JP2015049631A - Image processing apparatus, image forming apparatus, image processing method, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine characters regardless of their small size.SOLUTION: An image processing apparatus includes a frequency conversion unit (302), a frequency analysis unit (303) that determines the intensities of spatial frequency components, and a determination unit (304) that compares, of the intensities of the spatial frequency components, the intensity of a high frequency component with a threshold, determines that the character size is small when the intensity is larger than the threshold, and determines that the character size is large when the intensity of the high frequency component is equal to or smaller than the threshold.

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, an image processing method, a program, and a recording medium that determine the size of characters included in image data.

  An image forming apparatus such as a scanner that scans a document and acquires image data, a copying machine equipped with a scanner, and a multifunction peripheral outputs an edge region in the image data when outputting or printing the image data obtained by scanning the document. Detect and perform enhancement processing on the detected edge region. By performing such enhancement processing, the reproducibility of the edge region in the output image is improved, so that the image quality of the output image can be improved.

  However, characters have various characteristics depending on their language system, font, size, color, or density. Some of these characters with various characteristics are difficult to detect as edges. On the other hand, some image quality deteriorates.

  When a filter is used for character processing, the character is thinned by a filter that emphasizes the character at a high frequency in order to increase resolution. Conversely, if the characters are made thicker, the resolution becomes weaker.

  Therefore, Patent Document 1 discloses a technique that can effectively emphasize thin characters included in image data separated into a base region. Specifically, the apparatus of Patent Document 1 extracts an RGB signal of a background area from an input RGB signal based on the input area identification signal, and a thin character is included in the extracted RGB signal. Detect whether a region exists. Next, spatial frequency conversion is performed on the detected thin character region, and the obtained spatial frequency component is analyzed to detect a frequency region corresponding to the character. Further, the emphasis processing is performed on the frequency region corresponding to the character, the spatial frequency is inversely transformed, and the image data is output again. This makes it possible to effectively emphasize only the character even in a region where a character with a low density that cannot be detected as an edge exists.

JP 2009-159089 A (published July 16, 2009)

  However, with the technique disclosed in Patent Document 1, even if a thin character can be detected as a character and an edge can be emphasized, a small character may still be erroneously detected as a halftone dot.

  Therefore, the present invention provides an image processing apparatus, an image forming apparatus, an image processing method, a program, and a recording medium capable of accurately determining a character as a character even if the character included in the image data is small in size. The purpose is to provide.

  In order to solve the above problems, an image processing apparatus according to an aspect of the present invention includes a frequency conversion unit that converts image data into a spatial frequency component, a frequency analysis unit that obtains the intensity of the spatial frequency component, and the spatial Of the intensities of the frequency components, the intensities of the high frequency components belonging to the relatively high frequencies are compared with a predetermined threshold, and the intensity of the high frequency components is greater than the predetermined threshold. While the character size included is determined to be a relatively large size, the character size included in the image data is determined to be a relatively small size when the intensity of the high frequency component is equal to or less than the predetermined threshold. And a determination unit.

  According to one embodiment of the present invention, even if a character included in image data has a small size, the character can be accurately determined as a character.

1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the character size determination part shown in FIG. It is a flowchart which shows the character size determination operation | movement by the character size determination part shown in FIG. FIG. 4 is a flowchart illustrating a character size determination operation performed by a character size determination unit following FIG. 3. It is a flowchart which shows operation | movement of the diagonal direction determination part shown in FIG. 3 is a flowchart illustrating operations of a density determination unit and an adjacent pixel determination unit illustrated in FIG. 2. It is a block diagram which shows the structure of the image forming apparatus of 2nd Embodiment of this invention.

<First Embodiment>
A first embodiment of the present invention will be described below with reference to the drawings.

(Outline of image forming apparatus 100)
FIG. 1 is a block diagram showing a configuration of an image forming apparatus 100 according to the first embodiment of the present invention.

  As shown in FIG. 1, an image forming apparatus (for example, a digital color copying machine) 100 includes a color image input apparatus 1, a color image processing apparatus (image processing apparatus) 2, a color image output apparatus (image forming unit) 3, and various types. An operation panel 4 for performing an operation and a control unit 7 for controlling the above-described units are provided.

  In the image forming apparatus 100, RGB (R: red, G: green, B: blue) analog signal image data obtained by reading a document with the color image input apparatus 1 is output to the color image processing apparatus 2. The color image processing device 2 performs predetermined processing and outputs the digital color signal of CMYK (C: cyan, M: magenta, Y: yellow, K: black) to the color image output device 3.

  The color image input device 1 is, for example, a scanner including a CCD (Charged Coupled Device), irradiates light on a document, and reads a reflected light image from the document image as RGB analog signals. Further, the read RGB signal is output to the color image processing apparatus 2.

  The color image output device 3 outputs an image of a document on recording paper based on the document image data processed by the color image processing device 2. The color image output device 3 is a printer such as an electrophotographic system or an inkjet system. The color image output device 3 may be a display device such as a display.

(Outline of color image processing device 2)
The color image processing apparatus 2 includes an A / D conversion unit 20, a shading correction unit 21, an input tone correction unit 22, a region separation processing unit 23, a color correction unit 24, a black generation and under color removal unit 25, and a spatial filter processing unit 26. A zoom unit 27, an output tone correction unit 28, a tone reproduction processing unit 29, and a character size determination unit 30. The operation of each part is controlled by the control unit 7. The control unit 7 includes a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or the like, and is configured by an ASIC (Application Specific Integrated Circuit) or the like.

(A / D converter 20)
The A / D (analog / digital) converter 20 converts the RGB signal input from the color image input device 1 into, for example, a 10-bit digital signal, and outputs the converted RGB signal to the shading correction unit 21. .

(Shading correction unit 21)
The shading correction unit 21 performs a correction process to remove various distortions generated in the illumination system, the imaging system, and the imaging system of the color image input apparatus 1 on the input RGB signal, and the corrected RGB signal is converted into the corrected RGB signal. Output to the input tone correction unit 22.

(Input tone correction unit 22)
The input tone correction unit 22 is an image processing system employed in the color image processing apparatus 2 such as a density signal for the RGB signal (RGB reflectance signal) from which various distortions have been removed by the shading correction unit 21. It is converted into an easy-to-handle signal. Further, the converted RGB signal is subjected to color balance adjustment processing and image quality adjustment processing such as background density removal or contrast, and the processed RGB signal is sent to the region separation processing unit 23 and the character size determination unit 30. Output.

(Area separation processing unit 23)
Based on the input RGB signal, the region separation processing unit 23 determines whether each pixel in the input image belongs to, for example, a character region, a dot region, a photo region, or other regions, The pixel is separated into one of the above regions. In addition, the region separation processing unit 23 outputs a region identification signal indicating which region each pixel belongs to based on the separation result of each image, as a color correction unit 24, a black generation and under color removal unit 25, and a spatial filter processing unit. 26 and the gradation reproduction processing unit 29. The region separation processing unit 23 outputs the input RGB signal as it is to the subsequent color correction unit 24.

(Character size determination unit 30)
The character size determination unit 30 determines the presence / absence of characters and the character size in the document image (image data) from the RGB signals input from the input tone correction unit 22. When the character size determination unit 30 determines the character size, the character size determination signal indicating the determination result is sent to the color correction unit 24, the black generation and under color removal unit 25, the spatial filter processing unit 26, and the gradation reproduction processing unit 29. Output. It should be noted that the character size is determined in at least two levels, which are necessary for properly using the filtering process according to the character size in the spatial filter processing unit 26.

  The character size determination unit 30 may further perform filter processing. In this filter processing, when it is determined that a character exists and the character size is determined, enhancement or smoothing processing according to the character size is performed. If it is determined that there is no character, the RGB signal is output as it is to the next process without performing the filter process. Further, the filtering process may be performed not by the character size determination unit 30 but by the subsequent spatial filter processing unit 26. Details of the character size determination unit 30 will be described later.

(Color correction unit 24)
The color correction unit 24 converts the RGB signal input from the region separation processing unit 23 into a CMY color space according to each region indicated by the region identification signal input from the region separation processing unit 23. The converted signal is subjected to color correction in accordance with the characteristics of the color image output device 3, and the corrected CMY signal is output to the black generation and under color removal unit 25. Specifically, the color correction unit 24 performs a process of removing color turbidity based on the spectral characteristics of CMY color materials including unnecessary absorption components in order to make color reproduction faithful.

(Black generation under color removal unit 25)
The black generation and under color removal unit 25 generates a K (black) signal based on the CMY signal input from the color correction unit 24 in accordance with each region indicated by the region identification signal input from the region separation processing unit 23. The black generation process is performed. Further, under color removal processing is performed to generate a new CMY signal by subtracting the K signal from the input CMY signal, and the generated CMYK signal is output to the spatial filter processing unit 26.

  An example of the black generation process in the black generation and under color removal unit 25 is shown below. For example, in the process of generating black by skeleton black (general method), the input / output characteristic of the skeleton curve is y = f (x), the input data is C, M, Y, and the output data Is C ′, M ′, Y ′, K ′, and the UCR (Under Color Removal) rate is α (0 <α <1), the data output by the black generation and under color removal processing is K ′. = F {min (C, M, Y)}, C ′ = C−αK ′, M ′ = M−αK ′, and Y ′ = Y−αK ′.

(Spatial filter processing unit 26)
The spatial filter processing unit 26 applies a digital filter to the CMYK signal that has been subjected to black generation processing by the black generation and under color removal unit 25 according to each region indicated by the region identification signal input from the region separation processing unit 23. Spatial filter processing is performed using (filter coefficient set). Thereby, the spatial frequency characteristics of the image data are corrected, and blurring of the output image in the color image output device 3 or deterioration of graininess is prevented. The spatial filter processing unit 26 outputs the filtered image data (CMYK signal) to the scaling unit 27.

(Variation 27)
The scaling unit 27 performs an enlargement process or a reduction process (magnification process) on the CMYK signal input from the spatial filter processing unit 26 based on the scaling factor designated by the user via the operation panel 4. The scaling process performed on the image data (CMYK signal) is performed by interpolating pixel data (in the case of increasing the resolution) or thinning out (in the case of decreasing the resolution) in the main scanning direction and the sub-scanning direction. It is realized by doing. Further, the scaling process may be optically performed in the sub-scanning direction, and the scaling process by interpolation may be performed in the main scanning direction.

  In the present embodiment, the scaling factor is not limited to the scaling factor input (designated) by the user via the operation panel 4 when the image data is enlarged or reduced and output. For example, when the original image is read by changing the reading speed by the color image input device 1 (faster or slower), converted to the same size image data (the image magnification is 100%), and output to the color image output device 3 In addition, the scaling factor in the interpolation processing performed on the image data in the sub-scanning direction is also included.

  For example, when the standard reading resolution by the color image input device 1 is 600 dpi (dot per inch) (600 dpi × 600 dpi), when the reading speed by the color image input device 1 is increased (600 dpi × 300 dpi), the image to be read Data is reduced to 50%. When the reduced image data is converted into equal-size image data and output to the color image output device 3, the scaling unit 27 performs conversion processing (interpolation processing) into equal-size (100%) image data. Done.

  As the interpolation processing, a nearest neighbor method, a bilinear method, a bicubic method, or the like can be used. The nearest neighbor method is a method in which a pixel value of an existing pixel closest to a pixel to be interpolated (interpolated pixel) or a pixel value of an existing pixel having a predetermined positional relationship with respect to the interpolated pixel is used as the pixel value of the interpolated pixel. is there. The bilinear method is a method in which the pixel values of four existing pixels surrounding the interpolation pixel are weighted with values proportional to the distance from the interpolation pixel, and the average value of the obtained values is used as the pixel value of the interpolation pixel. In the bicubic method, a value calculated based on pixel values of a total of 16 existing pixels obtained by adding 12 existing pixels surrounding them to 4 existing pixels surrounding the interpolation pixel is used as the pixel value of the interpolation pixel. Is the method.

  In the above description, the processing of the scaling unit 27 is performed after the processing of the spatial filter processing unit 26. However, the processing of the scaling unit 27 may be performed before the processing of the spatial filter processing unit 26.

(Output tone correction unit 28)
The output tone correction unit 28 performs output tone correction processing for converting the CMYK signal (density signal) input from the spatial filter processing unit 26 into a halftone dot area ratio that is a characteristic value of the color image output device 3. And output the CMYK signal after the output tone correction processing to the tone reproduction processing unit 29.

(Tone reproduction processing unit 29)
The gradation reproduction processing unit 29 performs predetermined processing on the CMYK signal input from the output gradation correction unit 28 based on each region indicated by the region identification signal input from the region separation processing unit 23. The tone reproduction processing unit 29 is a high-resolution screen suitable for reproducing high-frequency components in the color image output device 3 in order to improve the reproducibility of black characters or color characters, for example, in an area separated into character areas. A binarization process or a multi-value process is performed.

  Further, the gradation reproduction processing unit 29 finally separates the image into pixels for the region separated into the halftone dot regions in the region separation processing unit 23, and reproduces the respective gradations. Performs reproduction processing (halftone generation). Further, the gradation reproduction processing unit 29 performs binarization processing or multi-value processing on the screen with an emphasis on gradation reproducibility in the color image output apparatus 3 for the region separated into the photographic region by the region separation processing unit 23. Process.

  The color image processing apparatus 2 temporarily stores the image data (CMYK signal) processed by the gradation reproduction processing unit 29 in a storage unit (not shown), and stores the image data at a predetermined timing for image formation. The read image data is output to the color image output device 3. These controls are performed by the control unit 7.

(Operation panel 4)
The operation panel 4 includes, for example, a display unit such as a liquid crystal display and setting buttons. The control unit 7 controls operations of the color image input device 1, the color image processing device 2, and the color image output device 3 based on information input from the operation panel 4.

(Details of character size determination unit 30)
Next, the configuration of the character size determination unit 30 will be described in detail. FIG. 2 is a block diagram illustrating a configuration of the character size determination unit 30.

  As shown in FIG. 2, the character size determination unit 30 includes a storage unit 300, a pixel value reading unit (division processing unit) 301, a frequency conversion unit 302, a frequency analysis unit 303, a determination unit 304, and a correction unit 305. . The correction unit 305 includes a density determination unit 306, an adjacent pixel correction unit 307, a diagonal direction determination unit 308, and a mask processing unit 309. Further, the mask processing unit 309 includes a frequency-specific intensity correction unit (frequency component adjustment unit) 310, a frequency inverse conversion unit 311, and an output determination unit 312.

(Pixel value reading unit 301)
The pixel value reading unit 301 reads the designated number of pixels in the main scanning direction and the sub-scanning direction from the image data as one block pixel, reads the density values of these pixels, and stores them in the storage unit 300. The number of pixels in one block is arbitrary, but is preferably a power of 2. Further, if the number of pixels in one block is too large, it takes a lot of time for calculation. Therefore, it is preferably 8 to 16 in both the main scanning direction and the sub-scanning direction. Note that the pixel data stored in the storage unit 300 is deleted when the processing proceeds to the processing after the frequency conversion unit 302 and the correction unit 305.

  The reading process is performed for each color component, and is performed by sequentially reading each block set in the image data as described above. The order of reading each block is not particularly limited. Normally, the blocks arranged in the main scanning direction are sequentially read from the end block to the end block, and then this reading operation is sequentially performed from the end block to the end block in the sub-scanning direction. Further, as to whether to read from the left or right of the blocks arranged in the main scanning direction, any line may be read from the left or right. For example, the first line may be read zigzag from the left and the second line from the right.

(Frequency converter 302)
The frequency conversion unit 302 converts the image data into a spatial frequency component by performing discrete Fourier transform in the main scanning direction and the sub-scanning direction for each color component for the pixel values belonging to each of the blocks. The operation of the discrete Fourier transform is theoretically performed by the equation (1). Here, f is a value after the discrete Fourier transform, u and v are frequencies in the main scanning direction and the sub scanning direction, m and s are block positions in the main scanning direction and the sub scanning direction, and M , S is the number of pixels in the main scanning direction and sub-scanning direction of the block.

f (u, v, m, s, c) = αl * Σp (x, y, m, s) * exp (−2πi * u * x / M) * exp (−2πi * v * y / S) (1)
In equation (1), p (x, y, m, s) is the pixel value of the pixel at the position of the coordinate (x, y) in the XY coordinate system of the component c of the block B (m, s). is there. M and S are the number of pixels in the X-axis direction and Y-axis direction of the block. f (u, v, m, s, c) is a value obtained by Fourier transforming p (x, y, m, s), and is generally a complex number for each frequency and color component in the main scanning direction and sub-scanning direction. Takes the value of u and v are frequencies in the X-axis direction and the Y-axis direction. αl is a scaling coefficient, and for example, 1 or 1 / (M * S) is used. Note that equation (1) is theoretical, and in fact, a fast Fourier transform (FFT) algorithm can be applied to increase the processing speed.

  Next, the absolute value F of f is calculated using Expression (2).

F (u, v, m, s, c) = | f (u, v, m, s, c) | (2)
However, in an actual circuit, the real part is converted by the Cos function and the imaginary part by the Sin function instead of the Exp function. Cos and Sin take the form of equations (3) and (4) according to the block size.

Ref (u, v, m, s, c) = αl * Σp (x, y, m, s, c) * [cos (-2π * u * x / M) * cos (-2π * v * y / S) −sin (−2π * u * x / M) * sin (−2π * v * y / S)] (3)
Imf (u, v, m, s, c) = αl * Σp (x, y, m, s, c) * [sin (-2π * u * x / M) * cos (-2π * v * y / S) + cos (-2π * u * x / M) * sin (-2π * v * y / S)] (4)
Further, F is calculated using equation (5).

  F (u, v, m, s, c) = (Ref (u, v, m, s, c) ^ 2 + Imf (u, v, m, s, c) ^ 2) ^ 0.5 (5 These numerical values are erased from the storage unit 300 after the processing is completed and the calculated f or F is stored in the storage unit 300. In addition to discrete Fourier transform, discrete cosine transform or discrete sine transform may be used.

(Frequency analysis unit 303)
For each block in which pixels are converted to a frequency by the frequency conversion unit 302, the frequency analysis unit 303 performs predetermined frequency (excluding the DC component) in a specific direction (for example, main scanning direction or sub-scanning direction). It is divided into a plurality of categories such as a low band and a high band, or a low band, a middle band and a high band according to a threshold value. Further, the characteristics are extracted by analyzing the frequency for each section.

  Specifically, in each section, select the frequency with the highest intensity, extract the intensity of a specific frequency, or further divide the frequency into several sections and select the section with the highest sum of intensity. Such processing is performed. Regarding the direction, the above-described analysis is performed at least in the main scanning direction and the sub-scanning direction. For the color component, the same analysis is performed for each color component. Alternatively, the analysis is performed by using the sum of the analysis results for all the color components. The above analysis results are stored in the storage unit 300.

(Determination unit 304)
The determination unit 304 determines the analysis result of the frequency analysis unit 303 related to the intensity called from the storage unit 300 for each frequency (frequency division), for each direction (for example, the main scanning direction and the sub-scanning direction), and for each color component. The character size is determined for each block based on the comparison result based on the comparison result. At this time, the determination result of the character size for each pixel follows the determination result in the block to which the pixel belongs. The direction used for the determination may be limited to only the main scanning direction and the sub-scanning direction. The determination result is stored in the storage unit 300.

(Correction unit 305)
The correction unit 305 determines the character size for each pixel based on the character size determined by the determination unit 304. For this purpose, the correction unit 305 includes a density determination unit 306, an adjacent pixel correction unit 307, a diagonal direction determination unit 308, and a mask processing unit 309. Further, the mask processing unit 309 includes a frequency-specific intensity correction unit 310, a frequency inverse conversion unit 311, and an output determination unit 312. Details of the processing in the correction unit 305 will be described below.

(Density determination unit 306)
The density determination unit 306 calculates and stores the total density value, standard deviation, or difference between the maximum value and the minimum value for each row and column of the image data input to the character size determination unit 30. Next, the total value, the standard deviation or the difference between the maximum value and the minimum value is compared with a predetermined threshold value, and the determination result in the determination unit 304 for the pixel belonging to the column or row is corrected according to the result. . The correction result is stored in the storage unit 300. For example, if the difference between the maximum value and the minimum value is less than or equal to the threshold value, the character size of the pixel belonging to the row or column is determined to be 0, that is, no character. Note that the correction method of the determination result in the determination unit 304 is not limited to this.

(Adjacent pixel correction unit 307)
The adjacent pixel correction unit 307 sets a target pixel for the determined pixel stored in the storage unit 300, that is, the pixel determined by the determination unit 304 and corrected by the density determination unit 306. The determination result of the target pixel is corrected by comparing the determination result of the adjacent pixel and the determination result of the target pixel. For example, if the character size of the pixel of interest is large and the character size of the adjacent pixel is small, the character size of the pixel of interest is rewritten to be large. Note that the determination result correction method is not limited to this.

(Diagonal direction determination unit 308)
The diagonal direction determination unit 308 calculates the intensity or the sum of the intensity in a band where the frequency is higher than a predetermined threshold (frequency) in the main scanning direction and the sub-scanning direction of each block. Next, by comparing the calculated intensity value with a predetermined threshold value, it is determined whether each block is a character or a point other than a character. When it is determined that the block is a point other than the character, the determination result in the determination unit 304 is corrected.

(Mask processing unit 309)
The frequency-specific intensity correction unit 310 amplifies and reduces the intensity at a predetermined magnification based on the character size determination result of the determination unit 304 for the spatial frequency component acquired from the frequency conversion unit 302. For the above magnification, the numerical values specified for each of the high frequency range and low frequency set by the frequency converter 302 are used. As a result, a large-size character is processed to make the character easy to see by making the sentence thick, and a small-size character is processed so that the amplitude of the line is amplified to make the thin line appear dark.

  The frequency inverse transform unit 311 performs inverse discrete Fourier transform or the like on the frequency characteristic after the intensity is corrected by the frequency-specific intensity correction unit 310, and returns the image data to the pixel value distribution form.

  The output determination unit 312 determines whether to output the pixel data corrected by the correction unit 305 or the image data not corrected by the correction unit 305 as the output of the character size determination unit 30, One of the image data is output based on the determination. Note that the above-described determination of the output image data in the output determination unit 312 is performed, for example, by user selection.

  Each threshold used in the above processing is a value that can be arbitrarily designated by the manufacturer or user of the image forming apparatus 100. Note that the character size determination in the character size determination unit 30 uses a value that considers the frequency of use of characters for each character type as a threshold value, so that the number of characters to be used is limited to kanji, particularly alphabets and kana. By using the character type, it is possible to determine with high accuracy.

  In the above configuration, the operation of the character size determination unit 30 will be described below. First, an example of the concept of character size determination in the character size determination unit 30 will be briefly described.

  The lines constituting the characters generally tend to have more vertical and horizontal lines than diagonal lines. This tendency is particularly remarkable in kanji. Therefore, in determining characters based on the frequency characteristics, characteristics in the main scanning direction and the sub-scanning direction can be used. Also, for kana and alphabet, the number of vertical and horizontal lines is not as many as kanji. Therefore, kana and alphabets can be handled as characters having fewer lines than kanji in frequency characteristics.

  Further, the relationship between the character size and the frequency characteristic is roughly divided into two cases depending on the size of the character.

  When the character size is large, a block including a predetermined number of pixels in the main scanning direction and the sub-scanning direction often includes only one line, and rarely includes two or more lines. Moreover, since the line which comprises a character has the thickness for several pixels, the area which occupies for the said block is large. In such a case, the first intensity peak after Fourier transform is the largest, and the second and subsequent peaks tend to be considerably smaller than the first.

  On the other hand, when the character size is small, there are often cases where a plurality of lines are included in each block, and the lines often occupy half the number of pixels constituting one side of the block. In such a case, when the number of lines is large, the intensity peak after Fourier transformation is the largest for the number of lines.

  Even when the character size is small, there are many cases where only one line is included in each block. In such a case, the line constituting the character is only about one pixel thick, and the area of the line occupying the block is small. Therefore, in such a case, the intensity difference between the first and the second and subsequent lines is smaller than when the character size is large and the line is thick.

  In any case, the high frequency component becomes larger when the character size is larger. Therefore, after Fourier transform, for example, if the frequency is divided into a high frequency range and a low frequency range at the half of the Nyquist frequency, the strongest component is selected in each category, and the intensity ratio of those components is calculated. The character size can be obtained based on the calculation result.

  Next, the operation of the character size determination unit 30 will be described with reference to FIGS. FIG. 3 is a flowchart showing the character size determination operation by the character size determination unit 30. FIG. 4 is a flowchart illustrating the character size determination operation performed by the character size determination unit 30 following FIG. 3 and 4 are performed by the storage unit 300, the pixel value reading unit 301, the frequency conversion unit 302, the frequency analysis unit 303, and the determination unit 304 of the character size determination unit 30 illustrated in FIG. It is.

  The character size determination unit 30 acquires image data (S1), and divides the acquired image data into a plurality of blocks having a predetermined size (S2). Next, the following processing is sequentially performed for each block, and when the processing for all the blocks is completed (S3), the processing ends.

  If the processing for all the blocks is not completed in S3, frequency conversion is performed for each color component for the values of the pixels belonging to each block (S4).

  Next, each frequency region in the main scanning direction and the sub-scanning direction is divided into two sections by a first threshold value (one threshold value). That is, the frequency region in the main scanning direction is divided into a high frequency region and a low frequency region, and the sub scanning frequency region is divided into a high frequency region and a low frequency region (S5).

  Next, the maximum intensity is calculated for each of the high-frequency and low-frequency divisions in the main scanning direction and the high-frequency and low-frequency divisions in the sub-scanning direction (S6). ).

  Next, the intensity of the DC component in the main scanning direction or the sub-scanning direction is compared with a second threshold value (one threshold value) (S7). As a result of the comparison in S7, if the intensity of the DC component is larger than the second threshold value (S8), the maximum value of the high frequency division in the main scanning direction and the sub-scanning direction is set to the third threshold value (one threshold value). (S9).

  As a result of the comparison in S9, if the maximum value of the high frequency segment is larger than the third threshold (S10), it is determined that the character size is small (S11). Here, as the determination result that the character size is small, the first determination result when the maximum value of the high frequency division in the main scanning direction is larger than the third threshold, and the high frequency in the sub scanning direction A second determination result is obtained when the maximum value of the frequency category is larger than the third threshold value.

  On the other hand, in S10, if the maximum value of the high-frequency classification is equal to or smaller than the third threshold value, it is determined that the character size is large (S12). Here, as the determination result that the character size is large, the third determination result when the maximum value of the high frequency range in the main scanning direction is equal to or smaller than the third threshold, and the high frequency in the sub scanning direction A fourth determination result is obtained when the maximum value of the frequency division is equal to or less than the third threshold value.

  In the determination of S8, if the intensity of the DC component is equal to or less than the second threshold value, the maximum intensity of the high frequency section and the intensity of the low frequency section for each of the main scanning direction and the sub-scanning direction. A ratio with the maximum value (hereinafter referred to as the maximum intensity ratio) is obtained (S13). Then, the obtained maximum intensity ratio is compared with the fourth threshold value (S14).

  As a result of the comparison in S14, if the maximum intensity ratio is larger than the fourth threshold (S15), it is determined that the character size is small (S16). Here, as the determination result that the character size is small, the fifth determination result when the maximum intensity ratio in the main scanning direction is larger than the fourth threshold, and the maximum intensity ratio in the sub-scanning direction are the fourth. A sixth determination result in the case of being larger than the threshold value is obtained.

  On the other hand, if the maximum intensity ratio is equal to or smaller than the fourth threshold in S15, it is determined that the character size is large (S17). Here, as a determination result that the character size is large, the seventh determination result when the maximum intensity ratio in the main scanning direction is equal to or smaller than the fourth threshold value, and the maximum intensity ratio in the sub-scanning direction are the fourth. An eighth determination result in the case of being equal to or less than the threshold value is obtained. Note that the first to eighth determination results include determination results for each color component.

  Finally, the character size is determined to be either large or small based on the first to eighth determination results for each color component (S18). In this case, the character size is determined by referring to the determination results in S10 and S15 in the main scanning direction and S10 and S15 in the sub-scanning direction. If the character size is determined, the character size is reduced.

  In the above description, the character size is two levels, large and small, but the character size may be three or more. For example, when the character size is set to three levels of large, medium and small, it can be dealt with by increasing the character size determination threshold by one.

  Next, the operation of the correction unit 305 of the character size determination unit 30 will be described. FIG. 5 is a flowchart showing the operation of the diagonal direction determination unit 308 shown in FIG. FIG. 6 is a flowchart illustrating operations of the density determination unit 306 and the adjacent pixel correction unit 307 illustrated in FIG.

  The correction unit 305 corrects the character size determination result in the determination unit 304. In this case, as shown in FIG. 5, the diagonal direction determination unit 308 obtains the result of frequency conversion of each block performed by the frequency conversion unit 302, and the intensity of the frequency component in the diagonal direction for each block. Is calculated (S31). In this process, when the block is a rectangular region including a plurality of pixels, for example, the sum of the frequency component intensities of the pixels on the diagonal of the rectangle is calculated.

  Next, the sum of the intensities of the diagonal frequency components calculated in S31 is compared with a fifth threshold value (S32). If the sum is larger than the fifth threshold value as a result of this comparison (S33), the character size determination result of the block is set to 0 (S34).

  In addition to the above processing, as shown in FIG. 6, the density determination unit 306 performs, for each block of image data, the sum of pixel values (density values) of rows, the standard deviation, or the difference between the maximum value and the minimum value. Then, the sum, standard deviation, or difference between the maximum value and the minimum value of the pixel values (density values) of the column is calculated (S41). In this process, for example, the difference between the maximum and minimum pixel values is calculated for each row included in the block, and the difference between the maximum and minimum pixel values is calculated for each column.

  Next, the difference between the maximum value and the minimum value of the pixel values in the calculated row and the difference between the maximum value and the minimum value in the column are compared with the sixth threshold value (S42). Note that the sixth threshold value may be different for rows and columns. As a result of the comparison in S42, the pixels belonging to the row where the difference between the maximum value and the minimum value of the pixel values is smaller than the sixth threshold value, and the column where the difference between the maximum value and the minimum value of the pixel values is smaller than the sixth threshold value. For the pixels belonging to (S43), the character size determination result is set to 0 (S44).

  The determination result of the character size for each pixel is obtained by the processing of the density determination unit 306 described above. Next, this determination result is further corrected by the adjacent pixel correction unit 307. In this case, the adjacent pixel correction unit 307 compares the determination result of the pixels in the predetermined range around the target pixel with the determination result of the target pixel, and determines the target pixel determination result based on the comparison result. Is corrected (S45). This correction is performed, for example, when there are a predetermined number or more of pixels with a small character size or no character around a pixel with a large character size, or with a large character size or no character around a pixel with a small character size. When there are a predetermined number of pixels or more, the determination of the character size is rewritten to the surrounding determination result.

  With the above processing, the character size can be determined for each pixel of the image data. The character size determination result obtained in this way can be used for filter switching (selection) in the spatial filter processing unit 26 in combination with the region separation result in the region separation processing unit 23.

  That is, the spatial filter processing unit 26 performs filter processing according to the character size. When the character size is small, an emphasis filter is used to increase the amplitude of the high frequency. On the other hand, when the character size is large, a smoothing filter can be selected to thicken the character line. However, according to the user's desire, it is possible to select a filter similar to the case of a small character size, and it is also possible to select a filter different from them.

  The character size determination result in block units can be used for switching the setting of JPEF compression.

  A compression unit (not shown) included in the color image output device 6 can switch the compression setting depending on the presence / absence of characters and the character size. For example, in an area where no character exists, the image data storage efficiency and transmission efficiency can be improved by setting a higher compression ratio than usual. On the other hand, in a region where characters are present, character image quality can be maintained or improved by reducing the compression rate in accordance with the character size.

  Further, the frequency-specific intensity correction unit 310 of the mask processing unit 309 performs the character for each block determined by the determination unit 304 or the diagonal direction determination unit 308 with respect to the intensity distribution of the frequency component converted by the frequency conversion unit 302. Perform correction according to the size. The frequency reverse conversion unit 311 performs reverse conversion on the data processed by the frequency-specific intensity correction unit 310.

  Thereby, the image data obtained by performing the inverse transform in the frequency inverse transform unit 311 can be used for the subsequent image processing. For example, by performing processing such as weakening the high-frequency component for blocks that are determined to have a large character size and weakening the low-frequency component for blocks that are determined to have a small character size, the subsequent filter processing can be facilitated. Can be.

  The image forming apparatus 100 and the image forming apparatus 101 to be described later are not limited to digital color copiers, and have one or more of a copy function, a printer function, a facsimile transmission / reception function, and a scan to e-mail function. It may be a digital color multifunction machine provided. The digital color multi-function peripheral can further include a communication device such as a modem or a network card. In this case, for example, when transmitting a facsimile, if the modem performs a transmission procedure with the other party and secures a state in which transmission is possible, image data compressed in a predetermined format (image read by a scanner) Data) is read from the memory, subjected to necessary processing such as changing the compression format, and sequentially transmitted to the other party via a communication line.

  When receiving a facsimile, the image data transmitted from the other party is received and output to the color image processing apparatus 2 while performing a communication procedure. The color image processing apparatus 2 compresses / decompresses the received image data. A decompression process is performed by a processing unit (not shown). The decompressed image data is subjected to rotation processing and resolution conversion processing as necessary, subjected to output tone correction and tone reproduction processing, and is output from the color image output device 3.

  Further, the image forming apparatuses 100 and 101 may be configured to perform data communication with a computer and other digital multi-function peripherals connected to the network via a network card, a LAN cable, or the like. Further, the present invention can be applied not only to a color multifunction peripheral but also to a multifunction peripheral that handles monochrome images and a facsimile communication apparatus that has only a facsimile communication function.

  In each embodiment, for example, a flat bed scanner, a film scanner, a digital camera, or a mobile phone is used as the color image input device 1. Instead of acquiring the color image data from the color image input device 1, the color image data may be acquired from an external storage device or a server device via a network. Further, as the color image output device 3, for example, an image display device such as a CRT display or a liquid crystal display, or an electrophotographic or ink jet printer that outputs processing results to recording paper or the like is used.

Second Embodiment
A second embodiment of the present invention will be described below with reference to the drawings.
FIG. 7 is a block diagram showing the configuration of the image forming apparatus 101 according to the second embodiment of the present invention. An image forming apparatus (for example, a digital color copying machine) 101 includes a color image input apparatus 1, a color image processing apparatus (image processing apparatus) 5, a color image output apparatus 6 as image forming means, and an operation panel 4.

  The basic configuration of the color image processing apparatus 5 is almost the same as that of the color image processing apparatus 2. However, the color image processing apparatus 5 is different from the color image processing apparatus 2 in that the black generation and under color removal unit 25 does not exist and that RGB signals also flow after the color correction unit 24. The color image output apparatus 6 includes an image compression processing unit (image data processing unit) 41 that performs a known image compression process. Here, as an example, JPEG compression processing performed by the image compression processing unit 41 will be described.

  For JPEG compression processing, an encoding method combining orthogonal image encoding and variable length encoding has been conventionally used. In JPEG compression processing, each pixel value of image data is converted into a luminance component and a color difference component by color component conversion based on the image data encoding method.

  Next, the luminance component and the color difference component are divided and processed so as to correspond to a predetermined size block. A block is, for example, 8 pixels × 8 pixels for luminance. The image compression processing unit 41 performs two-dimensional DCT (Discrete Cosine Translation) as orthogonal transform in the order of zigzag scanning for each divided block. As a result, the image data is converted into a DC component and an AC component, which are frequency conversions. The image compression processing unit 41 performs division by the quantization width for each frequency component for which frequency components are set. Thereby, linear quantization according to each frequency component is performed. Next, variable length coding is performed by Huffman coding according to the value after quantization to generate encoded data.

  The size of the encoded data becomes smaller as the frequency component that becomes zero by linear quantization increases. Thereby, data transmission efficiency and storage efficiency are improved. In addition, when the encoded data is decoded and restored to image data composed of pixel values, the encoded data is subjected to processing opposite to the encoding. In this case, the frequency component that has become zero by linear quantization and the fraction rounded off during other operations are not completely restored. For this reason, noise such as mosquito noise or block noise occurs in the image after decoding the encoded data, and the image quality deteriorates. As described above, the data transmission efficiency and the storage efficiency and the image quality of the image decoded after encoding, that is, the degree of occurrence of the mosquito noise or block noise described above vary depending on the frequency characteristics of the image.

<Third Embodiment>
The color image processing apparatuses 2 and 5 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  In other words, the color image processing apparatuses 2 and 5 include a CPU (Central Processing Unit) that executes instructions of a control program for realizing each function, a ROM (read only memory) that stores a computer program, and a RAM that develops various control programs. (Random access memory), various control programs, and a storage device (recording medium) such as a memory for storing various data.

  An object of the present invention is a computer-readable recording in which program code (execution format program, intermediate code program, source program) of a program that performs filter coefficient synthesis processing, which is software that realizes the above-described functions, is recorded. This can also be achieved by supplying the medium to the color image processing apparatuses 2 and 5 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU). As a result, it is possible to provide a portable recording medium on which a computer program code for controlling the filter coefficient synthesis process is recorded.

  The recording medium may be a non-illustrated memory, for example, a program medium such as a ROM because processing is performed by a microcomputer, and a program reading device as an external storage device (not illustrated) is provided, and the recording medium is stored therein. It may be a program medium that can be read by being inserted.

  In any case, the stored computer program code may be configured to be accessed and executed by the microprocessor, or the computer program code is read and the read computer program code is shown in the figure of the microcomputer. The computer program code may be downloaded to a program storage area that is not yet executed, and the computer program code may be executed. In this case, it is assumed that the computer program for download is stored in the main device in advance.

  Here, the program medium is a recording medium configured to be separable from the main body, and includes a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a flexible disk and a hard disk, and a CD-ROM / MO / MD / DVD / Disk systems including optical disks such as CD-R, card systems such as IC cards (including memory cards) / optical cards, mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), registration Trademark), a medium that carries a computer program fixedly, including a semiconductor memory such as a flash ROM.

  Further, the color image processing apparatuses 2 and 5 may be configured to be connectable to a communication network, and may be a medium that fluidly carries computer program code so that the program code is downloaded via the communication network. When the computer program code is downloaded from the communication network in this way, the computer program for downloading may be stored in the main device in advance or installed from another recording medium. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite A communication network or the like is available.

  Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

[Summary]
The image processing apparatus according to the first aspect of the present invention includes a frequency conversion unit 302 that converts image data into a spatial frequency component, a frequency analysis unit 303 that obtains the intensity of the spatial frequency component, and the intensity of the spatial frequency component. The intensity of the high frequency component belonging to the relatively high frequency is compared with a predetermined threshold, and when the intensity of the high frequency component is larger than the predetermined threshold, the character size included in the image data is relative A determination unit 304 that determines that the character size included in the image data is a relatively large size when the intensity of the high-frequency component is equal to or less than the predetermined threshold. Yes.

  According to the above configuration, the frequency conversion unit 302 converts the image data into a spatial frequency component, and the frequency analysis unit 303 obtains the intensity of the spatial frequency component. The determination unit 304 compares the intensity of the high frequency component belonging to the relatively high frequency out of the intensity of the spatial frequency component with a predetermined threshold, and when the intensity of the high frequency component is larger than the predetermined threshold, While the character size included in the image data is determined to be relatively small, the character size included in the image data is determined to be relatively large when the intensity of the high frequency component is equal to or less than a predetermined threshold. .

  Thereby, even if the character contained in image data is a small size, the character can be correctly determined as a character.

  Therefore, based on the character size determination result, it is possible to switch processing such as a filter for a character and a compression rate for each character size. For example, processing for increasing the resolution of small characters, amplifying the line amplitude to make thin lines appear darker, or reducing the compression rate, and increasing the compression rate for large characters. It is possible to perform processing such as raising the compression rate slightly, and further processing such as increasing the compression rate when there is no character. As a result, it is possible to make the characters easier to see at each size, and the image quality of the output image can be improved.

  In the image processing apparatus according to aspect 2 of the present invention, in the above aspect 1, the determination unit 304 determines a character size for each of the main scanning direction and the sub-scanning direction of the high-frequency component, and based on the determination results. The character size may be determined.

  According to the above configuration, the determination unit 304 determines the character size for each of the high-frequency component in the main scanning direction and the sub-scanning direction, and determines the character size based on the determination result. The character size to be determined can be accurately determined.

  The image processing apparatus according to aspect 3 of the present invention includes the division processing unit (pixel value reading unit 301) in the preceding stage of the frequency conversion unit 302 in the above aspect 1 or 2, and the division processing unit stores a plurality of pieces of image data. Each block includes a plurality of pixels in the main scanning direction and the sub-scanning direction, and the determination unit 304 determines a character size for each block, and determines a character size for each block. The character size of the image data may be determined based on the result.

  According to the above configuration, the division processing unit (pixel value reading unit 301) divides the image data into a plurality of blocks, and each of the blocks includes a plurality of pixels in the main scanning direction and the sub-scanning direction. 304 determines the character size for each block, and determines the character size of the image data based on the determination result of the character size for each block. Accordingly, the determination unit 304 can easily and accurately determine the character size.

  The image processing apparatus according to aspect 4 of the present invention is the image processing apparatus according to any one of aspects 1 to 3, based on a character size determination result in the determination unit 304 for the spatial frequency component acquired from the frequency conversion unit 302. A frequency component adjustment unit (intensity correction unit 310 for each frequency) that performs amplification or reduction of intensity, and a frequency inverse unit that inversely converts the spatial frequency component processed by the frequency component adjustment unit into image data of a pixel value and outputs it. It is good also as a structure provided with the conversion part 311 and the image data process part which processes the image data output from the said frequency reverse conversion part 311. FIG.

  According to the above configuration, the frequency component adjustment unit (frequency-specific intensity correction unit 310) applies the intensity of the spatial frequency component acquired from the frequency conversion unit 302 based on the character size determination result in the determination unit 304. Amplify or reduce. The frequency inverse transform unit 311 inversely transforms the spatial frequency component processed by the frequency component adjustment unit (frequency-specific intensity correction unit 310) into image data of a pixel value and outputs the image data. The image data processing unit processes the image data output from the frequency inverse transform unit 311. The image data processing unit is a subsequent processing unit of the frequency inverse transform unit 311 included in the image processing apparatus.

  According to the above configuration, the subsequent image data processing unit of the frequency inverse transform unit 311 reflects the determination result of the character size by the determination unit 304 and performs good image processing according to the size of the characters included in the image data. Is possible. For example, the frequency component adjustment unit (frequency-specific intensity correction unit 310) weakens the high frequency component when it is determined that the character size is large, and the low frequency when it is determined that the character size is small. By performing processing such as weakening the components, subsequent filter processing can be facilitated.

  The image processing apparatus according to aspect 5 of the present invention may be configured such that, in the above aspect 4, the image data processing unit switches processing on image data in accordance with a character size determination result in the determination unit 304.

  According to the above configuration, the image data processing unit can perform favorable image processing according to the size of characters included in the image data, reflecting the character size determination result by the determination unit 304.

  The image processing apparatus according to aspect 6 of the present invention is the image processing apparatus according to aspect 5, wherein the image data processing unit includes a compression unit (image compression processing unit 41) that compresses image data, and the compression unit includes the determination unit 304. The image compression setting may be switched according to the determination result of the character size.

  According to the above configuration, the compression unit (image compression processing unit 41) switches the setting of image compression according to the determination result of the character size in the determination unit 304. For example, when there is no character, the compression unit can improve the storage efficiency and transmission efficiency of image data by performing compression processing of image data at a higher compression rate than usual. On the other hand, when a character exists, the image quality of image data including the character can be maintained or improved by reducing the compression rate according to the character size.

The image processing method of the present invention includes a frequency conversion step of converting image data into a spatial frequency component;
A frequency analysis step for obtaining the intensity of the spatial frequency component, and comparing the intensity of the high frequency component belonging to a relatively high frequency out of the intensity of the spatial frequency component with a predetermined threshold, and the intensity of the high frequency component Is larger than the predetermined threshold, the character size included in the image data is determined to be a relatively small size, and the intensity of the high frequency component is equal to or lower than the predetermined threshold. And a determination step of determining a character size included in the data as a relatively large size.

  According to the said structure, there exists an effect | action similar to the image processing apparatus of aspect 1, and an effect.

  The image processing apparatus according to each aspect of the present invention may be realized by a computer. In this case, a program that causes the computer to realize the image processing apparatus by causing the computer to operate as each unit included in the image processing apparatus. And a computer-readable recording medium on which it is recorded also fall within the scope of the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used in an apparatus including a processing unit that processes image data including characters, such as a printer, a copier, and a multifunction peripheral.

1 color image input device 2 color image processing device (image processing device)
3 Color image output device 4 Operation panel 5 Color image processing device (image processing device)
6 Color image output device 7 Control unit 30 Character size determination unit 41 Image compression processing unit (image data processing unit)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Image forming apparatus 300 Memory | storage part 301 Pixel value reading part (division | segmentation process part)
302 Frequency conversion unit 303 Frequency analysis unit 304 Determination unit 305 Correction unit 306 Density determination unit 307 Adjacent pixel correction unit 308 Diagonal direction determination unit 309 Mask processing unit 310 Frequency-specific intensity correction unit (frequency component adjustment unit)
311 Frequency inverse transform unit 312 Output determination unit

Claims (10)

A frequency converter that converts image data into spatial frequency components;
A frequency analysis unit for obtaining the intensity of the spatial frequency component;
Of the intensities of the spatial frequency components, the intensities of the high frequency components belonging to a relatively high frequency are compared with a predetermined threshold, and the intensity of the high frequency components is greater than the predetermined threshold. While determining the character size included in the data as a relatively small size, when the intensity of the high frequency component is equal to or less than the predetermined threshold, the character size included in the image data is set as a relatively large size An image processing apparatus comprising: a determination unit for determining.   2. The image according to claim 1, wherein the determination unit determines a character size for each of a main scanning direction and a sub-scanning direction of the high-frequency component and determines a character size based on the determination result. Processing equipment. A division processing unit is provided in front of the frequency conversion unit, and the division processing unit divides the image data into a plurality of blocks, each of the blocks includes a plurality of pixels in the main scanning direction and the sub-scanning direction,
The image according to claim 1, wherein the determination unit determines a character size for each block, and determines a character size of image data based on a determination result of the character size for each block. Processing equipment. A frequency component adjustment unit that amplifies or reduces intensity based on the determination result of the character size in the determination unit with respect to the spatial frequency component acquired from the frequency conversion unit,
A frequency inverse transform unit that inversely transforms and outputs the spatial frequency component processed by the frequency component adjustment unit to image data of pixel values;
The image processing apparatus according to claim 1, further comprising: an image data processing unit that processes image data output from the frequency inverse transform unit.   The image processing apparatus according to claim 4, wherein the image data processing unit switches processing for the data in accordance with a character size determination result in the determination unit. The image data processing unit includes a compression unit that compresses image data,
The image processing apparatus according to claim 5, wherein the compression unit switches setting of image compression according to a determination result of the character size in the determination unit.   An image forming apparatus comprising the image processing apparatus according to claim 1. A frequency conversion step of converting image data into a spatial frequency component;
A frequency analysis step for determining the intensity of the spatial frequency component;
Of the intensities of the spatial frequency components, the intensities of the high frequency components belonging to a relatively high frequency are compared with a predetermined threshold, and the intensity of the high frequency components is greater than the predetermined threshold. While determining the character size included in the data as a relatively small size, when the intensity of the high frequency component is equal to or less than the predetermined threshold, the character size included in the image data is set as a relatively large size An image processing method comprising: a determination step of determining.   A program for causing a computer to function as the image processing apparatus according to claim 1, wherein the program causes the computer to function as each of the above-described units.   A computer-readable recording medium on which the program according to claim 9 is recorded.

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