JP2016123070A - Image processing apparatus, image processing method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus performing correction of the position and deformation of a multi-value image, and prevent the occurrence of white void around characters and line drawings to output high-quality images even when a background is other than white.SOLUTION: There is provided an image processing apparatus performing geometric correction to input image data, the image processing apparatus comprising: geometric correction means that creates a plurality of pieces of pixel value correction image data having different pixel values from each other on the basis of object information on the image data; composition means that selects, from the plurality of pieces of pixel value correction image data created by the geometric correction means, a pixel value to be applied for each of pixels to create correction image composition data; and pseudo gradation processing means that performs pseudo gradation processing on the correction image composition data created by the composition means.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image processing apparatus, an image processing method, and a program.

  In an electrophotographic image forming apparatus, registration deviation or skew deviation occurs, and in an apparatus capable of printing on both sides, front and back deviations occur. Therefore, a correction technique for measuring the amount of deviation and correcting the position or deformation of an image so as to cancel it is already known. As examples of such correction techniques, parallel movement, magnification correction, distortion correction, inter-color shift correction, front / back shift correction, and the like are known.

  In the correction technique as described above, correction is performed on a multi-value image before pseudo gradation processing, and correction is performed on a small-value image after pseudo gradation processing described in Patent Document 1, for example. Things are known. In general, a process for correcting a multi-valued image is inherently less likely to cause an image quality abnormality than a process for correcting a low-valued image, and relatively free image deformation can be performed. It has been known.

  As a specific example of performing a correction process on a multi-value image, for example, Japanese Patent Laid-Open No. 2004-228561 discloses that the color plate overlay shift due to image skew is suppressed, the thin line image is suppressed from being thickened, and the partial omission of the image is generated. For the purpose of suppressing the image, a part of the pixels constituting the image is converted into a multi-value halftone pixel corresponding to the area of the image location existing in the pixel based on the amount of deviation such as skew deviation, and for writing There has been disclosed a technique for determining a distribution in a writing matrix based on gradations of peripheral pixels when converting to writing pixels by applying a matrix (a so-called dither threshold matrix).

  However, with conventional devices that perform image position correction or deformation correction on multi-valued images, when the background is other than a white background, white spots occur around characters and line drawings, resulting in image degradation. To do.

  The present invention has been made in view of such circumstances, and in an apparatus that performs image position correction and deformation correction on a multi-valued image, even if the background is other than a white background, characters and line drawings are provided. The purpose of this is to prevent white spots from occurring in the surrounding area.

  In order to achieve the above-described object, an image processing apparatus of the present invention is an image processing apparatus that performs geometric correction on input image data, and a plurality of pixel values having different pixel values based on object information of the image data. Geometric correction means for generating pixel value corrected image data, and synthesis means for generating corrected image composite data by selecting a pixel value to be applied to each pixel from a plurality of pixel value corrected image data generated by the geometric correction means And pseudo gradation processing means for performing pseudo gradation processing on the corrected image composition data generated by the composition means.

  According to the present invention, in an apparatus that performs image position correction and deformation correction on a multi-valued image, white spots are prevented from occurring around characters and line drawings even when the background is other than a white background. It becomes possible.

It is a hardware block diagram of the image processing apparatus in embodiment of this invention. 1 is an overall configuration diagram of an image processing apparatus according to a first embodiment of the present invention. It is a schematic diagram which shows an example of the object information in 1st Embodiment of this invention. It is a schematic diagram explaining an example of the geometric correction with respect to the image distortion in 1st Embodiment of this invention. It is a block diagram of the geometric correction | amendment part in 1st Embodiment of this invention. It is a schematic diagram explaining the corresponding coordinate point calculation part in 1st Embodiment of this invention. It is a schematic diagram explaining the interpolation calculating part in 1st Embodiment of this invention. It is a schematic block diagram of the foreground / background binarization unit in the first embodiment of the present invention. It is a schematic diagram explaining the synthetic | combination part in 1st Embodiment of this invention. It is a schematic block diagram of the dot approach part in 1st Embodiment of this invention. It is a schematic diagram explaining the 1st determination part and 2nd determination part in 1st Embodiment of this invention. It is a schematic diagram explaining the threshold value determination part in 1st Embodiment of this invention. It is a flowchart which shows the geometric correction process sequence in 1st Embodiment of this invention. It is a schematic diagram which shows the specific example of the geometric correction result in 1st Embodiment of this invention. It is a schematic diagram which shows an example of the image produced | generated by the geometric correction part in 1st Embodiment of this invention. It is a flowchart which shows the foreground / background binarization processing procedure in 1st Embodiment of this invention. It is a schematic diagram which shows an example of the output result by the dot approach part in 1st Embodiment of this invention. It is a schematic diagram which shows the example of a process image in 1st Embodiment of this invention. It is a whole block diagram of the image processing apparatus in 2nd Embodiment of this invention. It is a schematic diagram which shows an example of the object information in 2nd Embodiment of this invention. It is a block diagram of the geometric correction | amendment part in 2nd Embodiment of this invention. It is a schematic diagram which shows an example of the image produced | generated by the geometric correction part in 2nd Embodiment of this invention. It is a schematic block diagram of the foreground / background binarization part in 2nd Embodiment of this invention. It is a schematic diagram which shows an example of the output result by the dot approach part in 2nd Embodiment of this invention. It is a figure explaining the parameter for the object boundary selected in the parameter selection part in 2nd Embodiment of this invention. It is a schematic diagram which shows the screen parameter determination method in FIG. It is a figure explaining the parameter for non-object boundaries selected by the parameter selection part in 2nd Embodiment of this invention. It is a schematic diagram which shows the screen parameter determination method in FIG. It is a schematic diagram which shows the example of a process image in 2nd Embodiment of this invention. It is a schematic diagram which shows the example of the conventional process image.

  An image processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the present embodiment as long as the gist of the present invention is not exceeded. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified thru | or abbreviate | omitted suitably. Note that the image processing apparatus according to the present embodiment may be applied to an image forming apparatus having an image forming function such as a multifunction peripheral, a printer, or a FAX.

  A hardware configuration of the image processing apparatus according to the present embodiment will be described with reference to FIG. The image processing apparatus according to the present embodiment includes a CPU 100, a RAM 101, a ROM 102, an NW I / F 103, an HDD 104, an input unit 105, an output unit 106, and an image forming unit as basic hardware that performs an information processing function necessary for image processing. 107.

  The CPU 100 is a processing unit that implements various processes to be described later in the image processing apparatus. The CPU 100 implements various processes by reading each processing program stored in the ROM 102 into the RAM 101 and executing it.

  The RAM 101 functions as a work memory for the CPU 100 as described above. The RAM 101 also serves as a line memory described later in the embodiment. As described above, the ROM 102 is a storage unit that stores various processing programs and various parameters necessary for processing of the image processing apparatus.

  The NW I / F 103 is a network interface for connecting the image processing apparatus to an external apparatus or an external network. As a communication form, for example, short-range wireless communication such as LAN, WAN, or NFC can be applied, regardless of whether it is wireless or wired.

  The HDD 104 is a storage unit for storing an image or the like, for example, and stores an input image or the like input from the input unit 105.

  The input unit 105 is hardware for inputting original data of an image to be formed by the image forming unit 107, and corresponds to, for example, a scanner. The output unit 106 includes a display unit that displays an image, a paper discharge unit that discharges the paper on which the image is formed by the image forming unit 107, and the like. The image forming unit 107 is an engine unit that forms an image based on the original data and the like.

[First Embodiment]
The image processing apparatus according to the first embodiment of the present invention generally calculates a pixel value after geometric correction from a value based on object information of integer value coordinates of four surrounding points, and calculates the corrected pixel value. It is to binarize. In the present embodiment, one of the binarized data is classified as the foreground and the other is classified as the background, and the pixel value corresponding to each is selected to generate an intermediate density pixel at the boundary between the foreground and the background. This prevents white spots after pseudo gradation processing.

  The overall configuration of the image processing apparatus according to the first embodiment will be described with reference to FIG. The image processing apparatus according to the present embodiment includes an input image acquisition unit 1, a rendering unit 2, a deviation amount acquisition unit 3, a geometric correction parameter setting unit 4, a geometric correction unit 5, and a foreground / background binarization unit 6. A pseudo gradation processing unit 7 and a printer output unit 8.

  The input image acquisition unit 1 acquires an input image described in a page description language.

  The rendering unit 2 interprets the page description language acquired by the input image acquisition unit 1 and converts it into a bitmap image having a gradation value of 8 bits for each color. At that time, object information such as characters, lines, graphics, and images included in the input image is also interpreted and given to each pixel.

  The deviation amount acquisition unit 3 measures and acquires how the coordinate points of the four corners change when the printer outputs without geometric correction, that is, how much. Here, an example will be described in which the amount of deviation of the back surface relative to the front surface is measured and acquired and corrected. To obtain the amount of deviation between the front and back, register marks are printed at the four corners of the front and back surfaces, and the respective coordinate points are measured. For this measurement, it is preferable to use a method of automatic measurement with a built-in sensor, or a method of manually measuring what is printed on a recording medium with a ruler and inputting the result.

  The geometric correction parameter setting unit 4 calculates mat [0] to mat [7] as geometric correction parameters from the four coordinate points of the front and back acquired by the deviation amount acquisition unit 3.

  The geometric correction unit 5 is a geometric correction unit that generates a plurality of pixel value corrected image data having different pixel values based on the object information of the input image data. The correction data generated as the plurality of pixel value correction image data is preferably multi-value correction image data having a plurality of pixel values, for example.

  Furthermore, the geometric correction unit 5 may generate a plurality of object corrected image data having different object information based on the object information of the image data. The geometric correction unit 5 preferably calculates the pixel value of the coordinate point obtained by adding a predetermined correction amount to the coordinate point calculated corresponding to the coordinate point of the input image data. Further, it is preferable that the geometric correction unit 5 calculates the pixel value of the coordinate point obtained by adding a predetermined correction amount to the coordinate point of the object information of the image data.

  By applying mat [0] to mat [7] as geometric correction parameters, correction is performed in anticipation of misalignment or distortion that occurs during output. Here, foreground and background pixels of the input image are identified based on the object information, and a plurality of types of images including a foreground / background composition ratio image to be described later are generated for use in the foreground / background binarization unit 6. . The geometric correction unit 5 in the present embodiment functions as preprocessing of the foreground / background binarization unit 6 of the next block.

  The foreground / background binarization unit 6 performs dot alignment processing on the foreground / background composition ratio image, and generates an image in which the object boundary is binarized with the foreground and background gradation values.

  The pseudo gradation processing unit 7 performs screen processing on the image in which the object boundary is binarized with the foreground and background gradation values, that is, the corrected image composite data, and binarizes it into white pixels and black pixels, and outputs to the printer. The unit 8 outputs the printer.

  The pseudo gradation processing unit 7 switches the screen to be applied according to the object information. When the object information is characters or lines, a screen of about 300 lines is applied, and when the object information is graphics or images, a screen of about 200 lines is applied. The object information to be referred to at this time is also the information after being processed by the geometric correction unit 5 and the foreground / background binarization unit 6 and corresponds to the image at that time.

  An example of object information in the present embodiment will be described with reference to FIG. In the present embodiment, the object information includes four types of characters, lines, graphics, and images. If the background of the character or line is a white background or a color background and the density is uniform, the object information in the background portion is a graphic.

  In the present embodiment, the object information represented by 2 bits is used. As the object information, 01 for a character, 10 for a line, 11 for a graphic, and 00 for an image are provided for each pixel. It is preferable to prioritize the object information in advance. In this embodiment, characters, lines, graphics, and images are used in descending order of priority.

  Next, geometric correction for image distortion in the present embodiment will be described with reference to FIG. On the left side, an output image (2) without correction is represented by a solid line as an example of image distortion that occurs when the input image (1) represented by a broken line is output to the printer without geometric correction. On the right side, the printer output image (4) is represented by a broken line, and the image (3) corrected in anticipation of image distortion is represented by a solid line. The reversely corrected image (3) is an image for making the printer output image (4) the same as the input image (1).

  For example, in the case of front-back misalignment, the input image (1) is the front side, the output image (2) is the back side output image without geometric correction, the reversely corrected image (3) is the back side geometrically corrected image, the printer output image ( 4) is an image obtained by outputting the reversely corrected image (3) to the printer. Here, it is assumed that distortion does not occur on the front surface even when output from a printer.

  In the present embodiment, the shift amount acquisition unit 3 acquires the coordinates of the four corners of the input image (1) and the coordinates of the four corners of the output image (2), and the geometric correction parameter setting unit 4 causes image distortion that occurs during printer output. The above-described mat [0] to mat [7] are set as geometric correction parameters for performing reverse correction in anticipation and generating an image of the reverse-corrected image (3).

  Next, the configuration of the geometric correction unit 5 in the present embodiment will be described with reference to FIG. The geometric correction unit 5 includes a corresponding coordinate point calculation unit 50, a four-point extraction unit 51, a first object extraction unit 52, a second object extraction unit 53, an interpolation calculation unit 54, and a foreground pixel value selection unit. 55, a background pixel value selection unit 56, and a storage unit 57.

  The corresponding coordinate point calculation unit 50 converts the coordinate point (X, Y) on the input image (1) corresponding to the coordinate point (x, y) on the inversely corrected image (3) to the geometric correction parameter mat [ 0] to mat [7] are applied. The coordinate point (X, Y) is preferably calculated as a real value having a value after the decimal point.

  The four-point extraction unit 51 extracts four neighboring points surrounding the coordinate point (X, Y) based on the values of the integer parts of X and Y.

  The first object extraction unit 52 extracts the object information having the highest priority from the object information given to the four points, and the coordinate point (x, y) of the object priority image (d) having the highest priority. Is stored in the line memory of the storage unit 57 as the pixel value. In addition to the extracted object information, the first object extraction unit 52 sends four gradation values to the foreground pixel value selection unit 55 in the subsequent stage.

  The second object extraction unit 53 extracts the object information having the lowest priority from the object information given to the four points, and the coordinate point (x, y) of the object priority image (e) having the lowest priority. Is stored in the line memory of the storage unit 57 as the pixel value. Further, the second object extraction unit 53 sends the four gradation values to the background pixel value selection unit 56 in the subsequent stage in addition to the extracted object information.

  The interpolation calculation unit 54 performs interpolation calculation based on the object information of the surrounding four points, and stores it in the line memory of the storage unit 57 as the pixel value of the coordinate point (x, y) of the foreground / background composition ratio image (a).

  The foreground pixel value selection unit 55 extracts the gradation value of the pixel having the object information extracted by the first object extraction unit 52 from four points, and the pixel at the coordinate point (x, y) of the foreground priority image (b) The value is stored in the line memory of the storage unit 57 as a value.

  The background pixel value selection unit 56 extracts the gradation value of the pixel having the object information extracted by the second object extraction unit 53 from four points, and the pixel at the coordinate point (x, y) of the background priority image (c) The value is stored in the line memory of the storage unit 57 as a value. When all the four extracted points are the same object, the foreground priority image (b) and the background priority image (c), the high priority object priority image (d), and the low priority object priority image (e) The pixel values of are the same.

  Next, the corresponding coordinate point calculation unit 50 in the present embodiment will be described with reference to FIG. The corresponding coordinate point calculation unit 50 calculates the coordinate point (X, Y) corresponding to (x, y) by applying the following two-dimensional projective transformation expression, Expression 1 and Expression 2.

  In the geometric correction in the present embodiment, the gradation value and object information of the coordinate point (X, Y) in the input image (1) are obtained by interpolation calculation, and the coordinate point (x, y) of the image (3) subjected to reverse correction is obtained. This is done by reducing as gradation values and object information.

  Next, the interpolation calculation unit 54 in the present embodiment will be described with reference to FIG. First, the four-point extraction unit 51 calculates (X0, Y0) coordinate points corresponding to the integer part (X, Y), and (X0 + 1, Y0), (X0, Y0 + 1), (X0 + 1, Y0 + 1). Four coordinate points are extracted.

The interpolation calculation is performed on the pixel value as follows. Here, the pixel values of (X, Y) are calculated by applying the weights wx and wy to the four pixel values. The decimal part of X corresponds to wx, and the decimal part of Y corresponds to wy.
Pixel value of (x, y) = pixel value of (X, Y) = pixel value of (X0, Y0) × (1-wx) × (1-wy) + (X0 + 1, Y0) pixel value × wx × (1-wy) + (X0, Y0 + 1) pixel value × (1-wx) × wy + (X0 + 1, Y0 + 1) pixel value × wx × wy

The interpolation calculation performed by the interpolation calculation unit 54 in this embodiment is not performed on the pixel value, but based on the object information. That is, the interpolation calculation in this embodiment is performed as follows.
Pixel value of image (a) (x, y) = value based on object information of (X0, Y0) × (1-wx) × (1-wy) + value based on object information of (X0 + 1, Y0) × Value based on object information of wx × (1-wy) + (X0, Y0 + 1) × Value based on object information of (1-wx) × wy + (X0 + 1, Y0 + 1) × wx × wy

  The value based on the object information is 255 when the object information of the corresponding pixel is the highest priority object extracted by the first object extraction unit 52, and is 0 when the object information is other than that. . However, if all four points are the same object, it is forcibly set to 0.

  Next, a schematic configuration of the foreground / background binarization unit 6 in the present embodiment will be described with reference to FIG. The foreground / background binarization unit 6 in the present embodiment includes a dot shift unit 60 and a synthesis unit 61.

  The dot gathering unit 60 is a dot gathering unit that generates binary image data obtained by binarizing the pixel values of the multi-value corrected image data. More specifically, the dot alignment unit 60 performs dot alignment processing on the foreground / background composition ratio image (a) with reference to the background priority image (c), and performs 0 (white pixel) or 255 (black pixel). ) Is a binary image (a ′) after dot alignment. Here, the foreground / background composition ratio image (a) and the background priority image (c) refer to 4 × 4 pixels.

  The synthesizing unit 61 is a synthesizing unit that selects the pixel value to be applied for each pixel from the plurality of pixel value corrected image data generated by the geometric correcting unit 5 and generates corrected image synthesized data.

  More specifically, the synthesis unit 61 selects a foreground priority image (b) or a background priority image (c) for each pixel based on the image (a ′) after dot alignment that is binary image data. Then, a corrected 8-bit image is generated.

  Similarly, the compositing unit 61 selects an object priority image (d) having a high priority or an object priority image (e) having a low priority for each pixel based on the image (a ′) after dot alignment, and performs correction. After-object information is generated. Here, 2 × 2 pixels are obtained for the corrected 8-bit image and the corrected object information.

  The combining unit 61 will be further described with reference to FIG. This figure shows, from the left, the pixel value of the image (a ′) after dot alignment, the 8-bit image after correction, and the object information after correction, and is selected for the pixel value of the image (a ′) after dot alignment. The correspondence relationship between the corrected 8-bit image and the corrected object information is shown.

  The 8-bit image after correction is based on the pixel value of the image (a ′) after dot alignment. If the pixel value is 255, the foreground priority image (b) is selected. If the pixel value is 0, the background priority image (c ) Is composed of selected pixel values.

  The corrected object information is based on the image (a ′) after dot alignment, and if the pixel value is 255, the object priority image (d) having a high priority is selected, and if the pixel value is 0, the priority is selected. Is composed of selected pixel values.

  That is, in the present embodiment, the combining unit 61 similarly corrects the object information so that the corrected 8-bit image and the object information completely correspond to each other after the correction. Note that the 8-bit image after correction and the object information after correction determined here are both input to the pseudo gradation processing unit 7 in the subsequent stage. In the present embodiment, it is preferable that the pseudo gradation processing is performed by switching the screen to be applied to the corrected 8-bit image based on the corrected object information.

  Next, the dot alignment unit 60 will be further described with reference to FIG. The dot alignment unit 60 includes a first determination unit 600, a second determination unit 601, a threshold value determination unit 602, and a threshold value processing unit 603.

  The first determination unit 600 is a first determination unit that determines a screen used for binarization processing. More specifically, the first determination unit 600 applies a horizontal line screen to perform dot alignment, applies a vertical line screen to perform dot alignment, or applies an oblique line screen. It is determined from the background priority image (c) whether or not to perform dot alignment.

  The second determination unit 601 is a second determination unit that determines the dot alignment direction in the binarization process. More specifically, the second determination unit 601 determines whether the upper left, upper right, lower left, or lower right is to be used for dot alignment when applying an oblique line screen to the background priority image (c). Judgment from.

  The threshold determination unit 602 determines a dither threshold to be applied to 2 × 2 pixels according to the determination results of the first determination unit 600 and the second determination unit 601.

  The threshold processing unit 603 applies the dither threshold determined by the threshold determination unit 602 to the foreground / background composition ratio image (a), and if it is equal to or greater than the threshold, it is 255 (black pixel), and if it is less than the threshold, 0 (white). Pixel).

  The first determination unit 600 and the second determination unit 601 will be described in more detail with reference to FIG. Here, the determination is made with reference to 4 × 4 pixels of the background priority image (c).

  The first determination unit 600 calculates the average value of the pixels of p00, p01, p10, p11, p20, p21, p30, and p31 and sets it as the left average, and p02, p03, p12, p13, p22, p23, p32, The average value of the pixels at p33 is calculated and set as the right average.

  In addition, the first determination unit 600 calculates an average value of pixels of p00, p01, p02, p03, p10, p11, p12, and p13, and sets it as an upper average, and p20, p21, p22, p23, p30, p31, The average value of pixels of p32 and p33 is calculated and set as the lower average.

  Here, the absolute value of the difference between the left average and the right average is defined as the left-right difference, and the absolute value of the difference between the upper average and the lower average is defined as the vertical difference. The first determination unit 600 determines that the vertical line screen is applied if the left / right difference <up / down difference, and determines that the horizontal line screen is applied if the left / right difference> up / down difference. = If the difference is up and down, it is determined that an oblique line screen is applied.

  On the other hand, the second determination unit 601 calculates the average value of the pixels of p00, p01, p10, and p11, calculates the average value of the upper left, calculates the average value of the pixels of p02, p03, p12, and p13, and sets the average value of the upper right. . Further, the second determination unit 601 calculates the average value of the pixels of p20, p21, p30, and p31, sets the lower left average, calculates the average value of the pixels of p22, p23, p32, and p33, and calculates the lower right average. To do. Then, the second determination unit 601 determines the direction having the maximum average value among the upper left, upper right, lower left, and lower right as the approach direction.

  The threshold value determination unit 602 will be described with reference to FIG. First, as a premise, a dither threshold matrix for a vertical line screen and a dither threshold matrix for a horizontal line screen having a size of about 32 × 32 are prepared in advance.

  When the first determination unit 600 determines that the vertical line screen is to be applied, the threshold value determination unit 602 dither threshold value for 2 × 2 pixels corresponding to the corresponding pixel position from the vertical line screen dither threshold value matrix. To extract.

  In addition, when the first determination unit 600 determines that the horizontal line screen is applied, the threshold value determination unit 602 corresponds to 2 × 2 pixels corresponding to the corresponding pixel position from the horizontal line screen dither threshold value matrix. Extract dither threshold.

  Further, when the first determination unit 600 determines that the oblique line screen is applied, the threshold value determination unit 602 corresponds to 2 × 2 pixels corresponding to the corresponding pixel position from the vertical line screen dither threshold value matrix. Dither thresholds are extracted and rearranged according to the dot alignment direction as shown in the figure.

  When the second determination unit 601 determines that the shifting direction is upper right, the threshold determination unit 602 arranges the smaller dither threshold at the upper right and the larger dither threshold at the lower left of the diagonal. Further, the threshold value determination unit 602 places the average value of the smaller dither threshold value and the larger dither threshold value for the remaining two. The same applies to the case where the shifting direction is lower left, upper left, and lower right.

  Next, the geometric correction processing procedure in this embodiment will be described with reference to FIG. First, the geometric correction parameter setting unit 4 sets the coordinate point (x, y) after geometric correction to an initial value (0, 0) (step S1, step S2).

  Next, the geometric correction unit 5 performs geometric correction (step S3). The result of the geometric correction process by the geometric correction unit 5 is stored in the line memory of the storage unit 57 (step S4). The geometric correction unit 5 “+1” the coordinate point in the x direction. The geometric correction unit 5 repeats the processing from step S3 to step S5 until the coordinate position of x exceeds the number of pixels in the x direction (step S8).

  Next, the geometric correction unit 5 “+1” the coordinate point in the y direction (step S6). When the coordinate position of y does not exceed the number of pixels in the y direction (step S9, NO), the geometric correction unit 5 determines whether y is an even number (step S10). When the geometric correction unit 5 determines that y is an even number (step S10, YES), the process proceeds to the foreground / background binarization unit 6 to acquire the foreground / background binarization result for two lines (step S7).

  When the geometric correction unit 5 determines that y is not an even number (step S10, NO), it repeats the processing from step S2. That is, the geometric correction unit 5 repeats the processing from step S2 to step S6 until the y coordinate position exceeds the number of pixels in the y direction (step S9). In the accumulation process in step S5, the latest four lines of results may be accumulated, and the previous results may be discarded.

  Next, a specific example of the geometric correction processing result in the present embodiment will be described with reference to FIG. As shown in this figure, for the four surrounding pixels represented by ◯, (a) to (e) corresponding to the coordinate point (X, Y) of the input image (1) in which “x” is written in ◯. ) Is set as wx = 0.75 and wy = 0.5 as follows.

  The foreground / background composition ratio image (a) is 159 with the decimal part of 255 × 0.25 × 0.5 + 255 × 0.75 × 0.5 + 255 × 0.25 × 0.5 = 159.375 rounded down.

  The object priority image (d) having a high priority is 01 indicating that it is a character object, and the foreground priority image (b) has a pixel value 255 of the pixel of the character object.

  On the other hand, the object priority image (e) having a low priority is 11 indicating that it is a graphic object, and the background priority image (c) has a pixel value 80 of the pixel of the graphic object.

  Next, images (a) to (c) generated by the geometric correction unit 5 in the present embodiment will be described with reference to FIG. In this figure, an image representing hiragana “a” is used as an example.

  The foreground / background composition ratio image (a) is a multivalued image having a value of 0 to 255 at the edge portion of the object boundary. The foreground priority image (b) is an image in which characters (or lines) are slightly thicker than the input image, and the background priority image (c) is in which characters (or lines) are slightly narrower than the input image. The resulting image will be.

  The object priority image (d) having a high priority is an object information image corresponding to (b), and the object priority image (e) having a low priority is an object information image corresponding to (c).

  Next, a processing procedure in the foreground / background binarization unit 6 in the present embodiment will be described with reference to FIG. First, the foreground / background binarization unit 6 sets x to an initial value 0 (step S71).

  Next, the foreground / background binarization unit 6 cuts out a 4 × 4 pixel geometric correction result from the latest four lines of geometric correction results stored in the line memory of the storage unit 57 (step S72). At this time, the foreground / background binarization unit 6 cuts out the result of the coordinate points of x−1, x, x + 1, and x + 2 in the x direction. In the case where x-1 = -1 as in the case of x = 0 and there is no coordinate point, the pixel values of (a) to (e) as the geometric correction results are all 0. To do.

  The foreground / background binarization unit 6 refers to the geometric correction result of 4 × 4 pixels and acquires the foreground / background binarization result of 2 × 2 pixels (step S73). The foreground / background binarization unit 6 adds +2 in the x direction (step S75). Then, the foreground / background binarization unit 6 repeats the processing from step S72 to step S74 until the coordinate position of x exceeds the number of pixels in the x direction.

  Next, the output of the dot alignment unit 60 in the present embodiment will be described with reference to FIG. Here, hiragana “a” is used as an example. The dot shifting unit 60 converts (a), which is a multi-valued image having a value of 0 to 255 at the edge portion of the object boundary, into a binary image of 0 (white pixel) or 255 (black pixel).

  Since dot alignment is a conversion from a multi-valued image to a binary image, the horizontal line edge is binarized by applying the vertical line screen, and the horizontal line screen is applied to the vertical line edge. It is preferable to carry out by a method of applying screen processing according to direction to the image of (a) such as binarization.

  Next, an example of a processed image in the present embodiment will be described with reference to FIG. For the black line after the foreground / background binarization processing, that is, a part of the black character, an image is generated by the combining unit 61 using the result of the dot shift processing shown in FIG. For this reason, the edge portion has a jagged shape. In the object information, a jagged mountain portion (hereinafter referred to as “black character portion”) is converted into a character object and a jagged valley portion is converted into a graphic object according to the image.

  When the pseudo gradation process is performed on the image after the foreground / background binarization process, the black character portion has a gradation value of 255, so that even if the screen pattern for the character object is applied, it is substantially unchanged, that is, is not converted. Only the part is replaced with a screen pattern for graphic objects. As shown in the figure, white spots do not occur at the object boundary.

  Note that the jaggedness of the edge portion is a considerably high frequency in pixel units, and it cannot be visually confirmed with the output resolution of recent printers. In the example of FIG. 18, there is an effect that a straight line appears to be drawn on the screen pattern of the color background.

  FIG. 18A is a diagram assuming geometric correction in which a horizontal line constituting a black character is shifted downward or upward by 0.5 pixels, and a jagged shape occupies 50% above and below the line drawing. . For example, when geometric correction is performed by shifting by 0.25 pixels downward, the line drawing has a jagged shape with 75% at the top and 25% at the bottom as shown in FIG.

  Also, it is not always a uniform jagged pattern. When geometric correction with rotation is performed, or when the line drawing of the input image originally has an inclination, a jagged shape whose ratio changes in a gradation as shown in FIG.

  What kind of jagged shape is determined by the result of dot alignment shown in FIG. Based on the dot shift processing result shown in FIG. 17, by selecting the foreground priority image (b) or the background priority image (c) of FIG. 15 in units of pixels according to the table shown in FIG. This is a foreground image, that is, an image binarized into gradation values of characters and background images in this example.

[Second Embodiment]
Next, an image processing apparatus according to the second embodiment of the present invention will be described. In addition, description about the structure which overlaps with 1st Embodiment is abbreviate | omitted.

  In the first embodiment, by performing dot shifting processing on a binary image represented by shading after screen processing, the periodic pattern of shading may be lost and moire may occur.

  In the second embodiment, a configuration for preventing the occurrence of the above moire is added to the configuration of the first embodiment.

  That is, in the second embodiment, on the object boundary such as the boundary between the character and the background based on the object information, the dot omission processing for preventing the white omission is performed, while the mesh constituting the shading that is a graphic object. By applying a concavo-convex pattern having a moire suppressing effect at the boundary of the hanging dots, the periodicity of the shaded dots is destroyed and the occurrence of moire is prevented.

  The overall configuration of the image processing apparatus of the image processing apparatus according to the second embodiment will be described with reference to FIG. Here, a configuration of an object boundary determination unit 62 and a parameter selection unit 63 is newly added between the geometric correction unit 5 and the foreground / background binarization unit 6 of the configuration in the first embodiment shown in FIG.

  Based on the object information, the object boundary determination unit 62 determines whether or not the target pixel block made up of 2 × 2 pixels is an object boundary region including a boundary between different objects.

  The parameter selection unit 63 selects a screen parameter determined by the first determination unit 600 based on whether the target coordinate in the image data is an object boundary or a non-object boundary that is a boundary of a shaded dot. Parameter selection means. The parameter selection unit 63 selects a parameter based on the result of the object boundary determination unit 62.

  The parameter selection unit 63 selects a screen parameter from a regularly arranged parameter group when the target coordinate is an object boundary. In addition, when the target coordinate is a non-object boundary, the parameter selection unit 63 selects a screen parameter from an irregularly arranged parameter group. Details of each parameter group will be described later.

  The foreground / background binarization unit 6 performs a dot shifting process on the foreground / background composition ratio image using the parameters selected by the parameter selection unit 63 and binarizes the foreground / background gradation values. Generate an image.

  The pseudo gradation processing unit 7 performs screen processing on the image binarized with the foreground and background gradation values to binarize the white pixel and the black pixel, and the printer output unit 8 outputs the printer.

  Next, the object information will be described with reference to FIG. For example, in the shading used when creating a chart such as a graph, all dots constituting the mesh and the background are all graphics and are assigned to each pixel as a graphic object.

  Next, determination processing performed by the edge determination unit 58, the foreground / background pixel value selection unit 59, and the object boundary determination unit 62 added to the image processing apparatus according to the second embodiment will be described with reference to FIG.

  Here, the interpolation calculation unit 54 performs an interpolation calculation based on the surrounding four points of object information and the edge determination result.

  The edge determination unit 58 is an edge determination unit that determines whether or not the target pixel is an edge portion. As a result, an edge determination result is given to each pixel in addition to the 8-bit image and object information. The method for determining whether or not the target pixel is an edge portion refers to 5 × 5 pixels centered on the target pixel, and if the difference between the maximum value and the minimum value is greater than or equal to a predetermined value, it is an edge. Judged as an edge.

  When the object information extracted by the first object extraction unit 52 and the object information extracted by the second object extraction unit 53 indicate different objects, the object boundary determination unit 62 is configured with four points. It is determined that the pixel block is an object boundary. On the other hand, when the extracted object information points to the same object, that is, when all four points are the same object, it is determined that the pixel block of interest constituted by the four points is a non-object boundary.

  The foreground / background pixel value selection unit 59 extracts the gradation value of the pixel having the object information extracted by the first object extraction unit 52 from four points when the target pixel block is an object boundary, and outputs the foreground priority image. (B) is stored in the line memory of the storage unit 57 as the pixel value of the coordinate point (x, y). In addition, the gradation value of the pixel having the object information extracted by the second object extraction unit 53 is extracted from four points, and the pixel value of the coordinate point (x, y) of the background priority image (c) is stored in the storage unit 57. Accumulate in line memory.

  On the other hand, if the pixel block of interest is a non-object boundary, the gradation value of the edge pixel is extracted from four points according to the result of the edge determination unit 58, and the coordinate points (x, y) of the foreground priority image (b) ) Is stored in the line memory of the storage unit 57. In addition, the gradation values of the non-edge pixels are extracted from the four points and stored in the line memory of the storage unit 57 as the pixel values of the coordinate point (x, y) of the background priority image (c). When all four points are edge pixels, (c) has the same value as (b). When all four points are non-edge pixels, (b) has the same value as (c).

  In a processing flow in which the output resolution is higher than the input resolution, resolution conversion to the output resolution is performed before geometric correction. For example, when the input resolution is 1200 dpi and a registration shift of 0.5 dots is corrected, pixels of intermediate gradation are generated at the edge portion. Therefore, when the output resolution is 2400 dpi, the registration deviation corresponding to 1 dot after conversion to 2400 dpi, that is, 0.5 dot at 1200 dpi is corrected. As a result, intermediate gradation pixels are not generated at the edge portion. Therefore, image quality degradation due to geometric correction can be reduced.

  The resolution conversion is preferably performed between the rendering unit 2 and the geometric correction unit 5.

  The process of the interpolation calculation part 54 in 2nd Embodiment is demonstrated with reference to FIG. The interpolation calculation performed by the interpolation calculation unit 54 in the second embodiment is performed based on the edge determination result in addition to the object information.

  When the extracted pixel block of interest consisting of four points is an object boundary, the calculation formula described in the first embodiment is used. The value based on the edge determination result is 255 when the corresponding pixel is an edge, and 0 when the pixel is a non-edge.

On the other hand, when the extracted pixel block of interest consisting of four points is a non-object boundary, the following equation is used.
Pixel value of (x, y) of image (a) = value based on edge determination result of (X0, Y0) × (1-wx) × (1-wy)
+ Value based on edge determination result of (X0 + 1, Y0) × wx × (1-wy) + value based on edge determination result of (X0, Y0 + 1) × edge of (1-wx) × wy + (X0 + 1, Y0 + 1) Value based on determination result × wx × wy

  Next, images (a) to (c) generated by the geometric correction unit 5 will be described with reference to FIG.

  The foreground / background composition ratio image (a) is a multivalued image having a value of 0 to 255 at the edge of a character or line drawing object boundary or a shaded non-object boundary. The foreground priority image (b) is an image in which characters (or lines) or shaded dots are slightly thicker than the input image. The background priority image (c) is an image in which characters (or lines) or shaded dots are slightly narrower than the input image.

  The object priority image (d) having a high priority is an object information image corresponding to (b). The object priority image (e) having a low priority is an object information image corresponding to (c).

  Next, a configuration in which the parameter selection unit 63 is added to the configuration shown in FIG. 8 will be described with reference to FIG. The parameter selection unit 63 selects the vertical line and horizontal line screen parameters to be applied by dot alignment according to the object boundary determination result. The dot aligning unit 60 performs dot aligning processing using the selected parameter with respect to the foreground / background composition ratio image (a) with reference to (c) to obtain 0 (white pixel) or 255 (black pixel). An image (a ′) after dot alignment, which is a binary image, is generated.

  Next, the output of the dot alignment unit 60 in the second embodiment will be described with reference to FIG. A multi-valued image (a) having a value of 0 to 255 at an edge of an object boundary such as a character or line drawing or a non-object boundary such as a shaded area is 0 (white pixel) or 255 (black pixel). ) To a binary image.

  Since dot alignment is a conversion from a multi-valued image to a binary image, the horizontal line edge is binarized by applying the vertical line screen, and the horizontal line screen is applied to the vertical line edge. This is performed by applying a direction-specific screen process to the image (a), such as binarization.

  Next, the object boundary parameters selected by the parameter selection unit 63 will be described with reference to FIG. When the pixel block of interest is an object boundary, the vertical line and horizontal line screen parameters to be applied by dot alignment are selected from the parameter array shown in FIG.

  When the parameter array in FIG. 25 is Dit (n), n = 0,..., 63, n is an even element, and a numerical value of less than 128 is entered, and n is an odd element. It is configured as a regular parameter group so that a small value and a large value are arranged alternately. For example, when threshold processing is performed by applying Dit (n) as it is to the horizontal line of the pixel value 128, 255, 0, 255, 0, 255, 0, 255, 0,. Is output, resulting in a high-frequency black and white pattern. Dit (n) is a parameter array that is intended to be converted into a high-frequency monochrome pattern (uneven pattern).

  Vertical and horizontal line screens applied to four points of coordinates (x, y), (x + 1, y), (x, y + 1), (x + 1, y + 1) (x and y are even numbers) after geometric correction Is shown in FIG. x% 64 is the remainder of dividing x by 64. Therefore, the parameter selection unit 63 selects four parameters, Dit (x% 64), Dit (x% 64 +1), Dit (y% 64), and Dit (y% 64 + 1) from the parameter array of FIG. Good.

  Next, the non-object boundary parameters selected by the parameter selection unit 63 will be described with reference to FIG. When the pixel block of interest is a non-object boundary, the vertical line and horizontal line screen parameters to be applied by dot alignment are selected from the parameter array shown in FIG.

  In FIG. 27, when the parameter array is Dit_r (m) (n), m = 0,..., 7, n = 0,..., 63, an irregular parameter group so that numerical values are irregularly arranged for each row. It is configured as. For example, when threshold processing is performed by applying Dit_r (m) (n) as it is to a horizontal line having a pixel value of 128, when the parameters in the first row are used, 32 pixels out of 64 pixels are white and 32 pixels are black. Pattern is output. When the parameters of other rows are used, the ratio of black and white is the same, but the pattern is different from that when the first row is used.

  In any case, 0, 255, 0, 255, 0, 255, 0, 255,. It is not a regular output. Dit_r (m) (n) is a parameter array that is intended to be converted into an irregular and highly dispersible black and white pattern, that is, a concavo-convex pattern.

  Vertical line screen and horizontal line screen applied to four points of coordinates (x, y), (x + 1, y), (x, y + 1), (x + 1, y + 1) (x and y are even numbers) after geometric correction Is shown in FIG.

  Accordingly, the parameter selection unit 63 performs Dit_r ((y / 2)% 8) (x% 64), Dit_r ((y / 2)% 8) (x% 64 + 1), Dit_r ((x / 2)% 8) Four (y% 64) and Dit_r ((x / 2)% 8) (y% 64 + 1) may be selected from the parameter array in FIG.

  For example, when x = 2 and y = 4, Dit_r (2) (2) and Dit_r (2) (3) as vertical line screen parameters and Dit_r (1) (4) as horizontal line screen parameters. Dit_r (1) (5) is selected.

  If threshold processing is performed using the parameter selected here, it may be possible to form a 2-dot long line, but since the parameter selected here is applied to the 1-dot width portion of the edge, There is no case in which a cut line of 2 dot length unit is formed on the output image.

  Next, the threshold value determination unit 602 according to the second embodiment will be described with reference to FIG. When the first determination unit 600 determines that the vertical line screen is to be applied, the vertical line screen parameter selected by the parameter selection unit 63 is determined as a threshold to be applied by the threshold processing unit 603.

  On the other hand, if the first determination unit 600 determines that the horizontal line screen is to be applied, the horizontal line screen parameter selected by the parameter selection unit 63 is determined as the threshold value to be applied by the threshold processing unit 603. To do.

  When it is determined by the first determination unit 600 that the oblique line screen is to be applied, the parameters for the vertical line screen selected by the parameter selection unit 63 are rearranged according to the dot alignment direction, The threshold processing unit 603 determines the threshold to be applied.

  Next, an example of a processed image in the second embodiment will be described with reference to FIG. The black lines in (1) to (3), that is, some of the black characters, are generated with the combining unit 61 using the dot shift result of FIG. 24, so that the edge portion has a jagged shape. The object information is also converted into a jagged mountain portion, that is, a black pixel is a character object, and a jagged valley portion is converted to a graphic object in accordance with the image.

  (1) is a diagram assuming a geometric correction in which a horizontal line constituting a black character is shifted downward (or up) by 0.5 pixels, and a jagged shape occupies 50% at the top and bottom of the line drawing. (2) is a diagram that assumes geometric correction by shifting 0.25 pixels downward, and the line drawing has a jagged shape with 75% at the top and 25% at the bottom.

  In addition, it does not always have a uniform jagged pattern. When geometric correction with rotation is performed as in (3) or when the line drawing of the input image has an original inclination, the jagged shape in which the ratio changes in a gradation shape. become. In this way, by making the edge portion uneven, it is possible to change the center of gravity of the line in units of less than 1 dot.

  Since (1) to (3) are processed using the object boundary parameters described with reference to FIG. 25, a relatively high frequency uneven pattern is attached to the edge portion. It is unevenness at a level that cannot be visually confirmed with the current printer output resolution, and should appear to be a straight line drawn. Therefore, there is an effect of preventing the rattling of the line due to the image deformation.

  (4) is a processed image of the shaded portion. It is the same that the center of gravity is changed in units of less than 1 dot by making irregularities on the edges of the shaded dots, but since it is processed using the non-object boundary parameters described in FIG. ) And (2) are not regular irregular patterns, but irregular patterns are irregular. Therefore, there is an effect of preventing the occurrence of moire.

  Moire is a pattern that occurs due to interference when patterns with periodicity have different periods. In the present embodiment, the patterns having periodicity are the uneven patterns which one is shaded and the other is here. Since there are various periods of shading, there is also a case where there is a shading having a period different from the period of the concavo-convex pattern, and moire occurs.

  Therefore, in the present embodiment, interference is not generated by destroying the periodicity of the uneven pattern, which is one of the causes of interference. Here, “irregular” is used in the sense of non-periodicity with a loss of periodicity. Further, in the present embodiment, an example in which a parameter group that is regularly arranged or a parameter group that is irregularly arranged is prepared in advance has been described. However, parameters that are sequentially generated using a general random number generation method are described. You may make it use.

  A conventional processed image example will be described with reference to FIG. For example, as in Patent Document 1, conventionally, the foreground / background binarization unit 6 is not provided. Therefore, intermediate density pixels are generated at the boundary between the foreground (black characters) and the background (color background) after geometric correction. Therefore, after the pseudo gradation processing, the intermediate density pixel is replaced with the screen pattern for the character object, and the color background portion is replaced with the screen pattern for the graphic object. Omissions will occur.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and various modifications can be made without departing from the scope of the present invention. For example, each process in the above-described image processing apparatus of the present embodiment can be executed using hardware, software, or a combined configuration of both.

  In the case of executing processing using software, it is possible to install and execute a program in which a processing sequence is recorded in a memory in a computer incorporated in dedicated hardware. Alternatively, the program can be installed and executed on a general-purpose computer capable of executing various processes.

DESCRIPTION OF SYMBOLS 1 Input image acquisition part 2 Rendering part 3 Deviation amount acquisition part 4 Geometric correction parameter setting part 5 Geometric correction part 6 Foreground / background binarization part 7 Pseudo gradation processing part 8 Printer output part 50 Corresponding coordinate point calculation part 51 4 points Extraction unit 52 First object extraction unit 53 Second object extraction unit 54 Interpolation calculation unit 55 Foreground pixel value selection unit 56 Background pixel value selection unit 57 Storage unit 58 Edge determination unit 59 Foreground / background pixel value selection unit 60 Dot alignment Unit 61 Combining Unit 62 Object Boundary Determination Unit 63 Parameter Selection Unit 600 First Determination Unit 601 Second Determination Unit 602 Threshold Determination Unit 603 Threshold Processing Unit

JP 2013-66153 A

Claims (13)

An image processing apparatus that performs geometric correction on input image data,
Geometric correction means for generating a plurality of pixel value corrected image data having different pixel values based on object information of the image data;
A synthesis unit that selects a pixel value to be applied for each pixel from the plurality of pixel value correction image data generated by the geometric correction unit, and generates corrected image synthesis data;
Pseudo gradation processing means for performing pseudo gradation processing on the corrected image composition data generated by the composition means;
An image processing apparatus comprising:   The geometric correction means determines the pixel value of the target coordinate based on the object information of the coordinate point around the target coordinate in the image data corresponding to the predetermined pixel after the geometric correction and the priority for each object information, The image processing apparatus according to claim 1, wherein a plurality of pixel value corrected image data having different values are generated. Edge determination means for acquiring edge information of the pixel of interest in the image data;
The geometric correction means determines the pixel value of the target coordinate based on the object information of the coordinate point around the target coordinate and the priority for each object information when the target coordinate in the image data is an object boundary, When the target coordinate in the image data is a non-object boundary, pixel value corrected image data is generated by determining a pixel value of the target coordinate based on edge information of coordinate points around the target coordinate. The image processing apparatus according to claim 2. The geometric correction means determines the pixel value of the target coordinate based on the object information of the coordinate point around the target coordinate and the coordinate information of the target coordinate, and generates multi-value corrected image data,
Comprising dot shifting means for generating binarized image data obtained by binarizing the pixel values of the multi-value corrected image data generated by the geometric correcting means;
The synthesizing unit generates corrected image synthesized data by selecting a pixel value to be applied for each pixel from the plurality of pixel value corrected image data based on the binarized image data generated by the dot shifting unit. The image processing apparatus according to claim 2, wherein the image processing apparatus is an image processing apparatus.   The geometric correction unit determines a pixel value of the target coordinate based on object information of the image data when the target coordinate in the image data is an object boundary, and the target coordinate in the image data is a non-object boundary. 5. The image processing apparatus according to claim 4, wherein the multi-value corrected image data is generated by determining a pixel value of the target coordinate based on edge information of the image data.   The image processing apparatus according to claim 4, wherein the dot shifting unit includes a first determination unit that determines a screen used for binarization processing.   The image processing apparatus according to claim 4, wherein the dot shift unit includes a second determination unit that determines a dot shift direction in the binarization process.   Characterized by comprising parameter selection means for selecting a parameter defining a screen used in the dot shifting means from a predetermined parameter group based on whether the pixel of interest in the image data is an object boundary or a non-object boundary. The image processing apparatus according to any one of claims 5 to 7.   The parameter selection means, when a pixel of interest in the image data is an object boundary, selects or sequentially generates a parameter defining a screen used in the dot shifting means from a regularly arranged parameter group. The image processing apparatus according to claim 8.   The parameter selection unit selects or sequentially generates a parameter for defining a screen used in the dot shifting unit from an irregularly arranged parameter group when a pixel of interest in the image data is a non-object boundary. The image processing apparatus according to claim 8 or 9. The geometric correction unit corrects distortion of the image data, generates a plurality of object corrected image data having different object information based on the object information of the image data,
The synthesizing unit applies pixel by pixel from the plurality of pixel value corrected image data and the plurality of object corrected image data based on the binarized image data binarized by the dot shifting unit. Select the pixel value and object information to generate the corrected image composition data,
The pseudo gradation processing means determines a screen to be used for pseudo gradation processing to be performed on the corrected image combined data generated by the combining unit based on object information of the corrected image combined data. The image processing apparatus according to any one of claims 2 to 10. Generating a plurality of pixel value corrected image data having different pixel values based on the object information of the input image data and storing them in the storage unit;
Selecting a pixel value to be applied for each pixel from the plurality of pixel value corrected image data stored in the storage unit, generating corrected image composite data, and storing the corrected image composite data in the storage unit;
Performing pseudo gradation processing on the corrected image composite data stored in the storage unit;
An image processing method comprising: Processing for correcting distortion of input image data, generating a plurality of pixel value corrected image data having different pixel values based on object information of the image data, and storing the data in a storage unit;
A process of selecting a pixel value to be applied for each pixel from the plurality of pixel value corrected image data stored in the storage unit, generating corrected image composite data, and storing the corrected image composite data in the storage unit;
A process of performing pseudo gradation processing on the corrected image composite data stored in the storage unit;
A program that causes a computer to execute.

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