized image data is stored in memory and read out as needed to reconstruct an image,
There are no particular problems with the conventional restoration method. However, if it is desired to perform processing such as filtering at the time of restoration, the above conventional method cannot handle this at all. Furthermore, when the restoration operation includes the process of transmitting image data to a distant place, the conventional method described above has a problem in that the amount of transmitted data increases.

The present invention has been made in view of these problems, and its purpose is to provide an image restoration method that can reduce the amount of data to be transmitted.

(Means for Solving the Problems) The present invention to solve the above problems counts at least one of the number of black pixels or the number of white pixels for each block set in a binarized image, and based on the counted value. This method is characterized by restoring a halftone image.

(Operation) In the method of the present invention, first, a binarized image is divided into blocks,
The number of black pixels or the number of white pixels in each divided or already divided block is counted. Next, a halftone image is restored using a pattern corresponding to this count value. When it is necessary to transmit image data, the count value is used as the transmission data.

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

1 to 4 are explanatory diagrams of one embodiment of the present invention.

First, a binarized image is the object of image processing, and this binarized image can be easily obtained by using, for example, a 4×4 or 8×8 dither matrix as a threshold value. For example, the setting width of the threshold value constituting this dither matrix is set as wide as 0.1 to 1.4 in reflection density for a gradation surface, and 0.1 in antitAIII1 degree for a line drawing.
It is preferable to narrow the threshold to about 0.5 (or use a fixed threshold).

This is to prevent the image from becoming blank or thick. Further, different types of dither matrices may be used for the gradation plane and the line drawing. In addition, the binarization method is a method other than the dither method,
For example, a density pattern method or a shading method may be used.

In the method of the present invention illustrated in FIG. 1, first, if the image is not a binarized image, the above-mentioned binarization is performed (step 2). Figure 2 shows a distributed type (B
ayer type) dither matrix DM1 (see Figure 2 (a)), the original image A
(see Figure 2 (B)) is binarized, and the 2 values shown in Figure 2 (C) are
An example of obtaining a valued image B is shown. In this figure, the numbers in Ditherer 1 to Rix DMI and in the original image A indicate standardized density levels, and the pixels in the shaded area of the binarized image B are black pixels.

Next, in step (2), the binarized image is divided into blocks of appropriate size. In FIG. 2 (c), the image is divided into 4×4 sizes. Then, the number of black pixels (or the number of white pixels) in each block is counted (step 2).

Figure 3 shows the counting results. As image data, this count value is stored in a memory and read out as needed to reconstruct an image. Here, the block size is equal to the size (4 x 4 or 8 x 8) of the dither matrix (threshold group) used to obtain the binarized image, and preferably smaller than the size of the dither matrix. . In this way, high resolution can be maintained while increasing the number of gradations.

In order to reconstruct an image from the count value (number of black pixels) obtained in this way, a density matrix pattern corresponding to the count value is used. FIG. 4(c) shows a density matrix pattern copied onto each block based on the number of black pixels in each block. This is done by comparing DM2 (see FIG. 4(A)) with the density level (count value, ie, number of black pixels) of each block. For example, in the case of block BK1, its 11 degree level is 7, so the dither matrix D in FIG.
The part of M2 with a density level of 7 or less becomes a black pixel,
A density matrix pattern like the block BK1 in FIG. 4(c) is obtained. This is the reconstructed image. In this embodiment, since the de-Iza matrices DM1 and DM2 are selected to be the same, the restored image, ie, FIG. 4(C), is naturally the same as FIG. 2(C).

In this way, the density level of each block is determined from the number of black pixels and the first density matrix pattern is obtained.
This completes the image restoration operation itself. In addition, Fig. 5 (B) shows the number of converted black pixels in each block as the normalized average density level of each block, and Fig. 5 (C) shows the number of converted black pixels in each block based on the normalized average density level of each block. , a first density matrix pattern is copied onto each block, and the first density pattern in this example is determined using a dither matrix DM2 (see FIG. 5(a)), which is the same as the dither matrix DM1 described above. This is done by comparing the density level of each block.

For example, in the case of block BK1, its density level is 9, so the portion of the dither matrix DM2 in FIG. 5(A) with a density level of 9 or less becomes a black pixel, and the block in FIG. 5(C) This results in a density matrix pattern (restored image) like BK1.

Hereinafter, enlargement/reduction of restored images that are possible using the present invention will be listed for reference.

In order to enlarge or reduce the restored image obtained by the present invention, for example, after obtaining the first density matrix pattern, a second density matrix pattern of a size corresponding to the enlargement/reduction magnification is obtained for each block. Then, arrange these in block order to obtain an enlarged/reduced image. Figure 6 (a) is an enlarged image obtained in this way with an enlargement factor of 5/4.
b) is a reduced image with a reduction magnification of 3/4. Here, the first
゜The size ratio of the second density matrix pattern is according to the vertical and horizontal expansion/reduction magnification, and the vertical and horizontal size of the second density matrix pattern is the vertical and horizontal size of the first density matrix pattern.・It is multiplied by the reduction magnification. Therefore, in the example of Fig. 6, Fig. 6 (
In the case of (a), the size is 5 x 5, and in Fig. 6 (b), the size is 3 x 3.

In this example, the mother pattern obtained by two-dimensionally arranging the corresponding patterns in the first density matrix pattern is to be found when divided by the size of the second m-degree matrix pattern. A pattern having the same positional relationship as the second density matrix pattern is cut out and used as the corresponding second density matrix pattern. FIG. 7 is an explanatory diagram (enlargement magnification: 5/4) showing an example of obtaining a second density matrix pattern from a first density matrix pattern.
l, f12+f13. ..., f21+f22+...
, . . . as blocks F+ (size: 5×5) of the second density matrix pattern Ft 2
, Ft 3+..., 'F21. F22...
It shows the state divided into... First, block ``!
As the second density 71 to density pattern corresponding to f11.1, all blocks f11. f12°f13. ...+f2
1+f22+, . . . use a pattern cut out at the position of block F11 from a mother pattern that is assumed to contain the same first density matrix pattern corresponding to block fil. Similarly, the second density matrix pattern corresponding to block F12 includes all blocks f+t, ft2 . f+3. −, f
21, f22. . . . use a pattern cut out at the position of block F12 from a mother pattern that is assumed to contain the same first density matrix pattern corresponding to block f12. That is, the second density matrix pattern corresponding to block Fij includes all blocks f11, f12 . f131...
+f21+f22+...

A pattern located at the position of block Fij is cut out from a mother pattern that is assumed to contain the same first density matrix pattern corresponding to block Fij. The above-mentioned FIG. 6(a) shows the second density matrix pattern obtained in this way arranged on a plane. The same applies to FIG. 6(b).

Note that it is not necessary that the dither matrices DM1 and 0M2 are made of the same material; for example, the matrix DM2 may be of a dot concentration type (spiral type).

Further, a specific method for obtaining the pattern of each block after scaling described above is to actually configure the aforementioned mother pattern in memory,
Data at a predetermined address may be read out to obtain a pattern, but this would require an extremely large memory capacity. Therefore, instead of actually creating a mother pattern, attention may be paid to the periodicity of the pattern, and the density of each pixel may be determined in the following manner to obtain a pattern after scaling.

That is, in the case of expansion (magnification m/n), x in the first block in the row direction of the new block (block after expansion)
The pattern in the row is AD1=mod [x-+-mo in the first block in the row direction of the block before expansion.
d [(1-1) (m-n).

n]+1-2. The pattern in the yth column in the 0th block in the column direction of the new block that is equal to the pattern in the 0th row in the column direction of the new block is ΔD2=mod [y +mod [(J-1)
(m-n).

n]+1-2. n ]+equal to the pattern in the 1st column, while reduced (a8 rate m/mouth)
In the case of , the x-th row pattern in the first block in the row direction of the new block (the block after reduction) is in the first block in the row direction before reduction. mod [x+mod
[(I-1) (n-In-ml>,
n ]+1 −2. The pattern in the yth column in the Jlth block in the column direction of the new block, which is equal to the pattern in the 0th row in the column direction of the block before reduction, is AD2=mod [y +mod [ (J-1)
(n −I n−ml), n ]+1−2. n
] - Equivalent to the pattern in column 1111.

Here, mod [1], q] is the remainder of p-2 to q, and is naturally smaller than q.

Therefore, if the pixel temperature of each block before scaling is stored in memory, it can be easily updated by reading out the pixel temperature in the corresponding block before scaling by using ADl and △D2 as addresses in the row and one column direction. You can get a pattern of blocks.

(Effects of the Invention) As explained above, the present invention includes the operation of dividing a binarized image into blocks and counting the number of black pixels (or the number of white pixels) for each block. It is possible to reduce the

[Brief explanation of the drawing]

FIG. 1 is a J-flow diagram showing an example of the method of the present invention, FIG. 2 is an explanatory diagram showing an example of binarization in FIG. 1, and FIG.
The figure shows the count values of black pixels, FIG. 4 is an explanatory diagram of the restored image, FIG. 5 is an explanatory diagram of the first density 71 to density pattern, and FIG. 6 is the second density matrix pattern. expansion·
FIG. 7 is an explanatory diagram of a reduced image (gi), and is an explanatory diagram of a method for obtaining a second density 7-trix pattern from a first density matrix pattern. DMl, DM2...Dither matrix △...Original image B...Binarized image f11. f12.・・・
・, f21. f22. ...Block F111F+21..., F of the first density matrix pattern
21 * r 22 ,...Second density matrix pattern block Patent applicant Roku Konishi Photo Industry Co., Ltd. Agent Patent attorney Fuji Ijima 1 person

Claims (1)

[Claims] An image restoration method characterized by counting at least one of the number of black pixels or the number of white pixels for each block set in a binarized image, and restoring a halftone image from the counted value.