JPH0918714A - Image processing method and its device - Google Patents

Abstract

PURPOSE: To make the resolution compatible with the gradation by changing the size of a threshold level matrix depending on a change in the gradation between pixels of an original image. CONSTITUTION: An arithmetic circuit 12 calculates the difference of the gradations between pixels adjacent to each other based on original image gradation data, divides the pixel group into plural groups when the sum of the absolute values of each difference reaches 850 or over, calculates the sum of the absolute values of the difference for each group, and as to the group where the calculated sum reaches 850 or over, the circuit 12 divides sequentially the pixel group belonging to the group till the sum of the absolute values of the difference in the group is less than 850. Then a small threshold level matrix is set for a group in which a change in the density of the original image is steep among threshold level matrices stored in a ROM 18 to generate a binary image with high resolution and a large threshold level matrix is set for a group in which a change in the density of the original image is slow among threshold level matrices stored in the ROM 18 to generate a binary image with high gradation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus, and more particularly to an image suitable for generating binarized information for printing an image from multi-tone image information obtained from an original image. The present invention relates to a processing method and device.

[0002]

2. Description of the Related Art When printing a halftone image with a binary printer such as a laser beam printer, a multi-tone image information obtained from an original image is binarized by a dither method or an error diffusion method. Is performed, and the binarized information is converted into a pseudo intermediate image. Here, the binarization process is a process of replacing the shading of an image with the coarseness / fineness of pixels. In addition, the dither method uses N × input images.
Compared with the threshold matrix of N, binarize for each pixel, address the rows and columns of the threshold matrix according to the movement of the pixel of the input image information, read each threshold value in sequence, and read the read threshold value. This is a processing method of comparing the size with the gradation number of pixels and sequentially binarizing each pixel of the input image information from the comparison result.

Conventionally, as a threshold value matrix used for the binarization processing, as described in JP-A-60-180370, a matrix in which the size of the matrix and the array of threshold values are fixed, or JP-A-Sho-sho. It is known that the size of the matrix changes, as described in JP-A-60-145767.

[0004]

The former one of the prior arts uses a fixed threshold matrix when performing the binarization processing by the dither method. Therefore, when the matrix is enlarged, it is binarized. The gradation of the pseudo-halftone image is smooth, but the resolution is coarse. On the contrary, when the matrix is made small, the resolution becomes fine but the smoothness of gradation is lost. On the other hand, the latter is
When changing the size of the matrix, the target image is a combination of two types of image patterns, a halftone image and a line drawing, so the pixel of interest and this pixel are used as a criterion for determining the size of the matrix to be used. The difference value of the gradation of only the pixels adjacent to each other is used. For this reason, it is difficult to perform gradation processing of a halftone image showing various kinds of density changes with different gradients.

An object of the present invention is to change the size of the threshold matrix according to the gradation change between pixels of the original image, thereby making it possible to achieve both resolution and gradation, an image processing apparatus, and an image processing apparatus. To provide a printer device.

[0006]

In order to achieve the above-mentioned object, the present invention relates to a pixel group which forms a specified surface based on multi-tone image information obtained from an original image of the pixel group, and is adjacent to each other. The difference in the number of gradations between the pixels is calculated, and when the total value of the differences is equal to or more than the set value, the pixel group forming the specified surface is divided into a plurality of groups, and each group is adjacent to each other. The total value of the differences in the number of gradations between the pixels is calculated according to the multi-tone image information, and the total value of the differences in the number of gradations in the group is less than the set value for a group whose calculated value exceeds the set value. Pixel groups belonging to the group are sequentially divided into a plurality of groups until one becomes, and any one of a plurality of threshold matrices having different thresholds for size and binarization is set for each group according to the number of pixels. Then
This is an image processing method for generating binarized information corresponding to pixels belonging to each group according to each threshold matrix. When adopting this image processing method, when a pixel group belonging to a group is sequentially divided into a plurality of groups, the group is adjusted until the total value of the differences in the number of gradations in the group is less than or equal to a set value or the number of pixels in the group becomes 1. It is also possible to sequentially divide the pixel group belonging to the above into a plurality of groups.

Further, according to the present invention, based on the multi-gradation image information obtained from the original image of the pixel groups arranged in a grid pattern, the gradation between adjacent pixels in the pixel group for the nth power of 2 is calculated. The difference between the numbers is calculated, and when the total value of the differences is equal to or greater than the set value, the n-th row pixel group is divided into a plurality of groups,
The total value of the differences in the number of gradations between adjacent pixels for each group is calculated according to the multi-gradation image information, and the total difference in the number of gradations in the groups for which the calculated value exceeds the set value is calculated. Pixel groups belonging to the group are sequentially divided into a plurality of groups until the value becomes less than the set value, and one of a plurality of threshold matrices having different thresholds for size and binarization is set according to the number of pixels. The image processing method is adopted for each group, and binarized information corresponding to the pixels belonging to each group is generated according to each threshold matrix.

In adopting this image processing method, when the pixel group is sequentially divided into a plurality of groups, the total value of the differences in the number of gradations in the group is equal to or less than the set value or the number of pixels in the group becomes one. It is also possible to sequentially divide the pixel group belonging to the group into a plurality of groups.

Further, the present invention provides, as a device, a difference in gradation number between adjacent pixels for a pixel group forming a specified surface based on multi-tone image information obtained from an original image of the pixel group. A difference calculating means for calculating, a main total value calculating means for calculating a sum of absolute values of the differences from the calculated values of the difference calculating means,
Main dividing means for dividing the pixel group forming the specified surface into a plurality of groups when the calculated value of the main total value calculating means becomes equal to or more than a set value, and a phase for each group divided by the main dividing means. Regarding the auxiliary total value calculation means for calculating the total value of the absolute values of the differences in the number of gradations between adjacent pixels according to the multi-tone image information, and the group in which the calculated value of the auxiliary total value calculation means exceeds the set value. The auxiliary dividing means for sequentially dividing the pixel group belonging to the group into a plurality of groups until the total value of the absolute values of the differences in the number of gradations in the group becomes less than the set value, and the size and the threshold value for binarization are different from each other. A threshold matrix storage means for storing a plurality of threshold matrices, and a threshold matrix storage means stored in the threshold matrix storage means for each group divided by the main dividing means and the auxiliary dividing means. A threshold value matrix setting unit that sets one of the threshold value matrices according to the number of pixels, and binarization that generates binarization information corresponding to the pixels belonging to each group according to each threshold value matrix set by the threshold value matrix setting unit. The image processing apparatus includes an information generating unit.

Further, according to the present invention, based on the multi-gradation image information obtained from the original image of the pixel groups arranged in a grid pattern, n of 2 is obtained.
Difference calculating means for calculating the difference in the number of gradations between adjacent pixels in the pixel group for the running, and main total value calculating means for calculating the sum of absolute values of the differences from the calculated values of the difference calculating means. And a main dividing unit that divides the pixel group corresponding to the n-th row of 2 into a plurality of groups when the calculated value of the main total value calculating unit is equal to or more than a set value, and each group divided by the main dividing unit. The auxiliary total value calculating means for calculating the total value of the absolute values of the differences in the number of gradations between the pixels adjacent to each other according to the multi-tone image information, and the calculated value of the auxiliary total value calculating means exceed the set value. For each group, auxiliary dividing means for sequentially dividing the pixel group belonging to the group into a plurality of groups until the total value of the absolute values of the differences in the number of gradations in the group becomes less than the set value, and a threshold for size and binarization. Multiple threshold matrices with different And a threshold matrix storage unit that stores the threshold matrix, and for each group divided by the main dividing unit and the auxiliary dividing unit, one of the threshold matrices stored in the threshold matrix storing unit is set according to the number of pixels. Threshold matrix setting means,
2 corresponding to the pixels belonging to each group according to each threshold matrix set by the threshold matrix setting means
The image processing apparatus includes a binarized information generating unit that generates binarized information.

In constructing each of the image processing apparatuses, as the auxiliary dividing means, the sum of the absolute values of the differences in the number of gradations in the group for which the calculated value of the auxiliary total value calculating means exceeds the set value is The pixel group belonging to the group may be sequentially divided into a plurality of groups until the number of pixels is equal to or less than the set value or the number of pixels in the group becomes one.

According to the present invention, any one of the above image processing devices and a printing means for printing an image of dots on a printing paper according to the binarized information generated by the binarized information generating means of any one of the image processing devices. There is a configuration of a printer device provided with.

[0013]

According to the above-mentioned means, when performing binarization of a halftone image, a plurality of threshold matrices having different sizes and different thresholds for binarization are prepared, and the phase difference among the pixels in the range to be binarized is set. A threshold matrix to be used is selected according to the distribution of the difference in gradation number between adjacent pixels, and binarization information is generated according to each pixel according to the selected threshold matrix to achieve both resolution and gradation. I have decided. That is, with respect to the pixel group forming the specified surface or the pixel group of the n-th power line sentence of 2 based on the multi-gradation image information obtained from the original image of the pixel group, the difference in the number of gradations between adjacent pixels is calculated. Calculate,
When the total value of the differences is equal to or greater than the set value, the pixel group forming the specified surface or the pixel group of the n-th power line sentence of 2 is divided into a plurality of groups, and the number of gradations between adjacent pixels is set for each group. The sum of the differences is calculated according to the multi-tone image information.
For groups where this calculated value is less than the set value,
A threshold matrix is set according to the number of pixels belonging to the group, and for groups whose calculated value is greater than or equal to the set value, the difference in the number of gray levels in the group is calculated until the total value is less than the set value or the number of pixels in the group becomes 1. The pixel group belonging to the group is sequentially divided into a plurality of groups. Then, a threshold matrix corresponding to the number of pixels belonging to each group is set for each group, and binarization information corresponding to the pixels belonging to each group is generated according to each threshold matrix. In this case, in the halftone image, since the difference in the number of gradations between pixels is small and the total value of the difference in the number of gradations is small for an image with a smooth gradation change, Is set to a large threshold matrix. On the other hand, in the case of an image that requires resolution such as fine characters and thin lines, the number of gradations of the printing part such as characters and lines is large compared to the surrounding non-printing part, so the difference value between pixels Also tends to be large, a small threshold matrix is set for this group. Therefore, a small threshold matrix is set for a portion where the image density changes sharply, binarized information with high resolution is generated, and a large threshold matrix is set for a portion where the image density is gentle. As a result, binarized information with high gradation is generated.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an image processing apparatus showing an embodiment of the present invention. In FIG. 1, the image processing apparatus includes a pixel gradation number memory 10, an arithmetic circuit 12, a difference information memory 14, a dither pattern memory 16, a ROM 18, and a binarized image data memory 20. The pixel gradation number memory 10 is adapted to store original image gradation number data as multi-gradation image information obtained from an original image of pixel groups arranged in a grid pattern, and ROM 18
Stores a plurality of threshold matrices having different sizes and different thresholds for binarization. The arithmetic circuit 12 fetches the original image gradation number data from the pixel gradation number memory 10, and based on this data, a pixel group or n of 2 constituting the designated surface.
With respect to the pixel group of the line-up sentence, a difference calculation means for calculating a difference in gradation number between adjacent pixels and storing the calculated value in the difference information memory 14 is configured. Further, the arithmetic circuit 12 constitutes a main total value calculating means for calculating the total value of the absolute values of the respective differences stored in the difference information memory 14, and the calculated value of the main total value calculating means is a set value, for example 850. When it becomes the above, the main dividing means for dividing the pixel group forming the designated surface or the pixel group of the n-th power line sentence of 2 into a plurality of groups is configured. Further, the arithmetic circuit 12 has auxiliary total value calculating means for calculating the total value of the absolute values of the differences between the gradations of the adjacent pixels in each group divided by the main dividing means in accordance with the original image gradation number data. In a group in which the calculated value of the auxiliary total value calculation means is a set value, for example, 850 or more, the total absolute value of the differences in the number of gradations in the group is less than the set value, or the number of pixels belonging to the group is 1. Until then, an auxiliary dividing means for sequentially dividing the pixel group belonging to the group into a plurality of groups is configured. In addition, the arithmetic circuit 1
2 is R as a threshold matrix storing means for each group divided by the main dividing means and the auxiliary dividing means.
A threshold matrix stored in the OM 18 is set, threshold value matrix setting means for storing the set threshold matrix in the dither pattern memory 16 is configured, and pixels belonging to each group according to each threshold matrix stored in the dither pattern memory 16 are configured. Binarized image information is generated as the corresponding binarized information, and the binarized information generation means for storing the binarized image data in the binarized image data memory 20 is configured.

Next, the operation of the image processing apparatus shown in FIG. 1 will be described with reference to the flowchart of FIG.

First, as an original image of a pixel group arranged in a grid pattern, as shown in FIG. 3, for example, the image size in the main scanning direction is 2480 pixels and the image size in the sub scanning direction is 3496 pixels. When inputting the multi-gradation image information obtained from the original image, the original image gradation number data regarding the pixels (2480 × 8) of 8 rows (2 3 rows) of the original image is input (step S1). ). After that, as shown in FIG. 4, the input pixel group is divided into 310 blocks, and the pixel groups of each block are sequentially processed as a pixel group forming a surface or a pixel group for the cube row of 2. For each pixel,
As shown in FIG. 5, the original image gradation number data from 0 to 255 is set as the gradation number.

Therefore, the arithmetic circuit 12 sequentially takes in the original image gradation number data for 8 × 8 pixels from the pixel gradation number memory 10 and calculates the difference in gradation number between adjacent pixels of 8 × 8 pixels. The calculated value is stored in the difference information memory 14 (step S2). In this case, when the number of gradations of the pixel P1 is 1, the number of gradations of the pixel P2 is 155, and the number of gradations of the pixel P9 is 8, as shown in FIG. And the difference value between the pixel P2 and 139 is
147 is calculated as the difference value between the pixel P1 and the pixel P9. This difference value is calculated for all pixels, and it is determined whether the total value S of the absolute values of the difference values is a set value, for example, 850 or more (step S4). At this time, when the total value S is 850 or more, the pixel groups belonging to the group shown in FIG.
Divide into 4 parts. After this, return to step S3 again,
Based on the difference value stored in the difference information memory 14, the total value S of the absolute values of the differences in each of the groups g1 to g4 is calculated.
Then, it is determined whether the total value S in each of the groups g1 to g4 is 850 or more (step S4). At this time, since the total value S of the group g3 is less than 850, this group g3 is left as it is. On the other hand, the total value of the groups g1, g2, and g4 is 21 each.
Since the calculated values are 78, 1903, and 1568, the groups g1, g2, and g4 are again divided into four, as shown in FIG. That is, the group g1 is divided into groups g5, g6, g7, and g8, the group g2 is divided into groups g9, g10, g11, and g12, and the group g4 is divided into groups g13, g14, g15, and g16 (step S5). And each group g5-g
The total value S of the absolute values of the differences for each of 16 groups
Is calculated again. At this time, since the total value S of the other groups except the group g9 is less than 850, the pixels in the group are again divided into four only for the group g9. This process is repeated until the total value S of the absolute values of the differences in the group is less than 850 or the number of pixels in the group becomes 1. When the group g4 is divided into four groups g17 to g20 and all the total values in each group are less than 850, the first input 8 ×
The 8 pixel groups are divided into groups as shown in FIG.

When the processes of steps S1 to S5 are repeated and division of all blocks is completed (step S6), a threshold matrix is set for each group (step S7). In this case, FIG. 10 (a)
As shown in (d) to (d), among the threshold matrixes M1 to M4 stored in the ROM 18, a threshold matrix according to the number of pixels belonging to each group is set for each group. That is, the threshold matrix M1 is configured as a threshold matrix corresponding to 8 × 8 pixels, and the threshold matrix M2 is configured as a threshold matrix corresponding to 4 × 4 pixels. Also, the threshold matrix M
3 is configured as a threshold matrix corresponding to 2 × 2 pixels, and the threshold matrix M4 is configured as a threshold matrix corresponding to 1 × 1 pixels. Thresholds corresponding to the respective pixels are set in the respective threshold matrices M1 to M4. Therefore, when the 8 × 8 pixel group is divided into groups as shown in FIG. 9, the group g3
Is set to a threshold matrix M2, and groups g5 to
A threshold matrix M3 is set for g8 and g10-g16, and a threshold matrix M is set for groups g17-g27.
4 is set. After that, binarized image data is generated as binarized information corresponding to each pixel according to the threshold matrices M1 to M4 for each group (step S8).
In this case, the number of gradations of each pixel is the threshold matrix M1 to M.
Data of 1 or 0 is generated depending on whether or not the threshold value set to 4 is exceeded. In the case of performing such dither processing, when the binary value, that is, one pixel of the original image is made to correspond to one dot at the time of printing, the dither pattern memory 16 is composed of a memory element of 8 × 8 bits. When the dithering process is multi-valued, that is, when one pixel of the original image is made to correspond to a plurality of dots at the time of printing, the dither pattern memory 16 requires a storage capacity of N × 8 bits (N ≧ 16).

Next, when the image processing apparatus of this embodiment is applied to a printer, for example, when multi-tone image information as shown in FIG. 11 is obtained from the original image, this multi-tone image is obtained. As a threshold matrix for information,
A threshold matrix as shown in 2 is set. When pixels are binarized and printed according to the threshold matrices M1 to M4, an image as shown in FIG. 13 is displayed as dots.

As described above, according to this embodiment, by using the small threshold matrices M3 and M4 for the portion of the original image where the density changes sharply, it is possible to generate a binarized image with high resolution. By using the large threshold value matrixes M1 and M2 for an image in which the density of the original image changes gently, a binarized image with high gradation can be generated, and gradation change between pixels of the original image can be prevented. Accordingly, both resolution and gradation can be compatible.

In the present embodiment, when setting the threshold matrices M1 to M4, the dither pattern memory 16 has a value obtained by multiplying the width of the original image by the number of rows of the threshold matrices M1 to M4. Since the method of sequentially processing while storing in the memory is adopted, the memory capacity of the dither pattern memory 16 can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the present embodiment, a difference information memory 22 is provided in place of the difference information memory 14 and a dither pattern memory 24 is provided in place of the dither pattern memory 16, and the other configuration is as shown in FIG. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the difference information memory 22 and the dither pattern memory 24 correspond to the same number of pixels as the original image gradation number data, that is, 2480 × 8 pixels, like the pixel gradation number memory 10. It is made up of capacity. Therefore, in the present embodiment, the difference information memory 22
With respect to the dither pattern memory 24, the arithmetic processing corresponding to the original image gradation number data initially stored in the pixel gradation number memory 10 can be performed at one time, and the binarization processing can be performed more than the above-described embodiment. It can be done at high speed.

Next, a third embodiment of the present invention will be described with reference to FIG.

In this embodiment, the arithmetic circuit 12 is composed of a CPU 26, and a difference information memory 14 and a dither pattern memory 1 are provided.
6. The binarized image data memory 20 is replaced with the image processing memory 28.
CPU 26, image processing memory 28, ROM 1
8 are connected to each other via the system bus 30.

In this embodiment, steps S1 to S1 shown in FIG.
Since the CPU 26 processes the processing of step S8 and stores the processing result in the image processing memory 28, the circuit configuration can be simplified as compared with the above-described embodiments.

[0029]

As described above, according to the present invention,
When binarizing a halftone image, a threshold matrix is set according to the distribution of difference values of the original image density, and a small threshold matrix is set for image information with a sharp change in the original image density. However, since a large threshold value matrix was set for image information with a gradual change in density of the original image, it is possible to generate a binarized image with a high resolution according to a matrix with a small threshold value, and a gradation according to a matrix with a large threshold value. It is possible to generate a highly binarized image, and it is possible to achieve both resolution and gradation according to the gradation change between pixels of the original image.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the device shown in FIG.

FIG. 3 is an explanatory diagram of a configuration of an original image.

FIG. 4 is a diagram showing a method of dividing multi-tone image data.

FIG. 5 is a diagram showing a relationship between pixels and the number of gradations.

FIG. 6 is a diagram showing a gradation number difference between pixels.

FIG. 7 is a diagram for explaining a method of dividing a pixel group.

FIG. 8 is a diagram for explaining a method of dividing a pixel group.

FIG. 9 is a diagram for explaining a threshold matrix setting method.

FIG. 10 is a diagram showing a configuration example of a threshold matrix.

FIG. 11 is a configuration diagram of original image data.

FIG. 12 is a diagram showing an example of setting a threshold matrix for original image data.

13 is a diagram showing a display example of a binarized image generated according to the threshold matrix shown in FIG.

FIG. 14 is a block diagram showing a second embodiment of the present invention.

FIG. 15 is a block diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 10 pixel gradation number memory 12 arithmetic circuit 14 difference information memory 16 dither pattern memory 18 ROM 20 binarized image data memory

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Shibuya 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref.

Claims (9)

[Claims] 1. A difference in gradation number between adjacent pixels is calculated for a pixel group forming a specified surface based on multi-gradation image information obtained from an original image of the pixel group, and each difference is calculated. When the total value is equal to or more than the set value, the pixel group forming the specified surface is divided into a plurality of groups, and the total value of the differences in the number of gradations between the adjacent pixels in each group is the multi-level. The pixel group belonging to the group is sequentially divided into a plurality of groups until the total value of the differences in the number of gradations in the group becomes less than the set value for the group whose calculated value exceeds the set value. , One of a plurality of threshold matrices having different sizes and different thresholds for binarization is set for each group according to the number of pixels,
An image processing method for generating binarized information corresponding to pixels belonging to each group according to each threshold matrix. 2. A difference in gradation number between adjacent pixels is calculated for a pixel group forming a specified surface based on multi-gradation image information obtained from an original image of the pixel group, and each difference is calculated. When the total value is equal to or more than the set value, the pixel group forming the specified surface is divided into a plurality of groups, and the total value of the differences in the number of gradations between the adjacent pixels in each group is the multi-level. Pixel groups belonging to a group calculated according to the tonal image information, and until the total value of the differences in the number of gradations in a group for which the calculated value exceeds the set value is less than the set value or the number of pixels in the group becomes 1. Are sequentially divided into a plurality of groups, and any one of a plurality of threshold matrices having different sizes and binarization thresholds is set for each group according to the number of pixels, and each group is set according to each threshold matrix. Belongs to Image processing method for generating binarized information corresponding to a pixel. 3. A difference in the number of gray levels between adjacent pixels for a pixel group of 2 n rows based on multi-tone image information obtained from an original image of the pixel groups arranged in a grid pattern. When the total value of the differences is equal to or more than the set value, the pixel group corresponding to the n-th row of 2 is divided into a plurality of groups, and the number of gradations between adjacent pixels is calculated for each group. A pixel group belonging to a group is calculated until a total value of differences is calculated according to the multi-tone image information, and a total value of differences in the number of gradations in the group for which the calculated value exceeds the set value is less than the set value. Are sequentially divided into a plurality of groups, and any one of a plurality of threshold matrices having different sizes and binarization thresholds is set for each group according to the number of pixels, and each group is set according to each threshold matrix. Corresponding to the pixels belonging to An image processing method for generating binarized information. 4. A difference in the number of gradations between adjacent pixels for a pixel group of 2 n rows based on multi-gradation image information obtained from an original image of pixel groups arranged in a grid pattern. When the total value of the differences is equal to or more than the set value, the pixel group corresponding to the n-th row of 2 is divided into a plurality of groups, and the number of gradations between adjacent pixels is calculated for each group. A total difference value is calculated according to the multi-tone image information, and for a group whose calculated value exceeds the set value, the total difference value of the number of gray levels in the group is less than the set value or the number of pixels in the group is 1 Pixel groups belonging to the group are sequentially divided into a plurality of groups until one becomes, and any one of a plurality of threshold matrices having different thresholds for size and binarization is set for each group according to the number of pixels. Each threshold according to each threshold matrix. An image processing method for generating binarized information corresponding to pixels belonging to a loop. 5. A difference calculation means for calculating a difference in gradation number between adjacent pixels for a pixel group forming a specified surface based on multi-tone image information obtained from an original image of the pixel group. ,
Main total value calculating means for calculating the sum of absolute values of the respective differences from the calculated values of the difference calculating means, and pixels forming the designated surface when the calculated value of the main total value calculating means becomes equal to or more than a set value. A main dividing unit that divides the group into a plurality of groups, and a sum of absolute values of differences in the number of gradations between adjacent pixels of each group divided by the main dividing unit is calculated according to the multi-tone image information. Pixels belonging to the group until the total value of the absolute values of the differences in the number of gradations in the group for which the calculated value of the auxiliary total value calculation unit exceeds the set value is less than the set value. An auxiliary dividing means for sequentially dividing the group into a plurality of groups, a size and 2
Any one of a threshold matrix storage means for storing a plurality of threshold matrices having different thresholds for thresholding and a threshold matrix stored in the threshold matrix storage means for each group divided by the main dividing means and the auxiliary dividing means. Threshold value matrix setting means for setting the threshold value matrix according to the number of pixels, and binarization information generating means for generating the binarization information corresponding to the pixels belonging to each group according to each threshold value matrix set by the threshold value matrix setting means. An image processing apparatus comprising: 6. A difference calculating means for calculating a difference in gradation number between adjacent pixels for a pixel group forming a specified surface based on multi-tone image information obtained from an original image of the pixel group. ,
Main total value calculating means for calculating the sum of absolute values of the respective differences from the calculated values of the difference calculating means, and pixels forming the designated surface when the calculated value of the main total value calculating means becomes equal to or more than a set value. A main dividing unit that divides the group into a plurality of groups, and a sum of absolute values of differences in the number of gradations between adjacent pixels of each group divided by the main dividing unit is calculated according to the multi-tone image information. And the total value of the absolute values of the differences in the number of gradations in the group for which the calculated value of the auxiliary total value calculation means exceeds the set value is less than the set value or the number of pixels in the group is Auxiliary dividing means for sequentially dividing the pixel group belonging to the group into a plurality of groups until the number becomes 1, a threshold matrix storing means for storing a plurality of threshold matrices having different thresholds for size and binarization, and a main dividing means. And a threshold matrix setting means for setting one of the threshold matrices stored in the threshold matrix storage means for each group divided by the auxiliary dividing means according to the number of pixels, and set by the threshold matrix setting means An image processing apparatus, comprising: binarized information generating means for generating binarized information corresponding to pixels belonging to each group according to each of the threshold matrices thus generated. 7. A difference in the number of gradations between adjacent pixels for a pixel group corresponding to 2 n rows based on multi-gradation image information obtained from an original image of the pixel groups arranged in a grid pattern. And a main total value calculating means for calculating the sum of absolute values of the respective differences from the calculated values of the difference calculating means, and when the calculated value of the main total value calculating means exceeds a set value. N of 2
A main dividing unit that divides the pixel group for the driving into a plurality of groups, and a sum of absolute values of differences in the number of gradations between adjacent pixels of each group divided by the main dividing unit is the multi-level. The total value of the absolute values of the differences in the number of gradations in the group is less than the set value for the auxiliary total value calculation unit that calculates according to the toned image information and the group for which the calculated value of the auxiliary total value calculation unit exceeds the set value. Auxiliary dividing means for sequentially dividing a pixel group belonging to the group into a plurality of groups, a threshold matrix storing means for storing a plurality of threshold matrices having different sizes and binarization thresholds, a main dividing means and an auxiliary dividing means. A threshold matrix for setting one of the threshold matrices stored in the threshold matrix storage means for each group divided by A box setting unit, an image processing apparatus and a binary information generating means for generating a binary information corresponding to the pixels belonging to each group in accordance with respective threshold matrix set by the threshold matrix setting means. 8. A difference in the number of gradations between adjacent pixels in a pixel group for 2 n rows based on multi-tone image information obtained from an original image of pixel groups arranged in a grid pattern. And a main total value calculating means for calculating the sum of absolute values of the respective differences from the calculated values of the difference calculating means, and when the calculated value of the main total value calculating means exceeds a set value. N of 2
A main dividing unit that divides the pixel group for the driving into a plurality of groups, and a sum of absolute values of differences in the number of gradations between adjacent pixels of each group divided by the main dividing unit is the multi-level. Auxiliary total value calculating means for calculating in accordance with the toned image information, and for a group whose calculated value of the auxiliary total value calculating means exceeds the set value, the total absolute value of the differences in the number of gradations in the group is less than the set value or the group. An auxiliary dividing unit that sequentially divides a pixel group belonging to a group into a plurality of groups until the number of pixels in the group becomes 1, and a threshold matrix storing unit that stores a plurality of threshold matrices having different sizes and different thresholds for binarization. , One of the threshold matrices stored in the threshold matrix storage means for each group divided by the main dividing means and the auxiliary dividing means An image including threshold value matrix setting means for setting corresponding to each group and binarization information generating means for generating binarization information corresponding to pixels belonging to each group according to each threshold value matrix set by the threshold value matrix setting means. Processing equipment. 9. The image processing apparatus according to claim 5, 6, 7 or 8, and the image by dots according to the binarized information generated by the binarized information generation means of any one of the image processing apparatuses on a printing paper. A printer device comprising a printing means for printing.