JPH10111666A - Method of image processing and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to display an inexpensive and high quality image by using pixel format with higher density in a high edge part in an image, and being subjected to halftone processing in part of weak edge and dull change in brightness by using high tone pixel format. SOLUTION: An edge detection circuit 16 checks it with each of R, G, and B channels whether or not edge exists in four adjacent pixel data received from a line buffer 13. A pixel format selection circuit 17, if any edge was detected, outputs a pixel format selection signal for selecting a high density format, and if not, outputs a pixel format selection signal for selecting a low density format. A halftone processing circuit 14 receives a same group of pixel data as the edge detection circuit 16 received, and operates a halftone processing on them according to the pixel format selection signal inputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing method using a display device having an array of a plurality of pixels capable of independently controlling luminance, and an image processing method thereof.

[0002]

2. Description of the Related Art Conventionally, in a display device using a binary device having two states of lighting and non-lighting, a pixel division method is known as a method for giving each pixel a plurality of luminance levels. In this method, one logical pixel is constituted by a plurality of physical sub-pixels, and gradation is realized by a combination of lighting of the sub-pixels, and is considered as a kind of area gradation method.

For example, as shown in FIG. 1, if one pixel is divided into two sub-pixels having an area ratio of 1: 2,
It is possible to express four gradations of 1, 2, and 3. In the multi-gradation realization method by pixel division, if the number of divisions is increased, the number of gradations can be increased accordingly. However, in general, the area ratio is a power-of-two series (1, 2, 4,
8, 16,...), The number of gradations with respect to the number of divisions can be obtained most efficiently. For example, when one pixel is formed from the same four sub-pixels, as shown in FIG. 2, if the pixel is equally divided into four, only five gradations can be obtained, but 1: 2:
When divided into 4: 8, 16 gradations can be obtained.

According to the configuration shown in FIG. 2, 16 gray levels from level 0 to level 15 can be obtained. As described above, a display using a binary device can obtain multiple gradations by pixel division.
The number of gradations cannot always be taken sufficiently large. In particular, in the case of division by a power-of-two sequence, the larger the number of divisions, the smaller the minimum sub-pixel. Usually, it is difficult to accurately manufacture a fine cell area and control its switching, which leads to an increase in cost.

If the number of divisions is increased, the scale of the drive circuit is correspondingly increased, which also leads to an increase in cost. In addition, as a matter of course, a finer packaging technology is required. As described above, since there is a practical limitation on the number of gradations obtained by pixel division, pseudo halftone processing is used to obtain further gradation expression. As the pseudo halftone processing, an error diffusion (ED) method and a dither method generally used in printers, copiers and the like can be applied. However, when obtaining a certain number of gradations by pixel division and expressing more gradations by pseudo halftone processing, one problem may occur. That is, the shift of the center of gravity of the density of the sub-pixel in the gradation change by the pixel division.

For example, as described above, when a pixel of each color of one pixel is divided into four sub-pixels, FIG.
When the sub-pixel is simply configured as described above, the position of the lit sub-pixel greatly moves between certain adjacent gradation levels due to the pseudo halftone processing. For example, in FIG.
When the pixel having the configuration of the level 7 is changed to the level 8 by the pseudo halftone processing, the density barycenter is set to the gradation level 7
From the center of gravity to the center of gravity of the gradation level 8. This shift of the density centroid may cause a new concentration of energy, and the pseudo halftone processing may have an adverse effect.

[0007] The term "between adjacent levels" means an adjacent level between the gradation level n and the gradation level n + 1 in FIG. Of the combinations between adjacent levels, the shift of the center of gravity is particularly large between the gradation levels 7 and 8. As a result, when pseudo halftone processing is used, a coarse texture may be generated in an image including a natural gradation change such as a photograph or a video captured image.

As described above, this phenomenon occurs, for example, when an image includes a portion where pixels at gradation levels 7 and 8 by pixel division are adjacent to each other, by pseudo halftone processing, for example. It is conceivable that the change of the pixel of the gradation level 7 to the gradation level 8 or the change of the pixel of the gradation level 8 to the gradation level 7 causes the movement of the center of gravity with a large density.

Therefore, there is a demand for a sub-pixel division method that hardly causes such a bad phenomenon. As a pixel division method in which the density barycenter shift is small, each pixel is divided into four (16 gradations)
In the case of, the one shown in FIG. 4 is known. According to this division method, as shown in FIG. 5, the movement of the center of gravity between the gradation level 7 and the gradation level 8 does not change in the horizontal direction but becomes a pair of small movements in opposite directions in the vertical direction. Conceivable.

As a result, even in an image having a gradual gradation change between these levels, the generation of the coarse texture described above is greatly suppressed. As described above, the above-described problem can be overcome by arranging the sub-pixels more finely. However, in general, in the case of a so-called simple matrix drive in which each line is sequentially scanned, if the number of lines increases, the number of lines increases. As a result, the frequency required for rewriting the display of one screen (refresh frequency) decreases.

As a result, there arises another problem that a screen flickers or a moving image is not displayed smoothly. However, the refresh cycle can be maintained by simultaneously selecting and displaying the sub-pixels arranged in the upper and lower targets among the sub-pixels having three lines in the horizontal direction.

Further, if the division can be made one step further, the movement of the center of gravity can be further suppressed by further dividing the horizontal direction as shown in FIG. Until now, the case of expressing the gradation of a single color has been described. In the case of the color, for example, pixel division is performed for each of R / B / G colors, and these are arranged side by side. Many colors can be displayed, including intermediate colors.

As described above, if pixel division is used, a certain number of gradations can be obtained even in a display using a binary device. However, depending on the type and use of an image, it is critical for the image quality. The factor may not be the resolution in the luminance direction such as the number of gradations, but the spatial resolution as measured by DPI (dots / inch).

For example, there are a case where a high-definition monochrome scanned image such as 400 DPI is displayed, and a case where a delicate font is also required to be previewed in DTP. Alternatively, when a display is used as a medium replacing paper in the future, high-definition display is expected to improve the visibility of characters and thin lines and to reduce fatigue when reading. However, the method of using small sub-pixels obtained by pixel division only for the number of gradations cannot exhibit the spatial resolution inherent in the display.

The inventor has devised a technique of changing the size of a pixel by changing the combination of sub-pixels constituting one pixel to realize a plurality of resolutions on one display. FIG. 7 shows an example of such division. In this case, the area surrounded by the solid line is a total of 18 areas including the 6 red areas, the 6 green areas, and the 6 blue areas.
A region is provided, and a pixel having 16 levels for each color can be obtained by a combination of turning on / off of each region. It should be noted that although 64 levels can be represented by 6 areas for each color, the upper area and the lower area of each color are driven so that ON / OFF is the same, so that each color has 16 levels.

On the other hand, areas 1000 and 1001 surrounded by broken lines, which are smaller area units, are a red area and a green area, respectively.
It has three regions, a reen region and a blue region. The regions 1002 and 1003 surrounded by broken lines are two Red
Area, two Green areas, and two Blue areas, for a total of six areas. Therefore, an area 1000 surrounded by a broken line,
1001 can be pixels that take two levels for each color. Further, regions 1002 and 10 surrounded by broken lines
03 can be pixels that take four levels for each color.

As described above, one display can display a plurality of different resolutions.

[0018]

However, when an image captured by a high-resolution scanner or the like is displayed at a high resolution using the above-described image configuration capable of a plurality of resolutions, characters included in a monochrome text image are displayed. In outlines, etc., the high resolution is effective, but on the other hand,
On the other hand, in the case of relatively flat intermediate colors or the skin portion of a person having a gentle gradient of color change, there is a problem that the image quality is deteriorated due to a decrease in the number of colors.

The present invention has been made in view of the above conventional example, and is an image processing apparatus for an image display apparatus having a plurality of pixels each of which can independently control a display state. An object of the present invention is to provide an image processing method and an image processing method capable of displaying an image of high quality.

[0020]

In order to achieve the above object, an image processing method and apparatus according to the present invention have the following arrangement. That is, an image processing method for an image display device having a plurality of pixels each of which can independently control a display state, comprising: an input step of inputting image data; and a predetermined number of pixels of the image data input in the input step. A halftone processing step in which halftone processing is performed with a small number of display colors if an edge is included in a neighboring pixel block, and a halftone processing is performed with a large number of display colors if no edge is included, and And displaying a tone-processed image.

According to another aspect of the present invention, there is provided an image processing apparatus for an image display apparatus having a plurality of pixels each of which can independently control a display state, wherein input means for inputting image data; Halftone processing means for performing halftone processing with a small number of display colors if edges are included in neighboring pixel blocks of a predetermined number of pixels of input image data, and performing halftone processing with a larger number of display colors if no edges are included; Display means for displaying an image halftoned by the halftone processing means.

According to another aspect of the present invention, there is provided a computer program product for performing computer-readable program code means for performing image processing of an image on an image display device having a plurality of pixels each of which can independently control a display state. Wherein the computer program product comprises: a first computer readable program code means for inputting image data; and a neighborhood of a predetermined number of pixels of the image data input by the first program code means. Computer-readable second program code means for performing halftone processing with a small number of display colors if the pixel block includes an edge and performing halftone processing with a large number of display colors if no edge is included, and the second program A computer displaying a halftone processed image Data and a readable third program code means.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an image processing method according to an embodiment of the present invention and points of the processing will be summarized, and then a detailed description thereof will be given. An image processing method and an image processing method according to an embodiment of the present invention include a display including an array of a plurality of pixels each of which can independently control a display state, and an image signal transferred from an image signal source, and An image processing method including a display interface that converts a signal into a signal that can be input and displayed by a display and outputs the converted signal, wherein the display has a plurality of pixel formats characterized by the number of display colors and the pixel density. The display interface has a type, and selectively performs image processing based on one of a plurality of pixel formats according to a local feature in an image represented by an input image signal, thereby obtaining an image. Depending on the characteristics of each part, halftone processing can be performed with priority given to either resolution or number of colors. That.

Hereinafter, an image processing method according to an embodiment of the present invention and its processing will be described in detail. In the present embodiment, TC
This is a color page display system that connects to a network using the P / IP protocol and emulates a dumb printer. FIG.
FIG. 1 is an overall configuration diagram illustrating a display system according to an embodiment of the present invention, and arrows indicate a flow of information.

Image communication input I / F (interface) 1
1 receives high definition image data from a network.
The image communication input I / F 11 has address information on the network assigned to the present system, captures a data packet sent to the network for this address, and reconstructs the original completed image data and the like. With the ability to

The communication buffer 12 has an image communication input I / F.
11 temporarily stores the received image signal and buffers the difference between the previous and next data flow speeds. This communication buffer 1
The image signal which has passed through 2 is transferred to the line buffer 13, where it is once stored. This image signal has R, G, and B channels.
It is written together.

FIG. 9 shows an example of a specific configuration of the line buffer 13. Reference numeral 131 denotes a FIFO (First in First out) buffer constituted by a shift register.
Data of N lines (N = 0, 1, 2,...) Is input from the communication buffer, and buffering of the FIFO operation is performed. Then, the shifted data is sent to the shift buffer 132.

Data of (2N + 1) lines (N = 0, 1, 2,...) Is sequentially input to the line 134, and the input data is sent to the shift buffer 133. As a result, four pixels in the vicinity are stored in the shift buffers 132 and 133. Next, the neighboring four pixel data is transferred to the edge detection circuit 16. FIG. 9 shows R, G, B
The circuit configuration for one channel out of each channel is shown. However, if three channels are prepared and four neighboring data corresponding to each channel are sent to the edge detection circuit 16 and the halftone processing circuit 14, respectively. , R, G, B channels.

In the edge detection circuit 16, as described above, the line buffer 13 (shift buffers 132 and 133)
, Receive neighboring 4 pixel data corresponding to each channel, and independently check whether an edge exists in each of the R, G, and B channels using a predetermined algorithm. As this algorithm, for example, an absolute value of a mutual difference between four neighboring values is obtained, and a total of six values obtained as a result are compared with a prescribed threshold value. Then, if there is one larger than the threshold value, it is determined that an edge exists.

Here, the threshold value is, for example, 128. The maximum value and the minimum value of the pixel data are 2
55, 0. The edge detection circuit 16 outputs the result of checking the presence / absence of an edge to the pixel format selection circuit 17 as an edge detection signal.
In the pixel format selection circuit 17, R, G, B
, And if any one edge is detected, a pixel format selection signal for selecting a high-density format is output to the halftone processing circuit 14.

Conversely, if no edge is detected, a pixel format selection signal for selecting a low density format is output. On the other hand, in the present embodiment, a case where an FLCD display 20 as shown in FIG. 7 is used as a display will be described. In this configuration, when the low-density pixel format is used, the entire pixel shown in FIG. 7 is treated as one pixel. The color of a pixel in the low-density pixel format is determined by a combination of on / off of each color area within a solid line in FIG.

Here, as in the case of FIG. 4, the FLCD display is driven such that the upper and lower sub-pixel pairs of each color take the same display state. Therefore, the effective pixel area division ratio is 1: 2: 4: 8 for each color, and the number of gradations of each color in the pixel remains unchanged at 1
With 6 gradations, a total of 4096 colors can be displayed.

The halftone processing circuit 14 receives either a high-density or low-density pixel format selection signal from the pixel format selection circuit. Then, it receives from the line buffer 13 a data set of 4 neighboring 2 × 2 pixels which is the same as that received by the edge detection circuit 16, and according to the pixel format specified by the input pixel format selection signal, And outputs a corresponding halftone processing result.

The halftone processing method performed by the halftone processing circuit 14 will be described below. When the high-density format is specified, the halftone processing is closest to the input pixel data,
A so-called simple multi-value conversion method of outputting a displayable value of the pixel is used. 11A and 11B
11 is a diagram showing a corresponding output example when an image as shown in FIG. 10 is input. FIG. 11B shows the result of simple multi-level conversion in a high-density format. FIG. 11A is for reference.
The result of simple multi-level conversion in the low-density format is shown.

However, the low-density format uses a value obtained by averaging a plurality of (four in this example) input values contained in one low-density pixel in order to process at low density. In the drawing, the sub-pixels with patterns indicate the lighting state. When the high-density pixel format is selected by the pixel format selection circuit 17, 2
All of the × 2 four neighboring pixels are processed by the above method.

On the other hand, the pixel format selection circuit 1
When the low-density pixel format is selected according to 7, the processing is performed using the method described with reference to FIG. 11A, that is, the average value of the input values included in the low-density pixels.
As shown in FIG. 10, the size of the area corresponding to one low-density pixel is four times the size of the area corresponding to one high-density pixel.

FIGS. 13A and 13B show processing results in the case of a one-dimensional gradation image as shown in FIG. FIG. 13A shows the result of processing in the low-density format, and FIG. 13B shows the result of processing in the high-density format. As described above, in the high-density format, the gradation expression capability of each pixel is reduced, so that the luminance actually lit suddenly changes around the threshold value, and is not suitable for halftone expression. .

On the other hand, the low-density format has a high gradation display capability. Further, in the processing in the low-density format, if a pseudo halftone processing represented by a dither method is added, the gradation can be further improved. FIG.
Is an image in which the line drawn in FIG. 10 is superimposed on the image in FIG. When the embodiment according to the present invention is applied to this image, if no edge is included in the low-density pixels, quantization is performed based on the number of gradations having low-density pixels (here, 16 gradations). .

On the other hand, when an edge is included, quantization is performed based on the number of gradations (here, 2 or 4 gradations) of the high-density pixel. However, here, simple quantization is used as a quantization method. The result is shown in FIG. On the other hand, the result of quantizing all pixels in the high-density pixel format and, conversely, the result of quantizing all pixels in the low-density pixel format are shown in FIG.
6, shown in FIG.

Here, comparing FIG. 15 with FIGS. 16 and 17, FIG. 15 shows a color having a small error from the input value in the background portion where the pixel value changes slowly while maintaining the outline of the line. It can be seen that the expression has been obtained. As is well known, the dither method is widely used in an output device having a limited output value as a method of obtaining a halftone expression in a pseudo manner by utilizing human visual characteristics. In this method, a plurality of thresholds having a certain distribution are associated with each pixel position using a threshold matrix or the like, and a halftone expression is obtained by simply comparing the threshold with the magnitude of an input value. Do.

FIG. 18 shows a matrix called a 4 × 4 Bayer type as an example of a matrix for associating thresholds with pixel positions. Since such a threshold matrix is smaller than a normal image size, it is periodically made to correspond to pixels in a tile shape. The numbers in the figure represent the order of the smaller threshold values at the position, and the actual threshold values depend on the number of tones of the output means (for example, a printer) or the number of tones to be expressed. It will be different.

The memory controller 15 writes the data output from the halftone processing circuit 14 to a designated position in the frame buffer 18. At the same time, the control of reading out the data of the line requested by the scanning control circuit 19 from the frame buffer 18 and transferring the data is performed. The scanning control circuit 19 uses a non-interlaced drive to
To update or refresh the display of 20,
The necessary display data is obtained from the frame buffer 18 line by line via the memory controller 15 and
Transfer to LCD20.

The operation speed of the FLCD 20 changes depending on temperature conditions and the like, so that the time required for updating one line is not always constant. For this reason, the display side designates whether or not to accept the transfer of display data of a new line from the display side, that is, a so-called device busy signal is used. And the transfer is resumed from the line where the busy signal was activated.

The blocks 11 to 19 shown in FIG.
2 is controlled by a microprocessor 21 incorporated therein. Next, an example in which the processing configuration of FIG. 8 is realized by software will be described with reference to FIG. The program corresponding to the flowchart in FIG. 19 is stored in the ROM 22 in advance, and is interpreted and executed by the CPU 21.

In step S1, the image communication input I / F1
1 to input a processed image. In step S2, the input image is divided into blocks of a predetermined size, a block number is assigned to each block, and the block number n is initialized (n = 1). In step S3, it is determined whether or not an edge exists in block n. If there is, the process proceeds to step S4. If not, the process proceeds to step S5.

In step S4, the above-described high-density format is selected, and the above-described intermediate processing corresponding to this format is performed. Then, the processing result is stored in the frame buffer 18. On the other hand, in step S5, the above-described low-density format is selected, and the above-described intermediate processing corresponding to this format is performed. Then, the processing result is stored in the frame buffer 18.

In step S6, it is determined whether or not the processing for all blocks has been completed. If the processing has not been completed, the block number n is incremented by one in step 7, and the process returns to step S3 to repeat the same processing. If it has been completed, the process proceeds to step S8. In step S8, an image corresponding to the FLCD is displayed based on the image data stored in the frame buffer 18.

The line buffers shown in FIGS.
Although an example in which buffering is performed in units of four neighboring pixels of the size of x2 has been described, it is needless to say that buffering may be performed in units of neighboring pixels of other sizes. For example, 3
Buffering may be performed in units of 9 pixels in the vicinity of the size of x3, and edge detection may be performed at that size. In this case, in the configuration of the line buffer 13 shown in FIG.
Obviously, it is sufficient to adopt a configuration in which another circuit 31 is added.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and can be applied to a single device (for example, a copier, Facsimile machine, etc.). Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus to store the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in the program.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Examples of a storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, and C
A D-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium. That is, the "image input module" corresponding to the processing of step S1 for inputting an image, and the step S for determining high / low density based on whether an edge exists in a block unit.
A "high / low density determination module" corresponding to the processing of step 3; a "low density format intermediate processing module" corresponding to the processing of step S5 for performing intermediate processing in the low density format;
The program codes of the "high-density format intermediate processing module" corresponding to the processing of step S4 for performing the intermediate processing in the high-density format and the "FLCD display module" corresponding to the processing of step S8 for displaying the intermediate processing result on the FLCD are stored. What is necessary is just to store it in a medium.

According to the embodiment of the present invention, a pixel format having a higher density is used in a portion having a high edge in an image, and a pixel format having a high gradation is used in a portion having a weak edge and a gradual change in luminance. Keying process and display the results. As a result, the resolution of the display with pixel division is fully demonstrated, and excellent display is achieved, which achieves both smooth contours and fineness in characters and fine lines, and rich color expression in halftone parts with little change in luminance. Become.

[0055]

As described above, according to the present invention, inexpensive and high-quality image display is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a 1: 2 pixel division.

FIG. 2 is a diagram showing a difference between equal pixel division and pixel division by a power-of-two sequence.

FIG. 3 is a diagram showing a shift in the center of gravity of a lighting pixel due to a change in luminance in pixel division.

FIG. 4 is a diagram illustrating an example of pixel division with a small center of gravity shift.

FIG. 5 is a diagram illustrating a barycenter shift of pixel division with a small barycenter shift.

FIG. 6 is a diagram illustrating an example of pixel division in which the center of gravity is further moved.

FIG. 7 is a diagram illustrating an example of a sub-pixel configuration in a pixel that enables a plurality of pixel densities.

FIG. 8 is a configuration example of an embodiment according to the present invention.

FIG. 9 is a diagram showing a configuration of a line buffer.

FIG. 10 is a diagram illustrating hatched data based on a high-density pixel pitch.

11A is a diagram showing a result of processing the image of FIG. 10 based on low-density pixels.

FIG. 11B is a diagram showing a result of processing the image of FIG. 10 based on high-density pixels.

FIG. 12 is a diagram showing a luminance distribution of a one-dimensional gradation image.

13A is a diagram showing a result of processing the image of FIG. 12 based on low-density pixels.

13B is a diagram showing a result of processing the image of FIG. 12 based on high-density pixels.

14 is a diagram showing an image in which the line drawn in FIG. 10 is superimposed on the image in FIG.

FIG. 15 is a diagram showing a result of a simple multi-value processing based on the presence or absence of an edge with respect to the image of FIG. 14;

FIG. 16 is a diagram showing a result of a simple multi-value processing based on high-density pixels with respect to the image of FIG. 14;

FIG. 17 is a diagram showing a result of a simple multi-value processing based on low-density pixels with respect to the image of FIG. 14;

FIG. 18 is a diagram illustrating an example of a dither matrix.

FIG. 19 is a flowchart showing a processing procedure of image processing according to the present invention.

20 is a diagram showing an example of a layout in which a program corresponding to the flowchart of FIG. 19 is stored in a predetermined computer-readable recording medium.

[Explanation of symbols]

 Reference Signs List 11 Image communication input I / F 12 Communication buffer 13 Line buffer 14 Halftone processing circuit 15 Memory controller 16 Edge detection circuit 17 Pixel format selection circuit 18 Frame buffer 19 Scan control circuit 20 FLC display

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 5/00 520 G09G 5/02 L 5/02 G06F 15/68 320A

Claims (11)

[Claims] 1. An image processing method for an image display device having a plurality of pixels, each of which can independently control a display state, comprising: an input step of inputting image data; A halftone processing step of performing halftone processing with a small number of display colors if the edge is included in a neighboring pixel block of a predetermined number of pixels, and performing a halftone processing with a large number of display colors if no edge is included; A display step of displaying an image subjected to halftone processing in the step. 2. The size of the neighboring pixel block is 2 ×
2. The image processing method according to claim 1, wherein 3. The size of the neighboring pixel block is 3 ×
3. The image processing method according to claim 1, wherein 4. The image processing method according to claim 1, wherein one pixel of the image display device is composed of a plurality of size areas. 5. The halftone processing step includes: setting a smaller area with a smaller display color number as one pixel area by including an edge in a neighboring pixel block having a predetermined number of pixels of the image data input in the input step; 2. The image processing method according to claim 1, wherein if no edge is included, a halftone process is performed in which a larger area with a larger number of display colors is set as one pixel area. 6. An image processing device for an image display device having a plurality of pixels each capable of independently controlling a display state, comprising: an input unit for inputting image data; Halftone processing means for performing halftone processing with a small number of display colors if edges are included in neighboring pixel blocks having a predetermined number of pixels, and performing halftone processing with a large number of display colors if no edges are included; Display means for displaying an image subjected to halftone processing by the means. 7. The size of the neighboring pixel block is 2 ×
7. The image processing apparatus according to claim 6, wherein 8. The size of the neighboring pixel block is 3 ×
7. The image processing apparatus according to claim 6, wherein the number is 3. 9. The image processing device according to claim 6, wherein one pixel of the image display device is formed of a plurality of size areas. 10. The halftone processing means, wherein, if an edge is included in a predetermined number of neighboring pixel blocks of the image data input by the input means, an area having a smaller number of display colors and a smaller area is defined as one pixel area. 7. The image processing apparatus according to claim 6, wherein if no edge is included, a halftone process is performed in which a larger area with a larger number of display colors is set as one pixel area. 11. A computer program product, comprising computer readable program code means for performing image processing of an image on an image display device having a plurality of pixels each capable of independently controlling a display state. Computer program product, comprising: computer-readable first program code means for inputting image data; and an edge defined by a predetermined number of pixels of the neighboring pixel block of the image data input by the first program code means. If it is included, halftone processing is performed with a small number of display colors.
Performing a halftone process with a larger number of display colors, displaying a computer-readable second program code means and an image halftone-processed by the second program code means,
Computer program product, comprising: a third program code means readable by a computer.