JP2019071537A - Image processing device, control method of the same, and program - Google Patents

Abstract

To provide a mechanism to allow a user to select a color replacement method in double color printing, in response to a printing purpose.SOLUTION: An image processing device, in a case of printing full-color print data with color materials of two colors, receives a user input of designating a conversion method to convert the full-color print data to two-color print data and converts the full-color print data to the two-color print data in accordance with the received conversion method.SELECTED DRAWING: Figure 7

Description

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

  Printing of four CMYK colors (hereinafter referred to as full color printing) is common in the printing industry. Here, C is Cyan, M is Magenta, Y is Yellow, and K is Black. However, in the case of full color printing, the cost is high because color materials for four colors are required. Under such circumstances, two-color printing, which is a process of printing with a reduced number of colors, has attracted attention for cost reduction. The two-color printing is a technology for printing by performing image processing for replacing a color original document with any two different colors (for example, two of Red, Green, Blue, Yellow, Magenta, Cyan, and Black). There are various methods of how to replace a color original with two colors depending on the purpose of printing, such as reduction of toner consumption and maintenance of emphasized color.

  In Patent Document 1, as a method of replacing a color original with a two-color print, a method of converting a chromatic part of Red on an original to Red and converting other portions to Black, a chromatic part on an original A method of converting the achromatic part to Black has been proposed.

JP, 2011-130184, A

  However, the above-described prior art has the problems described below. For example, in the above-mentioned prior art, since the color and method for replacing a color document are automatically determined by the type and finish type of the document, the method for replacing the color document is limited. On the other hand, there is a demand for two-color printing in accordance with various printing purposes.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mechanism that allows a user to select a color replacement method in two-color printing according to the printing purpose.

  The present invention is an image processing apparatus, which accepts a user input specifying a conversion method for converting full color print data into two color print data when full color print data is printed with two color materials. It is characterized by comprising: reception means; and conversion means for converting the full color print data into two-color print data according to the conversion method received by the reception means.

  According to the present invention, it is possible to select a method of replacing colors in two-color printing in accordance with the printing purpose of the user.

FIG. 2 is a block diagram for explaining the functional configuration of the image processing apparatus according to the embodiment; FIG. 7 is a UI image diagram of selection of two-colors according to an embodiment. FIG. 6 is a UI image diagram of color selection according to one embodiment. 6 is an exemplary process flowchart of a two-color conversion table generation unit according to an embodiment. The figure which shows typically the color conversion table which the 2 color conversion table production | generation part which concerns on one Embodiment produces | generates. FIG. 6 is a view showing an example of an output sample at the time of two-color printing according to an embodiment. 6 is a flowchart illustrating the flow of processing of a color conversion unit according to an embodiment. FIG. 7 is a selected UI image view of a two-color mode according to an embodiment. 8 is a flowchart for describing the details of color conversion processing in mode A in the processing of the color conversion unit according to an embodiment. 8 is a flowchart for describing the details of color conversion processing in mode B in the processing of the color conversion unit according to an embodiment. FIG. 6 is a diagram illustrating hues on an a * b * plane in an L * a * b * color space. The figure which shows an example of the chromatic judgment area | region on the a * b * plane of L * a * b * space. The figure which shows the determination result output table which concerns on one Embodiment. FIG. 1 is a block diagram showing the configuration of a system of an image processing apparatus according to an embodiment. FIG. 7 is a view showing an example of a threshold value table of boundary pixel determination of hue and saturation according to one embodiment.

  One embodiment of the present invention is shown below. The specific embodiments described below will help to understand various concepts such as the superordinate, middle and sub-concepts of the present invention. Further, the technical scope of the present invention is established by the scope of the claims, and is not limited by the following individual embodiments.

First Embodiment
<Configuration of Image Processing Device>
Hereinafter, a first embodiment of the present invention will be described. The image processing apparatus according to the present embodiment will be described as an MFP (Multifunction Peripheral) 10 having an image processing apparatus (image processing unit) 100, a scanner 110, a print engine 108, a display unit, and an operation unit (UI 111). However, the present image processing apparatus may have any form as long as it has a print function, a display unit, and an operation unit. In the following, when the term “image processing apparatus” is used to indicate the entire image processing system such as an MFP, it is simply described as “image processing apparatus” and an apparatus specialized for image processing only (image processing unit) In the case of using the image processing apparatus 100, the image processing apparatus 100 is described.

  First, an example of the system configuration of the image processing apparatus (MFP 10) according to the present embodiment will be described with reference to FIG. The image processing apparatus according to the present embodiment is applied to a laser beam printer or an ink jet printer, and configures a system by being connected to a host computer (not shown). In the present image processing apparatus, the MFP 10, which is one of the devices, is connected via an input unit 1404 serving as a window for data input from the outside of the MFP 10 and a printer controller of a host computer (not shown). The MFP 10 includes a CPU 1401, a RAM 1402, a ROM 1403, an input unit 1404, a print unit I / F (interface) 1405, an MC (memory controller) 1406, a print engine 108, a display / operation unit 1409, and a storage device 112. These units can transmit and receive information via the system bus 1407.

  The MFP 10 controls each device connected to the system bus 1407 by the CPU 1401 executing a control program stored in the ROM 1403 or the storage device (external memory) 112. The RAM 1402 is used as a main storage area of the CPU 1401 as an output information expansion area or the like. The storage device 112 supplies font data, form data, an emulation program, and the like via the memory controller (MC) 1406.

  The CPU 1401 inputs image data via the input unit 1404. The input unit 1404 corresponds to a scanner 110 as a reading unit to be described later, and inputs image data read from a document. The input unit 1404 can also input image data by receiving image data from an external device connected via a network. The CPU 1401 also outputs an image signal to a print engine (print unit) 108 connected via the print unit I / F 1405.

  A display / operation unit 1409 functions as a reception unit, includes switches and display devices for setting the operating environment of the MFP 10, and is used to operate environment data and user information stored in the RAM 1402. The display and operation unit 1409 corresponds to the UI (user interface) 111 of FIG. 1 described later.

  Subsequently, an example of a functional configuration of the image processing apparatus 100 according to the present embodiment will be described with reference to FIG. As described above, the MFP 10 according to this embodiment includes the print engine 108, the image processing apparatus 100, the scanner 110, a UI (User Interface) 111, and a storage device (storage unit) 112. The MFP 10 is also connected to a computer 109 which is an external device. The image processing apparatus 100 further includes an image data acquisition unit 101, a color determination unit 102, a two-color conversion table generation unit 103, a two-color conversion table storage unit 104, a color conversion unit 105, a gamma correction unit 106, and an image forming unit 107. Equipped with Further, in order to print the image data output from the image forming unit 107, the print engine 108 is connected.

  Each function described below is realized by, for example, the CPU 1401 developing a program stored in the ROM 1403 into the RAM 1402 and executing the program. A RAM 1402 is used as a storage or acquisition destination of data required for each function.

  The image data acquisition unit 101 renders print data such as PDL data received from the computer 109 connected to the image processing apparatus 100 under the control of the CPU 1401 and generates RGB image data in the bitmap format and attribute information. . Attribute information is information that distinguishes in object units such as graphics (graphics), text (characters), images (photographs), and the like. Under control of the CPU 1401, the image data acquisition unit 101 stores the generated RGB image data and attribute information in the RAM 1402. When a document is read by the scanner 110, the image data acquisition unit 101 stores, in the RAM 1402, RGB image data generated from the read document. In the present embodiment, RGB image data is described as an example, but any image data may be used as long as the image data has a color space that can be converted to the LCH color space described later.

  The color determination unit 102 reads the setting value set by the display / operation unit 1409 stored in the RAM 1402 under control of the CPU 1401 and stores the read setting value in the RAM 1402. FIG. 2 shows an example of the UI of the screen 201 for setting the number of colors displayed on the display and operation unit 1409. The screen 201 is configured to include a full color 202, a two-color color 203, and an OK button 204. When full color printing using CMYK color materials is performed, full color printing is set by selecting the full color 202 and operating the OK button 204. On the other hand, when performing two-color printing, two-color printing is set by selecting the two-color color 203 and operating the OK button 204.

  When the two-color color 203 is selected or when the OK button 204 is operated in a state where the two-color color 203 is selected, the display and operation unit 1409 controls the UI menu 301 shown in FIG. indicate. In the UI menu 301 shown in FIG. 3, buttons 302 to 307 for selecting a color to be combined with black (designated color) in two-color printing and an OK button 308 are displayed so as to be selectable. For example, it is possible to select an arbitrary color from each color of red (red) 302, green (green) 303, blue (blue) 304, cyan (cyan) 305, magenta (magenta) 306, and yellow (yellow) 307. it can. A designated color can be set by selecting one of the buttons 302 to 307 and operating the OK button 308. The color determination unit 102 stores the designated color selected from the UI menu 301 shown in FIG. Although the case where six colors can be selected will be described in the present embodiment, it is not limited to six colors. The set value may be designated in advance, or may be set when printing is performed.

  It returns to the explanation of FIG. The two-color conversion table generation unit 103 acquires the designated color set by the color determination unit 102 from the RAM 1402 under the control of the CPU 1401. The two-color conversion table generation unit 103 generates a two-color conversion table (for example, in the form of a look-up table) for converting RGB image data into CMYK image data for two-color printing based on the designated color. The generated two-color conversion table is stored in the two-color conversion table holding unit 104. Details of generation of the two-color conversion table will be described later.

  The color conversion unit 105 acquires RGB image data generated by the image data acquisition unit 101 from the RAM 1402 under the control of the CPU 1401, and acquires a two-color conversion table from the two-color conversion table storage unit 104. Furthermore, the color conversion unit 105 performs color conversion of RGB image data into CMYK image data for two-color printing using the acquired two-color conversion table. CMYK image data for two-color printing is stored in the RAM 1402. In addition, as a color conversion method, any known color conversion method such as tetrahedron interpolation or cubic interpolation can be used. Details of the processing of the color conversion unit 105 will be described later.

  The gamma correction unit 106 acquires CMYK image data converted by the color conversion unit 105 from the RAM 1402 under the control of the CPU 1401 and applies correction processing for maintaining the gradation characteristics in the print engine 108 to the acquired CMYK image data . The CMYK image data subjected to the correction processing is stored in the RAM 1402.

  The image forming unit 107 acquires CMYK image data corrected by the gamma correction unit 106 from the RAM 1402 under control of the CPU 1401 and converts the CMYK image data into N (integer) bit halftone image data suitable for the print engine 108. The CPU 1401 controls sending halftone image data to the print engine 108. Although various methods such as a density pattern method, a systematic dither method, and an error diffusion method have been proposed as halftone processing, any method may be adopted in this embodiment. Although the print engine 108 is described below as an engine using CMYK toner, it is needless to say that an engine using CMYK ink may be used.

<Color conversion table generation process>
Next, the processing procedure of the two-color conversion table generation unit 103 according to the present embodiment will be described with reference to FIG. Each process of the two-color conversion table generation unit 103 is realized by expanding a program stored in the ROM 1403 into the RAM 1402 and executing the program under the control of the CPU 1401. Data generated in each process can be held in the RAM 1402 and acquired from the RAM 1402.

  In step S401, the two-color conversion table generation unit 103 reads and acquires, from the storage device 112, a full-color color conversion table for converting RGB image data used in full-color printing into CMYK image data. The color conversion table for full color defines a cube of a three-dimensional color space defined by RGB signals, and as shown in FIG. 5, in the cube of the three-dimensional color space according to the value of each 8-bit data of RGB. Coordinates can be defined. The eight vertices of the cube indicate Red (R), Green (G), Blue (B), Yellow (Y), Magenta (M), Cyan (C), Black (K), and White (W). In addition, the color conversion table has, for example, 16 × 16 × 16 grid points defined by RGB values of input data, and L * a * b * values (502) or CMYK values (503) corresponding to the grid points. Are stored as table data. That is, the table 502 is a table for converting RGB values to L * a * b * values, and the table 503 is a table for converting RGB values to CMYK values. For example, in the table 503, CMYK values (0, 255, 255, 0) are stored as table data corresponding to RGB values (255, 0, 0).

  It returns to the explanation of FIG. Next, in S402, the two-color conversion table generation unit 103 causes the color determination unit 102 to read and acquire the designated color stored in the RAM 1402 from the RAM 1402. Subsequently, in step S403, the two-color conversion table generation unit 103 converts the full-color CMYK values stored in the full-color color conversion table read in step S401 for two-color printing according to the designated color read in step S402. Convert to CMYK values. The two-color conversion table generation unit 103 sequentially stores the conversion result in the RAM 1402. For example, if the CMYK values for full color have 16.times.16.times.16 grid points, they are converted into CMY values and K values for a total of 4096 two-color prints. Specifically, matrix operation is performed on the CMYK values corresponding to each lattice point. For example, when Red is set in a designated color, the CMY values stored in the color conversion table are converted into M values and Y values that are color values constituting Red using matrix operations like Equation 1 below. The K value is converted to be output as it is. In the following, formulas in other designated colors are also described.

  Similar to Equation (7), other intermediate colors (pink, purple, etc.) can be converted in the same manner.

  Next, in step S404, the 2-color conversion table generation unit 103 reads out the CMYK values for 2-color printing converted in step S403 from the RAM 1402, generates a 2-color conversion table, and generates the 2-color conversion table as a 2-color conversion table. Write to the holding unit 104 and end the process.

<Color conversion processing>
Next, the process flow of the color conversion unit 105 will be described using the flowchart of FIG. 7. Each process of the color conversion unit 105 is realized by expanding a program stored in the ROM 1403 into the RAM 1402 and executing the program under the control of the CPU 1401. Data generated in each process can be held in the RAM 1402 and acquired from the RAM 1402.

  In step S701, the color conversion unit 105 acquires the set designated color stored in the RAM 1402 in the color determination unit 102 from the RAM 1402. Subsequently, in step S702, the color conversion unit 105 acquires the image data stored in the RAM 1402 by the image data acquisition unit 101 from the RAM 1402.

  Next, in step S703, the color conversion unit 105 converts the image data acquired in step S702 from RGB to LCH space. The converted image data is stored in the RAM 1402. The conversion to the LCH space is performed by once converting the RGB color space to the L * a * b * space and further converting to the LCH space. Here, the L * a * b * space is a color space developed by the CIE (International Commission on Illumination) as a device-independent three-dimensional color space. L * indicates the brightness, a * indicates the degree of red, and b * indicates the degree of yellow. It becomes achromatic when a * and b * approach 0, and becomes brighter as the values of a * and b * deviate from 0. Also, LCH space is a device-independent three-dimensional color space, similar to L * a * b * space. L represents lightness, C represents saturation, and H represents hue. The value of H is represented by an angle of 0 to 360.

  Here, a method of converting RGB image data into L * a * b * space will be specifically described. In the conversion to the L * a * b * space, the RGB values of each pixel of the RGB image data are converted into L * a * b * values pixel by pixel. Conversion of each pixel to an L * a * b * value is performed by acquiring an RGB → L * a * b * conversion table 502 as shown at 502 in FIG. 5 from the storage device 112 and performing an interpolation operation. The RGB → L * a * b * conversion table 502 defines a cube of a three-dimensional color space defined by RGB signals. As shown in FIG. 5, in the table 502, the coordinates in the cube (501) of the three-dimensional color space can be determined in accordance with the value of each 8-bit data (0 to 255) of RGB. The eight vertices of the cube indicate Red, Green, Blue, Yellow, Magenta, Cyan, Black, White. Also, the RGB → L * a * b * conversion table 502 has, for example, 9 × 9 × 9 grid points defined by the RGB values of the input data, and L * a * b * values corresponding to these grid points are It is stored as table data. For example, in the table 502 of FIG. 5, L * a * b * values (44.01, 61. 37, 39. 68) are stored as table data corresponding to RGB values (255, 0, 0).

In the interpolation calculation, when a value not defined in the calculation table is input, interpolation is performed using a value defined in the calculation table close to the input value. One method of interpolation calculation is called tetrahedron interpolation. In tetrahedral interpolation, interpolation calculation is performed using values defined in four calculation tables close to the input value. In this process, the input is RGB values of each pixel of RGB image data, and the operation table is an RGB → L * a * b * conversion table 502 to perform tetrahedron interpolation operation to obtain L * a of each pixel. Calculate the * b * value. Although tetrahedral interpolation is used for conversion in the present embodiment, the present invention is not limited to this, and any method may be used as long as RGB space can be converted to L * a * b * space, such as conversion by an arithmetic expression. Good. Subsequently, the RGB image data converted into the L * a * b * space is converted into the LCH space. Since L * of L * a * b * and L of LCH are the same, they are used as they are. The value of C (saturation) is determined by the following Equation 8 and Equation 9.
C = sqrt (a * ^ 2 + b * ^ 2) formula 8
Here, sqrt represents a square root calculation, and ^ represents a power calculation. Further, the value of H (hue) is obtained by the following equation.
H = arctan (b * / a *) x (180 / PI)
H = H (when H> 0)
H = H + 360 (in the case of H <0) Formula 9
Here, arctan represents the calculation of arctangent, and PI represents pi of π. H is expressed by an angle of 0 ° to 360 °. The color space of RGB image data is converted by performing these processes on all the pixels of RGB image data.

  Return to the predication of FIG. Next, in step S704, the color conversion unit 105 reads the mode setting value displayed on the display and operation unit 1409 from the RAM 1402. FIG. 8 shows an example of a UI menu 800 of mode setting values displayed on the display and operation unit 1409 (UI) of the image processing apparatus. In the UI menu 800, one of two types of mode A 801 and mode B 802 is displayed so as to be selectable as a method of replacing colors in two-color printing, and an OK button 803 is displayed so as to be selectable. When two-color color is selected in the two-color color selection UI menu 201 shown in FIG. 2, the display / operation unit 1409 displays the color selection UI 301 in FIG. 3. When the color selection is displayed, the UI menu 800 shown in FIG. 8 is subsequently displayed on the display / operation unit 1409 and can be selected.

  When the mode A 801 is selected, the achromatic part is replaced with an achromatic color (for example, gray) and the chromatic part is replaced with the designated color acquired in S 701 among the image data acquired in S 702. On the other hand, when mode B 802 is selected, the portion of the hue of the designated color acquired in S 701 that is the chromatic part of the image data acquired in S 702 is replaced with the designated color, and other chromatic parts and achromatic parts Is replaced by gray. The setting value may be selected by the user in advance, or may be selected by the user when a print job or the like is received and two-color printing is performed. Also, the mode is not limited to the two types of mode A and mode B, and other modes may be selected.

  Next, in step S705, the color conversion unit 105 determines which of the mode A and the mode B the color replacement method for two-color printing acquired in step S704 is, and if mode A, the process of step S706 is performed. . On the other hand, if the mode is mode B, the process of S 707 is performed. In step S706, the color conversion unit 105 converts the image data acquired in step S702 into CMYK values using the mode A color conversion method. The converted image data is stored in the RAM 1402. As a result of the process of S706, of the image data acquired in S702, the achromatic part performs gray image processing, and the chromatic part performs image processing to replace the designated color (for example, CMYRGB or the like) acquired in S701. Details of the image processing will be described later. FIG. 6 shows the processing result of color conversion when the processing of S706 is executed. For example, when the document 600 is configured of Yellow, Black, and Red, and Yellow is set as the designated color in S701, the two-color sample (1) 601 is printed. This is because the portions of yellow and red, which are chromatic colors, are both converted to the designated color Yellow, and the portions of Black are converted to Black.

  On the other hand, in step S 707, the color conversion unit 105 converts the image data acquired in step S 702 into CMYK values using the mode B color conversion method. The converted image data is stored in the RAM 1402. As a result of the processing of S 707, among the image data acquired in S 702, the chromatic color part and the designated color part acquired in S 701 are converted into the designated color, and the other chromatic parts and achromatic parts execute image processing to be replaced by gray. Do. An example of the processing result of the two-color conversion in S707 is shown in FIG. For example, when the document 600 is configured of Yellow, Black, and Red, and Yellow is set as the designated color in S701, the two-color sample (2) 602 is printed. This is because the yellow range on the document which is the designated color is converted to the designated color Yellow, and the red and black portions of the other document are transformed to Black. Details of the image processing will be described later.

  After that, when the image data is stored in the RAM 1402 in S706 or S707 in S708, the color converter 105 outputs an image to start the processing of the gamma correction unit 106 under the control of the CPU 1401.

<Color conversion processing of mode A>
Next, details of the process (S706) of performing color conversion in mode A in the process of the color conversion unit 105 will be described using the flowchart of FIG. Each process of the color conversion unit 105 is realized by expanding a program stored in the ROM 1403 into the RAM 1402 and executing the program under the control of the CPU 1401. Data generated in each process can be held in the RAM 1402 and acquired from the RAM 1402.

  In step S901, the color conversion unit 105 acquires the image data converted into the LCH space in step S703 from the RAM 1402, and is a chromatic color or an achromatic color using the value of C (saturation) among the pixel values of the target pixel. Determine if it is. The determination as to whether the color is chromatic or achromatic is performed by acquiring a threshold previously stored in the storage device 112 and comparing the threshold with the value of C (saturation). For example, when the threshold value is 20, if C (saturation) is less than 20, it is determined to be achromatic, and if it is 20 or more, it is determined to be chromatic. In the present embodiment, although the threshold value is a value held in advance, it may be set dynamically according to the configuration of the input image, or may be selected from the UI or the like. Further, in the present embodiment, the determination result is stored in the RAM 1402 as a flag. The color conversion unit 105 generates a color determination flag according to the determination result, and sets the color determination flag to 0 if it is achromatic, and to 1 if it is chromatic. Of course, any form may be used as long as the information as to whether it is a chromatic color or an achromatic color can be stored in the RAM 1402.

  Next, in step S902, the color conversion unit 105 acquires the image data stored in the RAM 1402 in step S702 from the RAM 1402, and determines whether to convert the pixel at the same coordinates as the target pixel in step S901 into a specified color or achromatic. judge. Further, according to the present embodiment, the color conversion unit 105 stores the determination result as a flag in the RAM 1402. The color conversion unit 105 acquires the chromatic / achromatic determination result generated in S901 from the RAM 1402, and sets the designated color determination flag to 1 if the color determination flag is 1, and determines the specified color if the color determination flag is 0. Set the flag to 0. The specified color determination flag generated is stored in the RAM 1402. Of course, any form may be used as long as information on whether the designated color conversion or the achromatic conversion can be stored in the RAM 1402.

  Next, in step S903, the color conversion unit 105 acquires the designated color determination flag generated in step S902 from the RAM 1402, and determines whether the designated color determination flag is 1 or not. Do. On the other hand, if the specified color determination flag is 0, the process of S905 is performed.

  In step S904, the color conversion unit 105 replaces the target pixel of the image data handled in step S902 with the designated color acquired in step S701, and stores the specified color in the RAM 1402. As a flow of conversion to a designated color, first, using the color conversion table for two colors stored in the two-color conversion table storage unit 104, RGB values of pixels are converted to CMYK values.

  On the other hand, in step S905, the color conversion unit 105 replaces the target pixel of the image data handled in step S902 with gray. The color conversion unit 105 converts the RGB values of the pixels of the image data acquired in S702 into an achromatic color, and stores the achromatic color in the RAM 1402. In the flow of conversion to achromatic color, RGB values of pixels are converted into CMYK values using the full-color color conversion table stored in the two-color conversion table storage unit 104. Subsequently, full-color CMYK values are converted to CMYK values constituting an achromatic color using an arithmetic expression. The conversion to CMYK values using the full color color conversion table is the same as that in step S904, and thus the description thereof is omitted. Subsequently, full color CMYK values calculated by tetrahedron interpolation calculation using a full color color conversion table are converted into CMYK values constituting an achromatic color using an arithmetic expression. The calculation is performed using the following matrix equation (Equation 10).

  In this embodiment, conversion from RGB values to CMYK values constituting an achromatic color is performed using a color conversion table and a matrix operation, but if RGB values can be converted to achromatic color CMYK values, how is it? Methods may be used.

  Next, in step S906, the color conversion unit 105 determines whether all the pixels of the RGB image data acquired from the RAM 1402 in step S702 have been processed. The determination method may be made by providing a flag indicating that each pixel has been processed, or the total number of pixels is held in the RAM 1402 at the time of image data acquisition, and it is determined whether the processing has been repeated for the total number of pixels. May be If all the pixels have not been processed, the process returns to S901. On the other hand, if all pixels have been processed, this flowchart ends.

<Color conversion processing of mode B>
Next, details of the process (S 707) of performing color conversion in mode B in the process of the color conversion unit 105 will be described using the flowchart of FIG. 10. Each process of the color conversion unit 105 is realized by expanding a program stored in the ROM 1403 into the RAM 1402 and executing the program under the control of the CPU 1401. Data generated in each process can be held in the RAM 1402 and acquired from the RAM 1402.

  In step S1001, the color conversion unit 105 determines whether the color is chromatic or achromatic using the value of C (saturation) of the target pixel of the image data stored in the RAM 1402 in step S703. Since this process is the same as that of S901 mentioned above, explanation is omitted.

  Next, in step S1002, the color conversion unit 105 determines whether the target pixel is within the hue range of the designated color based on the designated color acquired in step S701 and the hue range value stored in advance in the storage device 112. The hue range value is a value that represents the hue range of each of the designated colors C, M, Y, R, G, and B.

  FIG. 11 is a diagram showing the hue on the a * b * plane in the L * a * b * color space. The horizontal axis shows the a * value, and the vertical axis shows the b * value. For example, a color having a hue in the range of 1101 to 1102 is expressed as Red, and a color having a hue in the range of 1102 to 1103 is expressed as Yellow. The hue range value uses a predetermined value corresponding to each of C, M, Y, R, G, and B. The hue range value has two values, a lower limit value and an upper limit value. For example, in the range of Red in FIG. 11, the hue range lower limit is a hue value (for example, 10 °) corresponding to 1101, and the hue range upper limit is a hue value (for example, 80 °) corresponding to 1102. Therefore, when the designated color is Red, the lower limit value of the hue range is 10 ° and the upper limit value of the hue range is 80 ° as the hue range value. However, as in the case of Magenta in FIG. 11, in the case of the hue range including the a * axis which is 0 °, the hue range is between 0 ° and the hue lower limit 1101 and between the hue upper limit 1106 and 360 °. .

  Although the hue range value is a predetermined value in the present embodiment, it may be set dynamically according to the characteristics of the image processing apparatus, or may be selected from a UI or the like. For example, when the designated color is Red, the hue range lower limit is 10 ° and the hue range upper limit is 80 °. Therefore, the value of H (hue) is 10 ° or more. If it is less than 80 °, it is determined that it is within the hue range, otherwise it is determined that it is outside the hue range. In the present embodiment, the determination result is stored in the RAM 1402 as a flag. A hue determination flag indicating whether or not it is within the hue range is generated according to the determination result, the hue determination flag is set to 1 if it is within the hue range, and the hue determination flag is set to 0 if it is outside the hue range. Do. Of course, any form may be used as long as the information inside and outside the hue range can be stored in the RAM 1402.

  It returns to the explanation of FIG. Next, in step S1003, the color conversion unit 105 acquires the image data converted in step S703 from the RAM 1402, determines the presence or absence of a hue saturation pixel, and generates information on the determination result. In the present embodiment, the generated determination result is held in the RAM 1402 as a flag. If it is determined that the hue / saturation boundary pixel does not satisfy the above condition, the flag is set to 0, and if it is satisfied, the flag is set to 1. Of course, any form may be used as long as information on the determination result can be stored in the RAM 1402.

  With the presence / absence determination of the hue / saturation boundary pixel, it is determined whether the pixel of the image data is present near the boundary where the determination result of the inside / outside determination of the hue range is switched or near the boundary where the determination result of the hue determination is switched. It is a determination as to whether a pixel satisfies a predetermined condition when it is present. Details of this process will be described later.

  Next, in step S1004, the color conversion unit 105 determines whether to convert the pixel of interest of the image data acquired in step S702 into a designated color or into an achromatic color. FIG. 13 shows which of the designated color and the achromatic color is to be converted in the combination of the values of the flags. The color determination flag generated in S1001 and held in the storage device 112 corresponds to 1301. The hue determination flag generated in S1002 and held in the storage device 112 corresponds to 1302. The hue / saturation boundary pixel determination flag generated in S1003 and held in the storage device 112 corresponds to 1303. A table (determination result output table) which has the value of each determination flag as an input and the converted color 1304 of FIG. 13 as an output is stored in advance in the storage device 112. For the conversion color 1304, for example, values are associated such that the designated color is 1, and the achromatic color is 0, and the value is set as an output value. The color determination unit 102 acquires a determination result output table from the storage device 112, and uses the table to input the values of the color determination flag, the hue determination flag, and the boundary pixel determination flag of hue saturation, as a designated color or achromatic color Output a value (for example, 1 or 0) corresponding to Note that the numbers in FIG. 1 and No. 1 Since the combination of 7 does not exist in the present processing, it is not applicable.

  Next, in step S1005, the color conversion unit 105 acquires the specified color determination flag generated in step S1004 from the RAM 1402, determines whether it is 1 or not, and performs 1 in the case of 1. On the other hand, when the designated color determination flag is 0, the processing of S1007 is performed. The processing in step S1006 is the same as that in step S904, and thus the description thereof is omitted. On the other hand, the processing in step S1007 is the same as that in step S905, and thus the description will be omitted.

  Finally, in step S1008, the color conversion unit 105 determines whether all the pixels of the RGB image data acquired in step S702 have been processed. The determination as to whether all pixels have been processed adds a flag indicating whether each pixel has been processed, and determines whether the flag of all pixels has been processed. Note that when image data is acquired in S702, the total number of pixels may be held in the RAM 1402, and it may be determined whether the processing has been repeated for the total number of pixels. If all the pixels have not been processed, the process returns to step S1001. On the other hand, if all pixels have been processed, this flowchart ends.

<Boundary pixel determination>
Next, the detailed process in S1003 of FIG. 10 will be described. In step S1003, the color conversion unit 105 acquires the image data converted in step S703 from the RAM 1402 under the control of the CPU 1401, determines the presence or absence of a hue saturation pixel, and generates information on the determination result. The determination result is stored in the RAM 1402 as a flag. For example, when the designated color is Red, the area enclosed by the solid line in FIG. 12 is within the hue range of Red and a chromatic part. Among the sides of this area, 1208, 1209, and 1210 excluding the outer periphery become the boundary part of the determination result. It is determined whether the target pixel of the image data converted to LCH in S703 is near the boundary. Whether or not the pixel exists near the boundary is determined based on whether the H (hue) and C (saturation) of the pixel are within a predetermined range. In the present embodiment, the predetermined range is a range that satisfies any one of the following conditions.
· The pixel “C (saturation) is within the chromatic range” and “H (hue) is within ± 5 ° centering on the lower limit of the hue range or ± 5 ° centering on the upper limit of the hue range Within range
・ The pixel “C (saturation) is within ± 5 range centered on the chromatic achromatic judgment boundary (1210)” and “H (hue) is within the hue range of the specified color”
In order to determine whether the above conditions are satisfied, each value corresponding to the designated color, which is stored in advance in the form of a table as shown in FIG. For example, the case where the designated color is Red will be described. Lower limit value [10], upper limit value [80], lower limit boundary range (lower limit value) [5], upper limit boundary range (lower limit value) [15], lower limit boundary range (upper limit value) of the row of R in the table in FIG. [75] Acquire the upper limit boundary range (upper limit value) [85]. Then, the value is compared with the value of the target pixel of the image data converted to LCH in S703, and when it is within the range of the above-mentioned value, it is determined to be the boundary pixel of hue and saturation.

  For example, in the case where the designated color is Red, in the case where “C (saturation) is 20 or more” and “H (hue) is in the range of 5 ° to 15 ° or in the range of 75 ° to 85 °” It determines that it exists. Alternatively, in the case where “C (saturation) is 15 to 25” and “H (hue) is in the range of 10 ° to 80 °” of the pixel, it is determined that the pixel is near the boundary. In this embodiment, C (saturation) is ± 5 and H (hue) is ± 5 °, but may be set dynamically according to the characteristics of the image processing apparatus, or selected from the UI or the like. It may be possible.

  As described above, when printing full-color print data with two-color colorants, the image processing apparatus according to the present embodiment specifies a conversion method for converting the full-color print data into two-color print data. Accept user input. Furthermore, the image processing apparatus converts full-color print data into two-color print data according to the received conversion method. As described above, a UI is provided which allows the user to select the replacement method of the color of the two-color print, and the two-color print according to the individual printing purpose by performing the two-color printing according to the set replacement method of the color. It becomes possible to select the replacement method of by user input. That is, it is possible to select a method of replacing colors in two-color printing in accordance with the printing purpose of the user.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the printing (printing) function provided by the MFP 10 is described on the premise of printing in full color or printing in two colors. However, the MFP 10 includes the scanner 110 and also includes a copy function. That is, the present invention selects the mode (mode A and mode B) of the color conversion method according to the user input when copying in two colors based on a full color document when the copying function is used. Can be applied to the configuration. Alternatively, the mode A 801 or the mode B 802 selected by the user via the UI menu 800 in FIG. 8 may be collectively reflected on a plurality of functions provided by the MFP 10, for example, the print function and the copy function. This makes it possible to prevent the method of color conversion from being different for each service, and to prevent printed matter (output result) that the user does not intend.

<Other Embodiments>
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

  10: MFP, 100: image processing apparatus, 101: image data acquisition unit, 102: color determination unit, 103: two-color conversion table generation unit, 104: two-color conversion table storage unit, 105: color conversion unit, 106: gamma Correction unit 107: Image forming unit 108: Print engine 109: Computer 110: Scanner 111: UI 112: Storage device

Claims (12)

An image processing apparatus,
Reception means for receiving a user input specifying a conversion method for converting full color print data into two color print data when printing full color print data with two color materials;
An image processing apparatus comprising: conversion means for converting the full color print data into two color print data according to the conversion method received by the reception means.   The receiving unit further receives, by user input, whether full-color printing or printing with two-color colorants is received, and one of the two colors is received when user input for printing with the two-color colorants is received. The image processing apparatus according to claim 1, wherein a screen for selecting one of the designated colors is displayed on the display unit.   The receiving unit converts, as the conversion method, a chromatic color part of an image corresponding to full-color print data into a designated color input by a user, and converts the achromatic color part into an achromatic color; In the display unit, a screen for selecting a second conversion method of converting a portion corresponding to the designated color in the chromatic portion into a designated color and converting the other chromatic portion and the achromatic portion into achromatic color The image processing apparatus according to claim 2, wherein the image is displayed.   The image processing apparatus according to claim 3, wherein the conversion method received by the receiving unit is collectively reflected on a plurality of functions provided by the image processing apparatus.   5. The image processing apparatus according to claim 3, wherein the accepting unit allows the user to select a job that uses a function provided by the image processing apparatus with respect to the conversion method.   5. The image processing apparatus according to claim 3, wherein the accepting unit causes the user to select in advance before accepting a job using a function provided by the image processing apparatus regarding the conversion method.   7. The display unit according to claim 2, wherein the reception unit displays a screen for selecting any of Red, Green, Blue, Cyan, Magenta, and Yellow as the specified color on the display unit. An image processing apparatus according to any one of the preceding claims. It further comprises generation means for generating a two-color conversion table for converting full-color print data into two-color print data according to the full-color conversion table and the designated color received by the reception means.
The said conversion means converts full-color print data into two-color print data using the said 2 color conversion table produced | generated by the said production | generation means in any one of the Claims 2 thru | or 7 characterized by the above-mentioned. Image processing device.   The image processing apparatus according to any one of claims 1 to 6, wherein the print data is input from an external device connected via a network. The image reading apparatus further comprises reading means for reading an image from a document and outputting image data.
The image processing apparatus according to any one of claims 1 to 6, wherein the print data is image data read from a document by the reading unit and output. A control method of the image processing apparatus,
An accepting step of accepting a user input specifying a conversion method for converting full color print data into two color print data when printing full color print data with two color materials;
And converting the full-color print data into two-color print data according to the conversion method received in the receiving step. It is a program for making a computer execute each process in a control method of an image processing device, and the control method is
An accepting step of accepting a user input specifying a conversion method for converting full color print data into two color print data when printing full color print data with two color materials;
A conversion step of converting the full-color print data into two-color print data according to the conversion method received in the reception step.

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