JPH04349780A - Device and method for outputting picture data - Google Patents

Abstract

PURPOSE:To realize the picture output device able to output a picture having natural gradation without missing of detailed information such as character information even when a picture data of a wide range is outputted. CONSTITUTION:An area designation means 2 sets an area 1 in the inside of a bit map memory 1 whose longitudinal/lateral picture element number is respectively M1, M2. Position information representing a longitudinal and a lateral position of the area 1 to an area 0 is generated, them a multi--value processing means 3 sets the area 1 whose longitudinal/lateral picture element number is respectively M1/N1, M2/N2 to the inside of the bit map memory 1 and reads the data and generates one multi-value data corresponding to a mean value of the brightness of the area 1 and in the vicinity of the area 1 from the binary picture data including and in the vicinity of the area 1. Then a gamma correction means 4 applies gamma correction to the multi-value data, and the resulting multi-value picture data is outputted to a frame memory 5, and a CRT 6 displays it.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention converts a binary image inputted by an image input means such as an image scanner or calculated by a computer into multivalued image data, and converts the binary image into multivalued image data, which can be used on a display, a printer, etc. The present invention relates to an image data output device and an image data output method for outputting to an output device capable of outputting multivalued data.

0002

2. Description of the Related Art In recent years, binary image data has been input using an image input device such as an image scanner, displayed on a display device, edited, or stored in an external storage device such as a magnetic disk or optical disk. There is a growing need for image data output devices such as image filing systems that manage binary image data and perform various processes such as outputting this binary image data to a display or printer as needed. An example of such a conventional image data output device is one described in Japanese Patent Publication No. 3-3256.

An example of a conventional image output device will be described below with reference to the drawings. FIG. 7 shows a block diagram of a conventional image output device. In Figure 7, 10
0 is the central processing unit (hereinafter referred to as CP) that controls the overall operation.
(referred to as U). 101 is a cold cathode tube display device (hereinafter referred to as CRT) which is an image output device; 102 is a CPU
The main memory 103 is an image memory for displaying images, and is provided on the display device side separately from the main memory 102. Note that there is also an image output device that does not have the image memory 103 and stores image data in the main memory 102, and current personal computers mainly adopt the latter, but here, the image output device stores the image data in the image memory 103, A description will be given of how this is represented on a display device. 104 is an image scanner, 105 is a scanner interface (hereinafter referred to as scanner I/F), and the image scanner 10
The binary image data read from 4 is transferred to the image memory 103 via the scanner I/F. 106 is an external storage device such as a magnetic disk device or an optical disk device; 107
is an external storage device interface (hereinafter referred to as external storage I/F)
Data read from the image scanner 104 is stored in an external storage device 106, and read out to the image memory 103 as needed.

The operation of the conventional image output device configured as described above will be explained. When outputting an input image read from the image scanner 104 to the CRT 101, there are two cases in which the image data is thinned out so that the entire layout can be checked and the entire screen is displayed at once (hereinafter referred to as thinned display mode), and a case in which a portion of the original image is displayed. Two methods are used when displaying a portion without thinning it out (hereinafter referred to as direct display mode).

Generally, when editing a part of an input image by moving, enlarging, reducing, rotating, etc., a thinning display mode is used in which the entire layout can be checked. Thinning methods include sampling the original image data at regular intervals, dividing the original image space into many small areas, and if there is even one black pixel in each small area, that small area is reduced to one black pixel. There is an OR method using pixels.

[0006]

[Problem to be Solved by the Invention] However, with the above configuration, when displaying an image in the thinning display mode for checking the entire display, the binary image data is simply thinned out and the binary image data is Therefore, if you output an image such as image data obtained by scanning a wide area of a text document with an image scanner, the details of the document will be blurred and you will not be able to visually confirm the text. Ta. Therefore, in order to be able to visually check the details of an image, the only way to do so is to reduce the amount of data thinning to display a narrower area, or even switch to image direct display mode to check a small part of the image. There is no method for this, and the problem is that it is not possible to view a wide range of image data and output detailed information of the image in a state that can be visually confirmed.

[0007] In view of the above-mentioned problems, the present invention is capable of outputting images with natural gradation without missing detailed information such as text information, while outputting image data over a wide range. The first objective is to provide an image output device.

A second object of the present invention is to provide an image output device capable of outputting clear images.

A third object of the present invention is to provide an image output device that is simple and capable of high-speed processing.

0010

[Means for Solving the Problems] In order to achieve the above first object, the image output device of the present invention has M1 and M2 pixels in the vertical and horizontal directions, respectively (M1 and M2 are M1≧2 and M2).
2≧2 natural numbers) is defined as area 0, and the number of vertical and horizontal pixels within area 0 is M1/N1, respectively.
pieces, M2/N2 pieces (N1, N2 are M1>N1≧1 and M
2>N2≧1 (a natural number), and outputs position information indicating the vertical and horizontal positions of region 1 in region 0, and binary image data in the vicinity including region 1. multi-value conversion means for generating one piece of multi-value data corresponding to the average value of brightness in the vicinity including area 1 from , and γ-correction means for performing γ correction on the multi-value data and outputting multi-value image data; The first feature is that the apparatus includes an output means for visualizing a multi-value image having N1 and N2 pixels in the vertical and horizontal directions by outputting the multi-value image data according to the position information obtained from the area specifying means. That is.

[0011] Also, in order to achieve the second objective, the multi-value converting means generates one piece of multi-value data corresponding to the average value of the brightness of the region 1 from the neighboring binary image data including the region 1. a binary data detection means for detecting binary image data in the vicinity including the region based on the position information of the region 1 from the region specifying means; and a vertical spatial frequency of the binary image data in the vicinity including the region 1. By setting the cutoff frequency of the horizontal spatial frequency to be less than or equal to N1/M1 of the sampling frequency of the binary image data, and the cutoff frequency of the horizontal spatial frequency to be less than or equal to N2/M2 of the sampling frequency of the binary image data, it is possible to a low-pass filter means for converting binary image data into a multi-value data group corresponding to region 1; and a low-pass filter means for converting binary image data into a multi-value data group corresponding to area 1; A second feature of the present invention is that it is equipped with a thinning means for outputting multivalued data.

Furthermore, in order to achieve the third objective, the multi-value converting means generates one piece of multi-value data corresponding to the average value of the brightness of the region 1 from the neighboring binary image data including the region 1. Based on the positional information of the area 1 from the area specifying means, a binary data detection means detects the binary image data of the area 1, and the number N of binary image data detected by the binary data detection means is detected. pixel number detection means, white pixel number detection means for detecting the number Xk of white pixels of the binary image data detected by the binary data detection means, and multivalued data corresponding to the neighboring binary image data including area 1. A third feature of the present invention is that it is equipped with multi-value data output means for outputting a multiple of Xk/N.

[0013]

[Operation] According to the above-mentioned first feature, the present invention reduces the number of pixels while converting binary image data into multi-value data, applies γ correction to this data, and then provides an output means capable of multi-value output. By outputting, more information can be output per unit pixel of the output means, so while outputting a wider range of image data than when outputting binary image data by thinning it, text information etc. It is possible to output an image without missing detailed information.

[0014] This is because if binary image data is simply thinned out and displayed, detailed information in the image will be completely lost and fine text will be lost, whereas when binary image data is displayed as a binary image. By generating multivalued data corresponding to the average luminance of the data, detailed information that is missing in conventional devices can be preserved as tone information of output pixels.

Furthermore, in devices that handle such multivalued image data, the image γ (γ=0.45
) is used. Furthermore, when outputting a multivalued image to an output means such as a CRT or video printer, if the multivalued data corresponding to the average luminance of the binary image data described above is used as is, these data will be affected by the image γ. Since the data is linear and has no natural gradation, the output will not have natural gradation. Therefore, by using the γ correction means to perform γ correction on the multi-value data corresponding to the average luminance of the binary image data to obtain multi-value image data, it is possible to obtain a natural gradation when outputting the image to the output means. Enables output with tonality.

According to the second feature, the image data can be simply thinned out and displayed by applying a low-pass filter that limits the cutoff frequency of the spatial frequency of the image to the original binary image data. This reduces the occurrence of aliasing distortion that occurs when printing images, and enables clear image output.

Furthermore, according to the third feature, multi-value data is generated through simple processing of counting the number of white pixels in the binary image area 1 and performing integer operations, thereby enabling simple and high-speed processing. It is possible to provide an image output device.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

[0019] In the following embodiment, M1/N1=2
, M2/N2=2, for example, will be described.

FIG. 1 is a block diagram showing the configuration of an image data output device according to a first embodiment of the present invention. The bitmap memory 1 holds binary image data (hereinafter referred to as area 0) having M1 (ie, N1×2) and M2 (ie, N2×2) pixels in the vertical and horizontal directions, respectively. The area specifying means 2 sequentially sets areas 1 each having 2×2 pixels in the vertical and horizontal directions within the bitmap memory 1, and outputs the position information thereof. The multi-value conversion means 3 reads the bitmap memory 1 according to the position information of the area 1 outputted by the area specifying means.
Set area 2, which includes area 1 and has 3 x 3 pixels in the vertical and horizontal directions, read the 9 binary image data included in this, and then calculate 1 corresponding to the average brightness of area 2.
This method generates multiple multivalued data.

The γ correction means 4 performs γ correction processing on the multi-value data to generate multi-value image data. The frame memory 5 stores the multivalued image data generated by the γ correction means 4 at a predetermined address in accordance with the positional information of the region 1 outputted by the region specifying means 2. Note that the frame memory 5 is configured to be able to hold at least N1×N2 multivalued image data. The CRT 6 visualizes the multivalued image data stored on the frame memory 5. Frame memory 5 and C
RT6 forms an image output means.

In the configuration described above, the area specifying means 2
However, by sequentially specifying area 1 inside area 0 of bitmap memory 1, the multivalued image data corresponding to area 1 is sequentially stored in frame memory 5, and finally, the multivalued image data corresponding to area 0 Multivalued image data having N1×N2 pixels is stored on the frame memory 5 and visualized on the CRT 6.

Hereinafter, the area specifying means 2, the multi-value converting means 3, γ
Taking as an example the case where the correction means 4 is executed by software by a microcomputer (not shown), the details of the operation of each means will be explained.

FIG. 2 is a flowchart illustrating the operation of the area specifying means 2. When the operation starts, first step S
As shown in 1, counter variables i and j are initialized to 0. Next, in step S2, variables x and y representing the coordinates of the upper left pixel of area 1 are set to x←2×i, y←2.
xj is respectively substituted, and in step S3, the variables x and y are output to the multi-value conversion means 3. Then, in step S4, wait until multi-value image data corresponding to area 1 is generated, and then, in step S5, i, j representing the coordinates on the frame memory 5 of the multi-value image data generated are stored in the frame memory 5. Output. And in step S6 i
It is determined whether or not is N1-1, and when i≠N1-1, 1 is added to i in step S7, and the process returns to step S2.

When i=N1-1, i is initialized to 0 in step S8, and then it is determined in step S9 whether j is N2-1. When j≠N2-1, 1 is added to j in step S10, and the process returns to step S2. When j=N2-1, it means that the entire range of area 0 has been specified, and the operation is ended.

FIGS. 3(a), 3(b), and 3(c) are diagrams for explaining the operation of the multivalue converting means 3 of the first embodiment. Figure 3 (a
) is a block diagram showing the configuration of the multi-value conversion means, and 7 is a block diagram showing the configuration of the multivalue conversion means.
A value data detection means, 8 a low-pass filter means, and 9 a thinning means. Further, FIG. 3(b) is a flowchart illustrating the operation of the binary data detection means. The binary data detection means first detects area 1 as shown in step S11.
x and y representing the coordinates of the upper left pixel are input from the area specifying means 2. From this, the multivalue conversion means 3 determines that the coordinates on the bitmap memory 1 are (x, y) and (x
+1, y), (x, y+1), (x+1, y+1) 2
It is determined that value image data has been specified. Next step S
At step 12, an operation is performed to read the binary image data group of the area including area 1 from the bitmap memory 1. Specifically, 3x3 binary image data in which the point on bitmap memory 1 whose coordinates are (x, y) is the upper left corner and the point whose coordinates are (x+2, y+2) is the lower right corner are bit-shaped. It is read from map memory 1.

Next, the low-pass filter means 8 applies a low-pass filter to each binary image data to generate the same number of data. It is assumed that what is output at this time is data with a length of 16 bits per pixel.

Furthermore, in this embodiment, M1/N1=2, M
Since the number of pixels is converted to 2/N2=2, the cutoff frequency of the vertical spatial frequency of the binary image data is set to 1/2 or less of the sampling frequency of the binary image data, and the cutoff of the horizontal spatial frequency is set to 1/2 or less of the sampling frequency of the binary image data. A low-pass filter whose frequency is 1/2 or less of the sampling frequency of binary image data may be used. FIG. 4 is a characteristic diagram showing the spatial frequency characteristics in the horizontal direction of an image, and the characteristics of the low-pass filter means 8 will be explained using FIG. In Figure 4, the horizontal axis represents the spatial frequency and the vertical axis represents the gain, and the broken line in the figure is characteristic A that represents the range of the spatial frequency characteristics of the original binary image data, which is the characteristic of the actual binary image. The spatial frequency characteristics are
The curve falls within the range surrounded by this broken line and the vertical and horizontal axes of the graph.

Characteristic B shown by a solid line indicates the spatial frequency characteristic of image data obtained by applying a low-pass filter to characteristic A. Therefore, the result of applying a low-pass filter to the binary image data is a curve that falls within the range surrounded by this solid line and the vertical and horizontal axes of the graph. Also, fs is the sampling frequency of the original binary image data, f
c is the cutoff frequency of the low-pass filter, and the low-pass filter means has a characteristic that satisfies fc≦fs/2. Two low-pass filters with these characteristics
By multiplying the value image in both the vertical and horizontal directions, aliasing distortion that occurs later when the image is thinned out and the spatial frequency is set to fs/2 can be reduced. (In addition, in the spatial frequency characteristic curve, the spatial frequency is fs/
2 or more portions become the aliasing distortion that occurs during thinning.) FIG. 3(c) is a flowchart for explaining the operation of the thinning means 9. The thinning means 9 selects and outputs one piece of data from the 3×3 pieces of data generated by the low-pass filter means 8. Specifically, the generated 3 x 3 data is s (x, y) (x, y is 0≦x
≦2, 0≦y≦2 (an integer), in step S13, these data are sequentially read and whether or not the data is s(1, 1) corresponding to the pixel at the center position is determined in step S13. A determination is made in S14. If the data is s(
1, 1), the data is output in step S15 and the process ends.

Next, FIG. 5 is a flowchart illustrating the operation of the γ correction means which generates multi-value image data by multiplying multi-value data by image γ. First, step S1
6, the 16-bit data s output by the multi-value conversion means
Next, in step S17, γ correction processing is performed, and the result is output as 8-bit data D. As the γ correction processing at this time, γ=0.45 processing is performed. Specifically, the calculation D=s0.45 is performed. And finally step S1
8, 8-bit long multivalued image data D is output.

As described above, according to the first feature of this embodiment, the number of vertical and horizontal pixels is M1 and M2 (M2), respectively.
1, M2 is a natural number where M1≧2 and M2≧2) Binary image data is defined as area 0, and inside area 0, the number of vertical and horizontal pixels is M1/N1 and M2/N2 (N1, N2, respectively).
2 is a natural number where M1>N1≧1 and M2>N2≧1)
area setting means for setting area 1, and outputting position information indicating the vertical and horizontal positions of area 1 in area 0;
Multi-value conversion means for generating one piece of multi-value data corresponding to the average value of brightness in the vicinity including area 1 from binary image data in the vicinity including area 1; and a multi-value image by performing γ correction on the multi-value data. γ correction means for outputting data; and output means for visualizing a multivalued image having N1 and N2 pixels in the vertical and horizontal directions by outputting the image multivalued data according to the position information obtained from the area specifying means. By providing , more information can be output per unit pixel of the output means.
While outputting a wider range of image data than when binary image data is thinned out and output, it is possible to output an image without missing detailed information such as character information.

According to the second feature of this embodiment, the multi-value conversion means converts one piece of multi-value data corresponding to the average value of the luminance of the region 1 from the neighboring binary image data including the region 1. In order to generate the image, a binary data detection means detects the binary image data in the vicinity including the area based on the position information of the area 1 from the area specifying means, and a vertical detection means for detecting the binary image data in the vicinity including the area 1. Area 1 can be achieved by setting the cutoff frequency of the spatial frequency in the direction to be less than or equal to N1/M1 of the sampling frequency of the binary image data, and the cutoff frequency of the spatial frequency in the horizontal direction to be less than or equal to N2/M2 of the sampling frequency of the binary image data. a low-pass filter means for converting neighboring binary image data including region 1 into a multi-value data group corresponding to region 1; By being equipped with a thinning means for outputting one multivalued data within the image data, it is possible to reduce the occurrence of aliasing distortion that occurs when displaying image data by simply thinning it out, and to output a clear image. It can be done.

Next, a second embodiment of the present invention will be explained. Note that the device of this embodiment is basically as shown in FIGS. 1 and 2.
Since this embodiment is similar to the first embodiment shown in FIG. 5, the description will focus on the multi-value conversion means, which is a feature of this embodiment.

FIG. 6 is a block diagram showing the configuration of the multivalue converting means of the second embodiment. The operation of the multi-value converting means of the second embodiment will be described below with reference to FIG.

The binary data detection means 7 performs processing by software, as in the first embodiment described above. In addition,
The binary data detecting means 7 of this embodiment inputs x, y representing the coordinates of the upper left pixel of the region 1 from the region specifying means 2, and from this, the coordinates on the bitmap memory 1 as the region 1 are (x , y), (x+1, y), (x, y+1), (
x+1, y+1) binary image data is read and sequentially output. A pixel number counter 10 serving as a pixel number detection means receives 2 output from the binary data detection means 7.
Count the number N of value data and output the result. A white pixel counter 11, which is a white pixel number detection means, counts the number Xw of binary data indicating white pixels outputted from the binary data detection means 7, and outputs the result.

Further, the arithmetic unit 12 calculates Xk/N from N and Xk, and outputs this as 16-bit multi-value data.

As described above, the multivalue converting means includes a binary data detecting means for detecting binary image data of the area 1 based on the position information of the area 1 from the area specifying means, and a binary data detecting means. The number N of binary image data detected by
pixel number detection means for detecting the number of white pixels Xk of the binary image data detected by the binary data detection means; By providing a multi-value data output means that outputs a multiple of Xk/N as multi-value data, multi-value data can be generated by simple processing of counting the number of white pixels in the binary image area 1 and performing integer operations. This makes it possible to provide an image output device that can perform simple and high-speed processing.

[0038] Although the case where the area specifying means, multi-level conversion means, γ correction means, etc. are realized by software has been described, each means may be constructed by a circuit that performs the same operation, or may be implemented by a circuit. The configured means and
It is also possible to have a configuration in which a combination of means realized by software processing is used.

Furthermore, the γ correction means may refer to a table prepared in advance instead of using calculations. Note that by using a method of referring to a table, it is possible to perform the γ correction process even faster.

Furthermore, the operation of the multi-value converting means is not limited to these embodiments, and multi-value converting means using other methods may also be used.

[0041] Furthermore, in these embodiments, M1, M
Although 2, N1, and N2 are treated as constants, a setting means for setting these values may be provided.

Furthermore, although the binary image data is stored in the bitmap memory, binary data obtained directly from an external storage device, an image scanner, etc. may also be used.

[0043] In addition, although the multi-value image data was visualized by directly outputting it to the output means, it is also possible to output the multi-value image data to an external storage device or the like and then visualize it using the output device as necessary. Good too.

[0044] The output device is not limited to a CRT, but may also be a video printer that visualizes images by performing multi-level recording by depositing ink on recording paper.

[0045]

Effects of the Invention As described above, in the present invention, the number of vertical and horizontal pixels is M1 and M2, respectively (M1 and M2 are M1≧2 and M2).
2≧2 natural numbers) is defined as area 0, and the number of vertical and horizontal pixels within area 0 is M1/N1, respectively.
pieces, M2/N2 pieces (N1, N2 are M1>N1≧1 and M
2>N2≧1 (a natural number), and outputs position information indicating the vertical and horizontal positions of region 1 in region 0, and binary image data in the vicinity including region 1. a multi-value conversion means that generates one piece of multi-value data corresponding to the average value of brightness in the vicinity including region 1; a γ-correction means that performs γ-correction on the multi-value data and outputs multi-value image data; By outputting multivalued data according to the position information obtained from the area specifying means, the number of pixels in the vertical and horizontal directions can be reduced to N1.
By providing an output means for visualizing multivalued images of N2 and N2, it is possible to output a wide range of image data without missing detailed information such as character information, and to maintain natural gradation. It is possible to provide an image output device capable of outputting an image held by the user.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an image data output device according to an embodiment of the present invention.

[Fig. 2] Flowchart explaining the operation of area specifying means 2

FIG. 3: (a) Block diagram of multi-value converting means; (b) Flow chart explaining operation of binary data detecting means; (c) Flow chart explaining operation of thinning means.

[Figure 4] Characteristic diagram showing the spatial frequency characteristics in the horizontal direction of the image

[Figure 5
] Flowchart explaining the operation of the γ correction means

[Figure 6]
Flowchart explaining the configuration of the multi-value conversion means of the second embodiment

[Figure 7] Block diagram of a conventional image output device

[Explanation of symbols]

1 Bitmap memory 2 Area specification means 3. Multi-value conversion means 4 γ correction means 5 Frame memory 6 CRT 7 Binary data detection means 8 Low-pass filter means 9 Thinning means 10 Pixel number counter 11 White pixel counter 12 Arithmetic unit

Claims (5)

[Claims] [Claim 1] The number of vertical and horizontal pixels is M1 and M2, respectively.
(M1 and M2 are natural numbers where M1≧2 and M2≧2)
The binary image data is defined as area 0, and the number of vertical and horizontal pixels in area 0 is (M1/N1) and (M2/
N2) (N1, N2 are M1>N1≧1 and M2>N2
≧1 (a natural number), and set the area 1 where the area 0 is
area setting means for outputting positional information indicating the vertical and horizontal positions of the area 1; a multi-value conversion means for generating multi-value data; a γ-correction means for performing γ correction on the multi-value data and outputting multi-value image data; and position information obtained from the area specifying means for the image multi-value data. An image data output device comprising an output means for visualizing a multivalued image having N1 and N2 pixels in the vertical and horizontal directions by outputting according to the following. 2. The multilevel conversion means includes binary data detection means for detecting binary image data in the vicinity of the area 1, based on the position information of the area 1 from the area specification means, and the area 1. The cutoff frequency of the vertical spatial frequency of the neighboring binary image data is equal to or less than N1/M1 of the sampling frequency of the binary image data, and the cutoff frequency of the horizontal spatial frequency is the sampling frequency of the binary image data. a low-pass filter means for converting the binary image data in the vicinity including the area 1 into multi-value data by setting N2/M2 or less; 2. The image data output device according to claim 1, further comprising thinning means for outputting one multi-value data from said multi-value data group as data. 3. The multi-value conversion means is configured to convert two areas in the vicinity including area 1.
In order to generate one piece of multi-value data corresponding to the average value of the brightness of the area 1 from the value image data, the 2-value data of the area 1 is generated based on the position information of the area 1 from the area specifying means.
binary data detection means for detecting value image data;
pixel number detection means for detecting the number N of the binary image data detected by the value data detection means; and white pixel number detection means for detecting the number Xk of white pixels of the binary image data detected by the binary data detection means. 2. The image according to claim 1, further comprising a detection means and a multi-value data output means for outputting a multiple of Xk/N as the multi-value data corresponding to the binary image data in the vicinity including the area 1. Data output device. 4. The multi-value conversion means is configured to convert two neighboring regions including region 1 into two regions.
In order to generate one piece of multi-value data corresponding to the average density value of the area 1 from the value image data, the two values of the area 1 are determined based on the position information of the area 1 from the area specifying means.
binary data detection means for detecting value image data;
pixel number detection means for detecting the number N of the binary image data detected by the value data detection means; and black pixel number detection means for detecting the number Xk of black pixels of the binary image data detected by the binary data detection means. 2. The image according to claim 1, further comprising a detection means and a multi-value data output means for outputting a multiple of Xk/N as the multi-value data corresponding to the binary image data in the vicinity including the area 1. Data output device. [Claim 5] The number of vertical and horizontal pixels is M1 and M2, respectively.
(M1 and M2 are natural numbers where M1≧2 and M2≧2)
The binary image data is defined as area 0, and it is inside the area 0, and the number of vertical and horizontal pixels is M1/N1 and M2/N1, respectively.
N2 pieces (N1, N2 are M1>N1≧1 and M2>N2≧
1), and from the binary image data in the vicinity including the area 1, one piece of multi-value data corresponding to the average value of brightness in the vicinity including the area 1 is generated. , performs γ correction on the multi-value data to generate multi-value image data, and outputs the multi-value image data according to the position information of the area 1 corresponding to the multi-value image data, so that the number of vertical and horizontal pixels is N1, respectively. An image data output method for visualizing multivalued images of N2 and N2.