JP2019193071A - Information processing apparatus, image processing apparatus, information processing method, and program - Google Patents

Abstract

To improve accuracy of correction on a color image.SOLUTION: An image processing apparatus 1 includes a correction processing unit 102 that corrects luminance in image data of a color image acquired by scanning light on an object to be irradiated. The correction processing unit 102 corrects a pixel value indicating a combination of gradation values of a plurality of color components, on the basis of a position of a pixel in a main scanning direction and a hue of the pixel. The correction processing unit 102 corrects the pixel value on the basis of a three-dimensional lookup table in which the position in the main scanning direction and a pixel value before correction are input values and a pixel value after the correction is an output value.SELECTED DRAWING: Figure 2

Description

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

  In an apparatus such as a scanner having a function of reading an image by scanning an original with light, shading correction for correcting a variation in luminance caused by unevenness in the amount of light of scanning light is performed.

  For example, a light irradiation unit that irradiates scanning light, a reading unit that receives light from the irradiated object and reads a color image of the irradiated object, and a correction coefficient calculated for each position in the main scanning direction with respect to the color image An apparatus is disclosed that includes a correction unit that performs color correction using a color image and a preprocessing unit that performs preprocessing on the basis of an output signal read from a white plate for a color image before color correction is performed ( Patent Document 1).

  The variation in brightness caused by the unevenness in the amount of scanning light varies depending on the position of the scanning light in the main scanning direction. For example, the magnitude (deviation amount) of the luminance variation may be different between the central portion and the end portion in the main scanning range. This is because the amount of scanning light varies depending on the position in the main scanning direction due to the characteristics of the scanning light generation means (light emitting element, lens, mirror, actuator, etc.). Therefore, as in the prior art described above, by using a coefficient calculated for each position in the main scanning direction, it is possible to correct the luminance variation caused by the unevenness in the amount of scanning light.

  Conventional shading correction corrects the white level and black level of each sensor such as a light receiving element. However, the variation in luminance that occurs when reading a color image is not only a deviation caused by unevenness in the amount of light of scanning light. In addition, a deviation caused by a position in the main scanning direction and a hue (a combination of gradation values of a plurality of color components such as RGB) is also included. For example, the R component luminance deviation amount is compared for RGB = (120, 40, 30) pixels (pixels exhibiting dark red) and RGB = (120, 100, 150) pixels (pixels exhibiting bright blue). In this case, even if the R values of both pixels are the same, the deviation amount of the luminance of the R component may be different from each other. This is due to a difference in G value and B value between the two pixels, that is, a difference in hue. Therefore, in the conventional shading correction considering only the luminance value of the single color component, the correction for the color image is insufficient.

  The present invention has been made in view of the above, and an object thereof is to improve the accuracy of correction of a color image.

  In order to solve the above-described problem and achieve the object, one embodiment of the present invention is an information processing apparatus that corrects luminance in image data of a color image acquired by scanning an irradiated object with light. And a correction processing unit that corrects a pixel value indicating a combination of gradation values of a plurality of color components based on the position of the pixel in the main scanning direction and the hue of the pixel.

  According to the present invention, it is possible to improve the accuracy of correction for a color image.

FIG. 1 is a block diagram illustrating a hardware configuration example of the image processing apparatus according to the first embodiment. FIG. 2 is a block diagram illustrating a functional configuration example of the image processing apparatus according to the first embodiment. FIG. 3 is a graph illustrating the deviation amount of the luminance of the R value in the color image. FIG. 4 is a diagram schematically illustrating the function of the 3DLUT according to the first embodiment. FIG. 5 is a diagram illustrating positions in the main scanning direction according to the first embodiment. FIG. 6 is a diagram illustrating a data structure example of a 2DLUT constituting a part of the 3DLUT according to the first embodiment. FIG. 7 is a diagram illustrating a data structure example of the 3DLUT according to the first embodiment. FIG. 8 is a diagram illustrating an example of input values to the 3DLUT when the interpolation processing according to the first embodiment is used. FIG. 9 is a flowchart illustrating a processing example of main scanning color deviation correction according to the first embodiment. FIG. 10 is a block diagram illustrating a functional configuration example of the image processing apparatus according to the second embodiment. FIG. 11 is a diagram illustrating a data structure example of an R value conversion LUT according to the second embodiment. FIG. 12 is a flowchart illustrating a processing example of main scanning color deviation correction according to the second embodiment.

  Hereinafter, embodiments of an information processing device, an image processing device, an information processing method, and a program will be described in detail with reference to the accompanying drawings. The present invention is not limited by the following embodiments, and constituent elements in the following embodiments include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those in the so-called equivalent range. . Various omissions, substitutions, changes, and combinations of the components can be made without departing from the scope of the following embodiments.

(First embodiment)
FIG. 1 is a block diagram illustrating a hardware configuration example of the image processing apparatus 1 according to the first embodiment. The image processing apparatus 1 is an apparatus that processes image data of an image read by scanning an original (irradiated body) with light, and may be, for example, a scanner, a copier, a facsimile machine, a multifunction machine, a commercial printing apparatus, or the like. . The image processing apparatus 1 according to the present embodiment includes a mother board 11 and an image processing board 12 (information processing apparatus).

  The motherboard 11 is an electronic circuit board that performs main control calculation processing of the image processing apparatus 1, and includes a CPU (Central Processing Unit) 21, a memory 22, and an ASIC (Application Specific Integrated Circuit) 23. The CPU 21 executes various functions of the image processing apparatus 1 based on a program stored in the nonvolatile memory 13, control information transmitted from an external device (for example, a PC (Personal Computer) used by a user), and the like. Process. The memory 22 is a storage device that functions as a working area of the CPU 21, and may be, for example, a DRAM (Dynamic Random Access Memory). The ASIC 23 is an integrated circuit for a specific application, and includes an MCH (Memory Controller Hub) (also referred to as a North Bridge), an ICH (I / O Controller Hub) (also referred to as a South Bridge), and the like. The MCH makes it possible to exchange data with the CPU 21, memory 22, PCI (Peripheral Component Interconnect) bus, and the like. The ICH enables data exchange with the nonvolatile memory 13, an external device, and the like.

  The image processing board 12 is an electronic circuit board that performs predetermined image processing on image data acquired by a predetermined image reading mechanism (for example, a mechanism including a document table, a scanning light irradiation device, a photoelectric conversion element, and the like). The image data according to the present embodiment is data that has been subjected to conventional shading correction processing. The image processing includes main scanning color deviation correction that corrects the color deviation of the color image in consideration of the position and hue of the pixel in the main scanning direction. The image processing board 12 can be, for example, an expansion board mainly composed of hard logic such as a field-programmable gate array (FPGA) 31, but is not limited thereto. For example, instead of the image processing boat 12, a processor controlled by a predetermined program, a general-purpose computer, or the like may be used.

  The nonvolatile memory 13 is a storage device that stores a program for controlling the CPU 21 and various data, and may be, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like.

  FIG. 2 is a block diagram illustrating a functional configuration example of the image processing apparatus 1 according to the first embodiment. The image processing apparatus 1 includes a system control unit 101 and a correction processing unit 102.

  The system control unit 101 performs overall control of the image processing apparatus 1 and is realized mainly by the function of the mother board 11 in this embodiment. The system control unit 101 includes an external I / F control unit 111, a parameter setting unit 112, an image data processing unit 113, and a temporary storage unit 114.

  The external I / F control unit 111 receives control information from an external device. The parameter setting unit 112 generates various parameters including information indicating whether to perform correction based on the control information received by the external I / F control unit 111, and transmits the generated parameter to the correction processing unit 102. Further, the parameter setting unit 112 receives the status of the functional unit included in the correction processing unit 102. The image data processing unit 113 stores the image data after the main scanning color deviation correction by the correction processing unit 102 in the nonvolatile memory 13 or the temporary storage unit 114. The temporary storage unit 114 is a buffer that temporarily stores the corrected image data.

  The correction processing unit 102 performs main scanning color deviation correction on the image data after the shading correction. The correction processing unit 102 according to the present embodiment is realized mainly by the function of the image processing board 12. The correction processing unit 102 includes a correction processing control unit 121, an image data reception unit 122, an LUT pixel value acquisition unit 123, a 3DLUT (three-dimensional lookup table) storage unit 124, an interpolation processing unit 125, and an image data transmission unit 126. .

  The correction processing control unit 121 generally controls main scanning color deviation correction performed on image data. The correction processing control unit 121 sets the number of pixels of one line and the number of lines of one frame in the image data based on the parameters received from the parameter setting unit 112. The image data receiving unit 122 receives image data from the image reading mechanism, and based on the number of pixels of one line and the number of lines of one frame set by the correction processing control unit 121, only necessary data is received from the received image data. Is transmitted to the LUT pixel value acquisition unit 123.

  The LUT pixel value acquisition unit 123 extracts the 3DLUT stored in the 3DLUT storage unit 124 based on the parameter transmitted from the parameter setting unit 112, and uses the extracted 3DLUT to extract the main pixel of the correction target pixel. The pixel value after correction corresponding to the scanning direction position and the pixel value (pixel value before correction) of the image data transmitted from the image data receiving unit 122 is acquired.

  The interpolation processing unit 125 uses the corrected pixel value acquired by the LUT pixel value acquisition unit 123 to approximately calculate the corrected pixel value corresponding to the pixel value (gradation value) thinned out in the 3DLUT. Perform the required interpolation process. The interpolation process can be, for example, linear interpolation or polynomial interpolation. Image data including pixel values after interpolation processing is transmitted to the image data transmission unit 126 as image data after main scanning color deviation correction. The image data transmission unit 126 transmits the image data after the main scanning color deviation correction to the image data processing unit 113. The image data processing unit 113 stores the image data after color deviation correction in the main scanning direction in the nonvolatile memory 13 or the temporary storage unit 114.

  Here, a description will be given of luminance variations in pixels that are targets of main scanning color deviation correction. FIG. 3 is a graph illustrating the deviation amount of the luminance of the R value in the color image. In FIG. 3, the horizontal axis indicates the position of the pixel in the main scanning direction, and the vertical axis indicates the luminance deviation amount (difference from the average value) of the R value. FIG. 3 shows a state in which the amount of deviation in luminance differs according to the difference in hue (in this example, red, blue, gray, and yellow). For example, when the main scanning position is 27, the deviation amount when the hue is blue is approximately −1 to 2, but the deviation amount when the hue is red is approximately −5 to −8. . In other words, even when the main scanning direction position is the same, when the hue is different, the deviation amount of the luminance of the R value is different. Therefore, when focusing on R of RGB, main scanning color deviation correction cannot be performed with high accuracy even if gamma correction or the like is performed considering only the R value. The same applies to the G value and the B value.

  As described above, the luminance variation in the color image changes not only according to the position of the pixel in the main scanning direction but also according to the hue. Therefore, in the present embodiment, the accuracy of main scanning color deviation correction in a color image is improved by using a 3DLUT and an interpolation process.

FIG. 4 is a diagram schematically illustrating the function of the 3DLUT according to the first embodiment. The 3DLUT is an LUT for performing a three-dimensional color space conversion. As shown in FIG. 4, by using 3DLUT, input pixel values (Rin, Gin, Bin) are converted into output pixel values (Rout, Gout, Bout). That is, the 3DLUT is a table in which combinations of the three components of the output pixel value are associated with the combinations of the three components of the input pixel value. When the number of input elements to the 3DLUT is Nin, the number of output elements Nout is Nin ^3. Become. For example, when all RGB values of 8 bits (0 to 255) are used as input elements, the combination of RGB values is 256, ³ sets, and 256 ³ sets of conversion data are required. Data is prepared for each position in the main scanning direction.

  FIG. 5 is a diagram illustrating positions in the main scanning direction according to the first embodiment. FIG. 5 shows a state in which the entire scanning area H in the main scanning direction when the original 51 is scanned with light to acquire image data is divided into a plurality of areas H0 to Hm. Each region H0 to Hm has a certain region width Hw. The region width Hw should be set as appropriate according to the use conditions, but can be set to 32 pixels, 128 pixels, or the like. The position in the main scanning direction of the pixel to be corrected corresponds to the regions H0 to Hm to which the pixel belongs. When the X coordinate of the pixel is Px, a region Hn corresponding to the position in the main scanning direction of the pixel can be calculated by the following equation (1).

  Hn = Px / Hw [rounded down to the nearest decimal point] (1)

  FIG. 6 is a diagram illustrating a data structure example of a 2DLUT (two-dimensional lookup table) 61 constituting a part of the 3DLUT according to the first embodiment. The 2DLUT 61 shown in FIG. 6 is a table that prescribes conversion of pixel values when Bin is 0. The 2DLUT 61 of this example converts an input pixel value (Rin, Gin, Bin) = (128, 128, 0) into an output pixel value (Rout, Gout, Bout) = (124, 130, 0), for example. Show. By preparing such a 2DLUT 61 for each of R and G and for each position in the main scanning direction (regions H0 to Hm), the 3DLUT is configured.

  FIG. 7 is a diagram illustrating a data structure example of the 3DLUT 71 according to the first embodiment. The 3DLUT 71 of this example includes a plurality of 2DLUTs 61. A 2DLUT 61 having the number of input elements Nin * 3 is prepared for each main scanning direction position (regions H0 to Hm). For example, when the number of input elements is Nin = 256 (when all combinations of data for 8 bits are prepared), one 3DLUT 71 includes 256 * 3 * (m + 1) 2DLUTs 61.

  As described above, the data size of the 3DLUT 71 tends to increase, but the 3DLUT 71 has a data structure in which RGB gradation values are thinned out, and by using an appropriate interpolation process, the number of input elements Nin (the number of 2DLUT 61) ) And the data size of the 3DLUT 71 can be reduced.

  For example, when the number of input elements is Nin = 17, the gradation of each component of the original pixel value (R, G, B) is 256, and the 8-point interpolation method is used, the input pixel value (Rin, Gin, Bin) is Eight points are prepared and calculated by the following formulas (2) to (4).

Rin = R / 16 [rounded down] (2)
Gin = G / 16 [rounded down] (3)
Bin = B / 16 [rounded down] (4)

  FIG. 8 is a diagram illustrating an example of input values Pn (n = 0 to 7) to the 3DLUT when the interpolation processing according to the first embodiment is used. Each difference dR, dG, dB between the original pixel value (R, G, B) and the input pixel value (Rin, Gin, Bin) is calculated by the following formulas (5) to (7) using a surplus calculation (mod). Calculated.

dR = Rmod16 (5)
dG = Gmod16 (6)
dB = Bmod16 (7)

  Rout of the output pixel values (Rout, Gout, Bout) is calculated by the following equation (8). The same applies to Gout and Bout.

  Rout = (R_P0 * (16-dR) / 16 + R_P1 * dR + R_P2 * (16-dR) / 16 + R_P3 * dR + R_P4 * (16-dR) / 16 + R_P5 * dR + R_P6 * (16-dR) / 16 + R_P7 * dR) / 8 (8) )

  Note that the interval of thinning out gradation values (the number of input elements Nin) is not limited to the above. Increasing the number of input elements Nin increases the data size of the 3DLUT, but can improve the correction accuracy. If the number of input elements Nin is reduced, the correction accuracy is reduced, but the data size of the 3DLUT can be reduced. Further, the number of points used for the interpolation processing is not limited to the above eight points. The correction accuracy can be improved by increasing the score, and the calculation load can be reduced by reducing the score.

  FIG. 9 is a flowchart illustrating a processing example of main scanning color deviation correction according to the first embodiment. First, the correction process control unit 121 acquires pixel information of a pixel to be corrected (S101). The pixel information includes a pixel value (original pixel value (R, G, B)) and a coordinate in the main scanning direction (X coordinate Px).

  The LUT pixel value acquisition unit 123 calculates the main scanning direction position Hn (regions H0 to Hm) from the acquired X coordinate Px, and corresponds to the original pixel value with reference to the 2DLUT 61 corresponding to the calculated main scanning direction position Hn. Eight interpolated pixel values are acquired (S102). The interpolation processing unit 125 performs an interpolation process using the acquired eight interpolation pixel values (S103), and acquires output pixel values (Rout, Gout, Bout).

  The correction process control unit 121 determines whether or not the process has been completed for all the pixels (S104), and when there is a pixel for which the process has not been completed (S104: No), executes the step S101 again. When the processing has been completed for all the pixels (S104: Yes), the shading correction processing is terminated. The main scanning color deviation correction according to the present embodiment is performed on the image data after the shading correction, but the shading correction may be included in the main scanning color deviation correction.

  According to the present embodiment, it is possible to perform main scanning color deviation correction that corrects the color deviation of a color image in consideration of the hue in addition to the position and luminance value of the pixel in the main scanning direction. This makes it possible to correct with high accuracy color deviations that cannot be corrected by only shading correction. In addition, the data size of the 3DLUT can be reduced by using the interpolation process.

  Other embodiments will be described below with reference to the drawings. However, the same or similar portions as those of the first embodiment may be denoted by the same reference numerals and the description thereof may be omitted.

(Second Embodiment)
In the first embodiment, the configuration in which the main scanning color deviation correction is performed using the 3DLUT has been described. As described above, since the data size tends to be large, the 3DLUT is difficult to use when there is a restriction on the memory capacity. Therefore, in the present embodiment, the original pixel value is converted into a hue-considered pixel value that takes into account the influence of the hue by an STU conversion process (conversion calculation process) described later using a preset coefficient. By using a value (pixel value after STU conversion) as an input value to the LUT, shading correction can be performed using a 1DLUT (one-dimensional lookup table) having a small data size.

  FIG. 10 is a block diagram illustrating a functional configuration example of the image processing apparatus 201 according to the second embodiment. The image processing apparatus 201 includes a system control unit 101 and a correction processing unit 202. Since the system control unit 101 is the same as that of the first embodiment, the correction processing unit 202 will be mainly described below.

  Similar to the correction processing unit 102 according to the first embodiment, the correction processing unit 202 performs main scanning color deviation correction on image data after shading correction, and is mainly based on the function of the image processing board 12. Realized. The correction processing unit 202 according to the present embodiment includes a correction processing control unit 211, an image data receiving unit 212, an image data storage unit 213, an STU conversion processing unit 214, an LUT correction value acquisition unit 215, a 1DLUT storage unit 216, and a correction calculation process. A unit 217 and an image data transmission unit 218.

  The correction processing control unit 211 sets the number of pixels per line and the number of lines per frame in the image data based on the parameters received from the parameter setting unit 112. The image data receiving unit 212 receives image data after shading correction from the image reading mechanism, and based on the received image data based on the number of pixels of one line and the number of lines of one frame set by the correction processing control unit 211. Only necessary data is transmitted to the image data storage unit 213. The image data storage unit 213 stores the image data transmitted from the image data reception unit 212, and transmits the image data to the correction calculation processing unit 217 in response to a read request from the correction calculation processing unit 217.

  The STU conversion processing unit 214 performs STU conversion processing on the pixel value (original pixel value) of each pixel of the image data received by the image data receiving unit 212 based on the parameter transmitted from the parameter setting unit 112, Image data including pixel values (hue-considered pixel values) after STU conversion is transmitted to the LUT correction value acquisition unit 215.

  The STU conversion process is a process of converting the original pixel value of the pixel to be corrected into a hue-considered pixel value that takes into account the influence of the hue. For example, the same process as the YUV conversion is performed using a preset coefficient. It can be realized by a method to be performed. The original pixel value is (R, G, B), the hue-considered pixel value is (VR, VG, VB), the coefficient corresponding to VR is (sR, tR, uR), and the coefficient corresponding to VG is (sG, tG, If the coefficients corresponding to uG) and VB are (sB, tB, uB), the following equations (9) to (11) hold.

VR = sR * R + tR * G + uR * B (9)
VG = sG * R + tG * G + uG * B (10)
VB = sB * R + tB * G + uB * B (11)

  The hue-considered pixel values (VR, VG, VB) in this example are normalized so that each value falls within the range of −128 to 128. The coefficients sR, tR, uR, sG, tG, uG, sB, tB, uB are values optimized in advance for each image processing apparatus 201, and are different values for each original pixel value (R, G, B). It is. The setting method of the coefficients sR, tR, uR, sG, tG, uG, sB, tB, uB should be appropriately selected according to the use conditions. For example, the user of the image processing apparatus 201 (administrator, design The original and the printed material obtained by scanning the original with scanning light, and visually comparing the printed material with the coefficients sR, tR, uR, sG, tG, uG, sB, tB, and uB may be set. Further, such a setting method may be automated.

  The LUT correction value acquisition unit 215 extracts the 1DLUT stored in the 1DLUT storage unit 216 based on the parameter transmitted from the parameter setting unit 112, and transmits it from the STU conversion processing unit 214 using the extracted 1DLUT. Correction values (CR, CG, CB) corresponding to the hue consideration pixel values (VR, VG, VB) are acquired.

  FIG. 11 is a diagram illustrating a data structure example of the R value conversion LUT 241 according to the second embodiment. The R value conversion LUT 241 is an LUT that constitutes a part of the 1DLUT, and uses the VR index ID (VR), which is the R value after STU conversion, and the main scanning direction positions H0 to Hm as input values, and corrects R. It is a table which makes CR which is a value an output value. The R value conversion LUT 241 of this example has a data structure in which VR values are thinned out at a predetermined interval, and an index ID (VR) indicating the VR value every 4 is used as an input value. The index ID (VR) can be calculated by the following equation (12), for example.

  ID (VR) = (VR / 4 [rounded to the nearest decimal point)) * 4 (12)

  The 1DLUT storage unit 216 stores a G value conversion LUT and a B value conversion LUT having the same data structure as the R value conversion LUT 241 as described above. That is, the G-value conversion LUT uses the VG index ID (VG), which is the G value after STU conversion, and the main scanning direction positions H0 to Hm as input values, and CG, which is a correction value for G, as output values. B value conversion LUT is a VB index ID (VB) that is a B value after STU conversion and main scanning direction positions H0 to Hm as input values, and CB that is a correction value for B is an output value. It is a table. The 1DLUT of this embodiment includes such an R value conversion LUT 241, a G value conversion LUT, and a B value conversion LUT. The LUT correction value acquisition unit 215 acquires CR, CG, and CB, which are correction values used for main scanning color deviation correction, using the 1DLUT. It should be noted that the data size of 1DLUT can be reduced by using an index obtained by thinning out the values after STU processing (hue-considered pixel values) (VR, VG, VB) as described above. However, the present invention is not limited to this, and a data structure including data for all gradations (256 gradations) may be used.

  The correction calculation processing unit 217 uses the correction values (CR, CG, CB) acquired by the LUT correction value acquisition unit 215 to perform main scanning color deviation correction on the original pixel values (R, G, B) of each pixel. Do. When the correction pixel value (pixel value after main scanning color deviation correction) is (R ′, G ′, B ′), the following equations (13) to (15) are established.

R ′ = R + CR (13)
G ′ = G + CG (14)
B ′ = B + CB (15)

  The image data transmission unit 218 transmits image data including the corrected pixel values (R ′, G ′, B ′) to the image data processing unit 113. The image data processing unit 113 stores the image data including the corrected pixel values (R ′, G ′, B ′), that is, the image data after the main scanning color deviation correction in the nonvolatile memory 13 or the temporary storage unit 114.

  FIG. 12 is a flowchart illustrating a processing example of main scanning color deviation correction according to the second embodiment. First, the correction process control unit 211 acquires pixel information of a pixel to be corrected (S201). The pixel information includes a pixel value (original pixel value (R, G, B)) and a coordinate in the main scanning direction (X coordinate Px).

  The STU conversion processing unit 214 performs STU conversion on the original pixel values (R, G, B) of the pixels to be corrected, and calculates hue-considered pixel values (VR, VG, VB) (S202). The LUT correction value acquisition unit 215 calculates a main scanning direction position Hn (regions H0 to Hm) from the acquired X coordinate Px, calculates the calculated main scanning direction position Hn, and calculated hue-considered pixel values (VR, VG, Correction values (CR, CG, CB) corresponding to (VB) are acquired from the 1DLUT (S203).

  The correction calculation processing unit 217 performs correction calculation processing using the acquired correction values (CR, CG, CB) (S204), and correction pixel values (R ′, G ′, B ′) corrected for main scanning color deviation. ) To get. Thereafter, the correction processing control unit 211 determines whether or not the processing has been completed for all the pixels (S205), and when there is a pixel for which the processing has not been completed (S205: No), step S201 is performed again. When the process is completed for all the pixels (S205: Yes), the main scanning color deviation correction process ends. The main scanning color deviation correction according to the present embodiment is performed on the image data after the shading correction, but the shading correction may be included in the main scanning color deviation correction.

  According to the present embodiment, it is possible to perform main scanning color deviation correction using a 1DLUT having a small data size by using STU conversion that converts luminance value and hue information into one-dimensional information. As a result, it is possible to correct with high accuracy the color deviation of a color image that cannot be corrected only by shading correction with a small memory capacity.

  The program that realizes the functions of the image processing apparatuses 1 and 201 is an installable or executable file that can be read by a computer such as a CD-ROM, memory card, CD-R, and DVD (Digital Versatile Disk). And stored as a computer program product.

  Further, the program may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Further, the program may be provided via a network such as the Internet without being downloaded. Further, the program may be provided by being preinstalled in a ROM or the like. The program may have a module configuration including functions that can be realized by the program among the functional units included in the image processing apparatuses 1 and 201. The functions realized by the program are loaded into the main storage device by reading the program from the storage medium and executing it. That is, the function realized by the program is generated on the main storage device.

  As mentioned above, although embodiment of this invention was described, the said embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1,201 Image processing device 11 Motherboard 12 Image processing board (information processing device)
13 Nonvolatile memory 21 CPU
22 Memory 23 ASIC
31 FPGA
51 Document 61 2DLUT
71 3DLUT
DESCRIPTION OF SYMBOLS 101 System control part 102,202 Correction processing part 111 External I / F control part 112 Parameter setting part 113 Image data processing part 114 Temporary storage part 121 Correction processing control part 122 Image data receiving part 123 LUT Pixel value acquisition part 124 3DLUT storage part 125 Interpolation processing unit 126 Image data transmission unit 211 Correction processing control unit 212 Image data reception unit 213 Image data storage unit 214 STU conversion processing unit 215 LUT correction value acquisition unit 216 1DLUT storage unit 217 Correction calculation processing unit 218 Image data transmission unit 241 R value conversion LUT

JP2015-146493A

Claims (9)

An information processing apparatus that corrects luminance in image data of a color image acquired by scanning an irradiated object with light,
A correction processing unit that corrects a pixel value indicating a combination of gradation values of a plurality of color components based on the position in the main scanning direction of the pixel and the hue of the pixel;
An information processing apparatus comprising: The correction processing unit has the pixel of the pixel based on a three-dimensional lookup table having the main scanning direction position and the pixel value before correction as an input value and a value for correcting the luminance as an output value. Correct pixel values,
The information processing apparatus according to claim 1. The three-dimensional lookup table has a data structure in which the gradation value is thinned out,
The correction processing unit performs an interpolation process for approximately obtaining an output value corresponding to the thinned gradation value based on the output value acquired from the three-dimensional lookup table.
The information processing apparatus according to claim 2. The correction processing unit
By the conversion calculation process using a preset coefficient, the pixel value before correction is converted into a hue-considered pixel value taking into account the influence of the hue,
Correcting the pixel value of the pixel based on a one-dimensional lookup table having the main scanning direction position and the hue-considered pixel value as input values and the value for correcting the luminance as an output value;
The information processing apparatus according to claim 1. The conversion calculation processing includes YUV conversion for converting RGB values into YUV values.
The information processing apparatus according to claim 4. The correction processing unit corrects the image data after shading correction.
The information processing apparatus according to any one of claims 1 to 5. An image reading mechanism for acquiring the image data by causing the irradiated object to scan with light;
The information processing apparatus according to any one of claims 1 to 6,
An image processing apparatus comprising: An information processing method for correcting luminance in image data of a color image acquired by scanning an object with light,
Correcting a pixel value indicating a combination of gradation values of a plurality of color components based on a main scanning direction position of the pixel and a hue of the pixel;
Information processing method including: To a computer that performs processing for correcting the luminance in the image data of a color image obtained by scanning the object with light,
A process of correcting a pixel value indicating a combination of gradation values of a plurality of color components based on the position of the pixel in the main scanning direction and the hue of the pixel;
A program that executes

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