JP7321885B2 - Image processing device, image processing method, and program - Google Patents

Description

The present invention relates to a technique for adjusting image colors.

There is a technique for adjusting the color of an image using an image processing device. Color adjustment methods performed in image processing apparatuses include the following. First, a color to be adjusted (hereinafter referred to as an adjustment target color) is extracted from the image data of the image to be printed. In addition, a sample printed matter is read, and the user selects a target color (hereinafter referred to as sample color) of the color to be adjusted from the read image (hereinafter referred to as sample image). A target signal value required to reproduce the selected sample color is specified in consideration of the color reproduction characteristics of the image forming apparatus used for printing. Then, a color conversion table is adjusted (generated) so that a target signal value corresponding to the sample color is output when the color to be adjusted is input.

Japanese Patent Laid-Open No. 2002-103000 discloses that when extracting such an adjustment target color, the frequency of each color in an image is calculated, and color candidates for adjustment are displayed on a screen in descending order of frequency. Techniques for allowing a user to select a color are described.

JP 2011-205505 A

However, in the technique of Patent Document 1, when the image is a document centered on a document or an image with a white background, white or black is extracted as a color with high frequency, and white or black is displayed as a candidate for the color to be adjusted. end up Basically, white or black is not selected as a color to be adjusted, and there is a problem that unnecessary candidates are displayed on the screen.

An image processing apparatus according to an aspect of the present invention is an image processing apparatus that adjusts the color of an image, and includes reception means for receiving, from a user, designation of a position in the image displayed on a display means, and display on the display means. display control means for displaying color candidates according to the frequency of appearance of colors existing within a predetermined distance from the specified position in the image that has been displayed, wherein the display control means is configured to display the color candidate It is characterized by displaying candidates excluding achromatic colors among the candidates.

According to the present invention, suitable candidates can be displayed as the adjustment target color.

2 is a block diagram showing the hardware configuration of an image forming apparatus; FIG. FIG. 2 is a functional block diagram showing the internal configuration of the image processing apparatus; FIG. 3 is a functional block diagram showing the internal configuration of a color adjustment table generator; FIG. 4 is a diagram showing an example of a UI for displaying and operating image data and colors to be adjusted or sample colors; FIG. 4 is a diagram showing a flow of processing for extracting an adjustment target color or a sample color from image data; FIG. 4 is a diagram showing a flow of processing for extracting an adjustment target color or a sample color from image data; The figure which shows the flow of a sample color registration process. FIG. 10 is a diagram showing an example of displaying an extracted color as a sample color candidate;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described with reference to the drawings. It should be noted that the following embodiments do not limit the present invention, and not all combinations of features described in the embodiments are essential. In addition, the same configuration will be described by attaching the same reference numerals.

<<First Embodiment>>
The present embodiment relates to color adjustment processing for extracting an adjustment target color from an image and adjusting an output signal value corresponding to the signal value of the extracted adjustment target color to a target signal value. First, an example in which such color adjustment processing is required will be described.

In recent years, with the improvement in the performance of image forming apparatuses, apparatuses that achieve image quality equivalent to that of commercial printers have appeared. Therefore, printing of POPs and the like used in stores can be easily performed at each store. POP is an abbreviation for Point of purchase advertising, which is an advertisement for sales promotion. At this time, the POP may be printed in a color different from that of the sample POP due to a difference in the printing apparatus. In this embodiment, in such a case, adjustment is made so that the color is printed in the same color as the sample POP.

Here, when extracting the color to be adjusted (color to be adjusted) from the image data of the image to be printed, as a simple extraction method, the image is displayed, and the user touches a portion of the displayed image that has the color to be adjusted. and extract the color of the touched part. However, the screen size of the display panel mounted on the image forming apparatus is often small. As a result, the displayed image becomes small, and it may not be possible to touch the part where the color to be adjusted is present, and accurate color extraction may not be possible. Also, when automatically extracting frequently used colors as candidates for adjustment target colors, if the image to be printed is a document centered on a document or a POP with a white background, white or black is extracted as a candidate. put away. In view of the above points, in the present embodiment, an example of displaying suitable candidates for the adjustment target color when extracting the adjustment target color from the image data of the image to be printed will be described.

Note that the color adjustment process using a sample, which will be described in this embodiment, is widely applicable to image forming apparatuses that perform printing such as copiers, laser printers, or inkjet printers, or image display apparatuses such as monitors or projectors. It is possible. In this embodiment, an MFP (Multi Function Peripheral) having a scan function, a print function, a copy function, a transmission function, etc. will be described as an example. That is, an example in which the color adjustment processing of the present embodiment is performed in an image processing apparatus installed in an image forming apparatus will be described.

In the following embodiments, the colors corresponding to each color space held by the image data are represented by letters such as R, G, B or L, a, b. For example, R denotes the red component in the RGB color space. A relative color space based on the color reproduction range of a device such as a printer engine or scanner unit, which will be described later, is expressed as a "device-dependent color space" (or device-dependent color space). On the other hand, an absolute color space defined as a standard is expressed as a “device-independent color space” (or device-independent color space). Similarly to RGB, color materials to be recorded on the recording medium are represented by letters C (cyan), M (magenta), Y (yellow), and K (black) for each color.

Image data is two-dimensional data of a plurality of planes having a plane for each color. For example, image data in the RGB color space indicates layer structure data of three two-dimensional planes for each of R, G, and B. FIG. In this embodiment, color adjustment processing in the same color space is performed using table data holding values of discrete points in the color space. In addition, color conversion processing for converting values to express the same color in color spaces with different definitions, or color adjustment processing for converting color spaces after performing arbitrary adjustment processing is performed. Note that the discrete points in the color space described above are defined as grid points in this embodiment. A lattice point indicates one element such as RGB or Lab that constitutes table data representing a color space. A detailed example of table data will be described later.

<Hardware Configuration of Image Forming Apparatus>
FIG. 1 is a block diagram showing the hardware configuration of an image forming apparatus 100 according to this embodiment. Image forming apparatus 100 includes CPU 101 , ROM 102 , RAM 103 , mass storage device 104 , display unit 105 , operation unit 106 , engine interface (I/F) 107 , network I/F 108 , scanner I/F 109 and image processing device 114 . Prepare. These units are interconnected via a system bus 110 . The image forming apparatus 100 also includes a printer engine 111 and a scanner unit 112 . A printer engine 111 and a scanner unit 112 are connected to the system bus 110 via an engine I/F 107 and a scanner I/F 109, respectively. Note that the image processing device 114 may be configured as an independent device from the image forming device 100 .

CPU 101 controls the overall operation of image forming apparatus 100 . The CPU 101 reads programs stored in the ROM 102 to the RAM 103 and executes them, thereby executing various processes described later. A ROM 102 is a read-only memory, and stores a system activation program or a program for controlling the printer engine, character data or character code information, and the like. A RAM 103 is a volatile random access memory and is used as a work area for the CPU 101 and as a temporary storage area for various data. For example, the RAM 103 is used as a storage area for storing font data additionally registered by downloading or image files received from an external device. A large-capacity storage device 104 is, for example, an HDD or SSD, and various data are spooled, and used as a work area and for storing programs, information files, image data, and the like.

The display unit 105 is composed of, for example, a liquid crystal display (LCD), and is used to display the setting state of the image forming apparatus 100, the state of processing being executed, an error state, and the like. The display unit 105 is also used to display candidates for adjustment target colors or sample colors when performing color adjustment processing. The operation unit 106 is an operation reception unit that is configured by hard keys and an input device such as a touch panel provided on the display unit 105 and receives an input (instruction) by a user's operation. The operation unit 106 is used to change the settings of the image forming apparatus 100 or reset the settings. Further, the operation unit 106 is used to execute the color adjustment processing mode of the image forming apparatus 100 when executing the color adjustment processing.

The engine I/F 107 functions as an interface for controlling the printer engine 111 according to instructions from the CPU 101 when executing printing. Engine control commands and the like are transmitted and received between the CPU 101 and the printer engine 111 via the engine I/F 107 . Network I/F 108 functions as an interface for connecting image forming apparatus 100 to network 113 . Note that the network 113 may be, for example, a LAN or a telephone network (PSTN). Based on the print image data received from the system bus 110 side, the printer engine 111 forms a multi-color image on a recording medium such as paper by using developers (toners) of a plurality of colors (here, four colors of CMYK). do. The scanner I/F 109 functions as an interface for controlling the scanner unit 112 according to instructions from the CPU 101 when the scanner unit 112 reads an original. Scanner unit control commands and the like are transmitted and received between the CPU 101 and the scanner unit 112 via the scanner I/F 109 . Under the control of the CPU 101 , the scanner unit 112 reads an image of a document, generates read image data, and transmits the image data to the RAM 103 or the mass storage device 104 via the scanner I/F 109 .

<Configuration of image processing apparatus>
FIG. 2 is a functional block diagram showing the internal configuration of the image processing device 114. As shown in FIG. The image processing apparatus 114 includes an image input unit 201, a control command generation unit 202, a color adjustment table generation unit 203, a color conversion processing unit 204, a raster image processor (hereinafter RIP) unit 205, a halftone processing unit 206, and an image output unit. 207. These functional units are implemented by the CPU 101 reading out programs stored in the ROM 102 to the RAM 103 and executing them. Alternatively, some or all of these may be implemented in hardware such as ASICs or electronic circuits.

The image input unit 201 receives input of image data to be printed. The input image data is, for example, image data input from the host PC 115 via the network 113 and the network I/F 108 . Alternatively, image data stored in the mass storage device 104 may be input to the image input unit 201 . The input image data is, for example, 3-layer data that expresses each RGB signal corresponding to the sRGB color space, which is an RGB color space independent of the printer engine 111, in 8-bit 256-gradation. Note that sRGB in this embodiment refers to the standard of the RGB color space defined by IEC (International Electrotechnical Commission). Image data input to the image input unit 201 is sent to the control command generation unit 202 .

The control command generation unit 202 controls the color adjustment table generation unit 203 and the color conversion processing unit 204 and generates control commands for the RIP unit 205 based on the input image data (sRGB). A RIP unit control command generated by controlling the color adjustment table generation unit 203 and the color conversion processing unit 204 is sent to the RIP unit 205 . The RIP unit command includes image data converted from the sRGB color space to the CMYK color space used by the printer engine 111 .

A color adjustment table generation unit 203 performs arbitrary color adjustment based on instructions from the operation unit 106 . The color adjustment table generation unit 203 performs color adjustment conversion of the image data input to the image input unit 201 from the sRGB color space independent of the printer engine 111 to the RGB color space dependent on the color reproducibility of the printer engine 111. Generate a color adjustment table for A device-dependent RGB color space that depends on the color reproducibility of the printer engine 111 is hereinafter referred to as a devRGB color space.

In the present embodiment, as described above, for example, as a result of printing by the printer engine 111 using POP image data, it is assumed that the POP is printed in a color different from that of the sample POP. Then, the user who recognizes that the color of the printed result is different from that of the sample operates the operation unit 106 to input an instruction to perform color adjustment (instruction of color adjustment mode). In response to this instruction, the color adjustment table generation unit 203 performs the color adjustment table generation processing described below. That is, the example described below is processing when an instruction for the color adjustment mode is input. When such a color adjustment mode instruction is not input, the image processing device 114 does not perform processing using the color adjustment table generation unit 203, and uses a default color adjustment table to convert the sRGB color space to the devRGB color space. conversion will be performed. The processing performed when the instruction for the color adjustment mode is not input is not the focus of the present embodiment, and thus the description thereof will be omitted.

The color adjustment table generation unit 203 of the present embodiment generates color adjustment table data in which colors corresponding to adjustment target colors included in the color adjustment table are color-adjusted so as to change to sample colors. This realizes color adjustment that brings the color closer to the color intended by the user. As described above, this color adjustment table data is table data for color adjustment conversion from the sRGB color space to the devRGB color space.

The color adjustment table generation unit 203 has default table data for color adjustment conversion from the sRGB color space to the devRGB color space. Here, when color adjustment is performed to bring the color to be adjusted closer to the sample color, the second color that is output when the color to be adjusted is input as the first color into the predetermined table is adjusted. That is, a color adjustment table adjusted to replace the second color with the third color that would be output if the sample colors were input to the predetermined table is generated. In other words, in the generated color adjustment table, when the color to be adjusted is input as the first color, the third color is output. The color adjustment table generation unit 203 according to the present embodiment performs processing for displaying suitable adjustment target color candidates when generating color adjustment table data. The details of the process of generating the color adjustment table will be described later.

The color conversion processing unit 204 uses the color adjustment table and the color conversion table generated by the color adjustment table generation unit 203 to convert the RGB values (sRGB values) of the image data acquired from the control command generation unit 202 into CMYK colors. Perform color conversion processing to convert to a color in space. A color conversion table is stored in the RAM 103 or the mass storage device 104 . First, the color conversion processing unit 204 converts the input image (sRGB) into the devRGB color space using the color adjustment table generated by the color adjustment table generation unit 203, thereby bringing the color to be adjusted closer to the sample color. Of course, colors other than the color to be adjusted are also converted from the sRGB color space to the devRGB color space. By performing color adjustment in this manner, the input image is color-adjusted from the printer engine 111-independent RGB color space to the devRGB color space, and the color to be adjusted is brought closer to the sample color. Furthermore, the color conversion processing unit 204 performs color conversion processing using two color conversion tables: a color conversion table for converting from the devRGB color space to the Lab color space, and a color conversion table for color conversion from the Lab color space to the CMYK color space. Apply. As a result, the input image is converted into color values in the CMYK color space. In the present embodiment, L*a*b*, which is a three-dimensional visually uniform color space independent of the printer engine 111 that takes into account human visual characteristics and is defined by the CIE (International Commission on Illumination), is simply Labeled as Lab. By converting the color space via a color space independent of the printer engine 111, reproduction of colors that humans recognize as the same color is realized. Note that the method of color conversion processing from the devRGB color space to the CMYK color space is not limited to using the two color conversion tables described above. For example, a color adjustment table and two color conversion tables may be synthesized to generate a single color conversion table for converting the devRGB color space to the CMYK color space, and color conversion may be performed using this color conversion table. good.

The RIP unit 205 generates a CMYK raster image using the RIP unit control commands (including image data in the CMYK color space) generated by the control command generation unit 202 .

A halftone processing unit 206 performs halftone processing on the CMYK raster image generated by the RIP unit 205 . The printer engine 111 usually supports output of only the number of gradations lower than input image data expressing 256 gradations, such as 2, 4, and 16 gradations. For this reason, the halftone processing unit 206 performs halftone processing so as to enable stable halftone expression output even with a small number of gradations. For the halftone processing by the halftone processing unit 206, various methods such as the density pattern method, systematic dither method, error diffusion method, etc. can be applied. Print image data, which is image data that can be processed by the printer engine 111, is generated through these processes.

Upon receiving print image data from the halftone processing unit 206 , the image output unit 207 transmits the print image data to the printer engine 111 via the engine I/F 107 . The CPU 101 instructs the printer engine 111 to form an image based on the print image data. The printer engine 111 prints a color image according to the input print image data on a recording medium by executing each process of exposure, development, transfer, and fixation.

<Configuration of Color Adjustment Table Generation Unit>
FIG. 3 is a functional block diagram showing the internal configuration of the color adjustment table generator 203. As shown in FIG. The color adjustment table generation unit 203 includes an adjustment target color acquisition unit 301 , a sample color acquisition unit 302 , a range acquisition unit 303 , a determination unit 304 , a determination unit 305 and a color conversion table output unit 306 . These functional units are implemented by the CPU 101 reading out programs stored in the ROM 102 to the RAM 103 and executing them. Alternatively, some or all of these may be implemented in hardware such as ASICs or electronic circuits.

The adjustment target color acquisition unit 301 receives input of image data (sRGB) from the control command generation unit 202 . After obtaining the image data, the adjustment target color obtaining unit 301 displays an image based on the image data on the display unit 105 via the system bus 110 .

FIG. 4 is a diagram showing an example of a UI for displaying an image corresponding to image data and a color to be adjusted or a sample color displayed on the display unit 105 and enabling operation. The UI in FIG. 4 is displayed by controlling the display of the display unit 105 by the color adjustment table generation unit 203 (more specifically, the adjustment target color acquisition unit 301 or the sample color acquisition unit 302). An image 402 displayed on the display unit 105 in FIG. 4A is an image (first image) displayed based on the image data acquired by the adjustment target color acquisition unit 301 . An image 402 is an image corresponding to the sample 401 (printed matter), but is displayed with some colors different.

When the user selects a specific position of the image 402 displayed on the display unit 105 (for example, the user touches the screen), the adjustment target color acquisition unit 301 acquires a color corresponding to the position selected by the user. is determined as a candidate for the color to be adjusted. As will be described later, the "color corresponding to the position selected by the user" includes the color of the position specified by the user and the color existing within a predetermined distance from the specified position. Therefore, the color corresponding to the position selected by the user can include a plurality of colors, and these are determined as candidates for the adjustment target color.

Then, the adjustment target color acquisition unit 301 displays the determined adjustment target color candidate colors on the display unit 105 so as to display the color of the image portion, such as the candidate 404 in FIG. 4A. Also, check boxes 403 are provided near the candidates 404 to allow the user to select a color to be adjusted from among the candidates 404 . A scroll bar 405 is a scroll bar for scrolling the screen to change the displayed adjustment target color candidates when a plurality of adjustment target color candidates are extracted and do not fit on one screen. Three values of R, G, and B corresponding to sRGB are also displayed in the vicinity of the extracted adjustment target color candidate 404 .

The adjustment target color acquisition unit 301 acquires the color checked in the check box 403 as the adjustment target color. The adjustment target color acquired by the adjustment target color acquisition unit 301 is sent to the determination unit 305 . The details of the adjustment target color acquisition process will be described later.

The image 402 and the adjustment target color candidates 404 displayed on the display unit 105 are displayed in an RGB color space dependent on the monitor device using a monitor color conversion table dependent on the monitor device of the display unit 105. There is.

The sample color acquisition unit 302 acquires a target color (sample color) of the color to be adjusted. The flow of acquiring sample colors will be described with reference to FIGS. 4(a) and 4(b). The sample color acquisition unit 302 displays a message 408 indicating an instruction to read the sample 401 on the display unit 105, as shown in FIG. 4B. After confirming this reading instruction, the user sets the sample 401 on the scanner unit 112 and instructs execution of reading via the operation unit 106 . In response to this instruction, the image processing device 114 reads the document (sample 401 ) containing the sample color set in the scanner unit 112 via the system bus 110 to generate image data and records it in the RAM 103 . The image data recorded in the RAM 103 is, for example, RGB 8-bit image data. The read image data is also converted from the device-dependent RGB values of the scanner unit 112 to the sRGB color space using the scanner color conversion table. The sample color acquisition unit 302 displays the image data thus obtained on the display unit 105 in the same manner as the processing described for the adjustment target color acquisition unit 301 (FIG. 4A).

Similar to the adjustment target color acquisition unit 301, the sample color acquisition unit 302 is selected by the user from the displayed sample image (second image, corresponding to the image 402), for example, by the user touching the screen. Display the color corresponding to the position as the sample color. At this time, the sample color acquisition unit 302 displays sample color candidates (corresponding to the candidate 404) in the same manner as the adjustment target color, and acquires the color checked in the check box 403 as the sample color (see FIG. 4 ( a)). The acquired sample color is sent to the determination unit 304 . The details of the sample color acquisition process will be described later.

Range acquisition unit 303 acquires the color reproduction range of image forming apparatus 100 from control command generation unit 202 . The color reproduction range indicates the range of colors that can be expressed by the image forming apparatus 100 in Lab space, for example. The color reproduction range is acquired as table data representing the relationship of Lab corresponding to RGB (devRGB) depending on the printer engine 111 . Table 1 shows an example of table data.

However, the color space used as the color reproduction range is not limited to the above example as long as it does not depend on the printer engine 111 . For example, like the Lab color space, the Luv color space defined by the CIE (Commission Internationale de l'Eclairage) may be used. Lab values are real numbers in this embodiment, L is 0.0 to 100.0, and a and b are -127.0 to 128.0. The table data holds discrete position values in the RGB color space corresponding to devRGB. When a point that does not hold a value is specified, the range acquisition unit 303 calculates the Lab value by interpolation calculation from surrounding values. The acquired color reproduction range is sent to the determination unit 304 .

Based on the sample color sent from the sample color acquisition unit 302 and the color reproduction range sent from the range acquisition unit 303, the determination unit 304 determines that the Lab value corresponding to the sample color is the color reproduction in the image forming apparatus 100. Determine whether or not the range is exceeded. A determination result is sent to the determination unit 305 .

The determination unit 305 determines a target signal value corresponding to the adjustment target color acquired by the adjustment target color acquisition unit 301 according to the determination result sent from the determination unit 304 . Three values of R, G, and B of devRGB are used as target signal values. That is, the determining unit 305 determines the target signal value in the devRGB color space of the output when the input is the adjustment target color in the sRGB color space in the adjustment table for color adjustment from the sRGB color space to the devRGB color space.

When the determination result of the determination unit 304 does not exceed the color reproduction range, the determination unit 305 determines the devRGB values that allow the image forming apparatus 100 to reproduce the Lab values corresponding to the sample color as target signal values. On the other hand, if the determination result exceeds the color reproduction range, a color close to the color desired by the user may be selected within the color reproduction range. For example, the determination unit 305 generates a chart image with multiple candidate colors, and the user selects a color close to the desired color from the chart image. Then, the determination unit 305 may determine the color of the chart image selected by the user as the target signal value. The chart image may be printed by the printer engine 111 or displayed on the display unit 105 . The target signal value thus determined is sent to the color conversion table output unit 306 together with the color to be adjusted.

The color conversion table output unit 306 generates table data that associates the received adjustment target color with the target signal value, and sends the table data to the color conversion processing unit 204 . The color adjustment table is a table that converts input sRGB into an RGB (devRGB) color space that depends on the printer engine 111 . Colors other than the color to be adjusted may be generated using the values of the predetermined color adjustment table. Table 2 shows an example of the color adjustment table.

The devRGB values of the lattice points corresponding to the sRGB values indicated by the adjustment target color are replaced with the target signal values. Through the replacement process described above, a table is generated that realizes an adjustment that brings the color to be adjusted closer to the color desired by the user. More preferably, instead of changing only one grid point, smoothing processing is performed so that the difference in output signal value between the grid point indicated by the adjustment color and adjacent grid points on the RGB color space changes smoothly. It is desirable to

<Acquisition processing flow of color to be adjusted and sample color>
FIG. 5 is a diagram showing a flow of processing for extracting a color to be adjusted or a sample color from image data. The processing in FIG. 5 is performed by the adjustment target color acquisition unit 301 or the sample color acquisition unit 302 . A series of processes shown in the processing flow of FIG. 5 is realized by the CPU 101 reading a program stored in the ROM 102 to the RAM 103 and executing the program. Note that the symbol "S" in the description of each process means a step in the flowchart. Colors extracted in the adjustment target color and sample color extraction processing are collectively referred to as extraction colors. The processing mainly performed by the adjustment target color acquisition unit 301 will be described below. Since the extraction of the color to be adjusted and the sample color are performed in the same processing flow, the sample color acquisition unit 302 replaces the color to be adjusted acquisition unit 301 and the sample color to be adjusted, unless otherwise described.

In S501, the adjustment target color acquisition unit 301 receives image data. The adjustment target color acquisition unit 301 receives image data sent from the control command generation unit 202 . When extracting a sample color as an extraction color, the sample color acquiring unit 302 receives image data read by the scanner unit 112 and recorded in the RAM 103 .

In S<b>502 , the adjustment target color acquisition unit 301 displays the image data received in S<b>501 on the display unit 105 via the system bus 110 . As described above, the image data is displayed on the display unit 105 in the form of the image 402 in FIG. 4A, for example.

In S503, the adjustment target color acquisition unit 301 receives the position selection of the adjustment target color (extracted color) from the user for the image 402 displayed on the display unit 105 in S502. The selection of the position of the color to be adjusted is performed by having the user touch a portion of the image 402 displayed on the display unit 105 where the color to be adjusted is arranged via a touch panel or the like. Alternatively, the user may select using a pointing device such as a mouse connected as the operation unit 106 . Then, the adjustment target color acquisition unit 301 holds the coordinates (x, y) of the position touched by the user. Here, x and y are the horizontal position x (the right direction is + ) and the vertical position y (the downward direction is +).

Subsequently, in S504, the adjustment target color acquisition unit 301 extracts the signal values (sRGB) of the pixel at the position selected in S503 and its peripheral pixels, and derives the frequency of appearance thereof. Peripheral pixels are pixels within a predetermined range of left, right, top and bottom distances on a two-dimensional plane from the pixel at the selected position. For example, if the selected position is (Cx, Cy), the left distance is Dxl, the right distance is Dxr, the upper distance is Dyu, and the lower distance is Dyd, then the range of surrounding pixels is It can be expressed as follows.
Cx - Dxl ≤ Cx ≤ Cx + Dxr
Cy−Dyu≦Cy≦Cy+Dyd
however,
If Cx - Dxl < 0 then Cx - Dxl = 0
If Cx + Dxr > MAXx then Cx + Dxr = MAXx
If Cy-Dyu < 0 then Cy-Dyu = 0
If Cy + Dyd > MAXy then Cy + Dyd = MAXy

Here, MAXx is the maximum position of the display image in the horizontal direction, and MAXy is the maximum position of the display image in the vertical direction.

Although an example in which the range of peripheral pixels is a predetermined distance has been described, the range may be changed according to the image size of the image data, or the range may be determined by the user.

The appearance frequency is derived by counting the number of pixels having the same signal value among the signal values of the pixel at the selected position and its surrounding pixels. For example, let the position of the selected pixel and its surrounding pixels on a two-dimensional plane be i in the horizontal direction, j in the vertical direction, and let the position of the upper leftmost pixel be the origin (0, 0). Each pixel value is expressed as Vij (Rij, Gij, Bij). First, an ID is assigned (ID: 001) while holding the signal values (R00, G00, B00) of V00, and Ct001=1 representing the number of signal values of ID: 001 is set. Subsequently, the signal values of V10 and V00 are compared, and if the signal values are the same, 1 is added to the value of Ct001 representing the number of ID:001. Otherwise, an ID is assigned (ID: 002) while the signal values (R10, G10, B10) of V10 are held, and Ct002 representing the number of signal values of ID: 002 is set to 1. The signal value of each pixel of the pixel of the selected position and its peripheral pixels is similarly compared with each signal value to which the ID is assigned, and if there is no identical signal value, the signal value is held and an ID is assigned, If they are the same, add 1 to the corresponding Ct value. The adjustment target color acquisition unit 301 counts the number of pixels having the same signal value among the signal values of the pixel at the position selected in this way and the surrounding pixels, and obtains a pixel value, an ID, and a count value. (Ct) is held in the RAM 103 .

Next, in S505, the adjustment target color acquisition unit 301 determines whether the signal values extracted in S504 are color signal values. Whether or not the image is color can be determined based on whether the extracted signal values are R=G=B, that is, whether R, G, and B are all the same value. If R=G=B, it is determined to be color. In this embodiment, as the simplest determination method, an example of determining whether or not the extracted signal value is R=G=B has been described. However, it is also possible to calculate the difference between the values of R, G, and B, and determine that the image is in color if the difference is greater than a predetermined range. Further, while converting the RGB values into Lab values, the saturation may be calculated from the Lab values, and if the saturation is greater than a predetermined value, it may be determined as color. That is, the RGB values can be converted into saturation, and if the saturation is greater than a predetermined value, it can be determined as color.

If it is determined that the extracted signal value is not color, the process advances to S506 to discard the extracted signal value held in S504 from the RAM 103 .

After the process of S506 or when the extracted signal value is determined to be color in S505, the process proceeds to S507. In S<b>507 , the adjustment target color acquisition unit 301 determines whether all the signal values of the pixel at the selected position and its peripheral pixels extracted in S<b>504 have undergone color determination. As a determination method, for example, the number of pixels extracted in S504 is held as a value, and the held value is decremented by 1 each time S505 to S507 are processed. Judge. If it is determined in S507 that all the images have not been color-determined, the process returns to S505.

If it is determined in S507 that all the extracted signals have undergone color determination, in S508 the adjustment target color acquisition unit 301 sorts the signal values (extracted colors) held in the RAM 103 through S505 to S507 in descending order of appearance frequency. They are arranged and displayed on the display unit 105 . For example, like the candidate 404 in FIG. 4(a), the color of the signal value with the highest frequency is displayed at the top in a patch format, followed by each signal value in a patch format in descending order of frequency. Display colors. This is because the color with the higher frequency is more likely to be the color to be adjusted (extracted color) selected by the user. If the number of signal values to be displayed is large and cannot be displayed on the screen at one time, the scroll bar 405 is operated to display signal values of low frequency order.

Subsequently, in step S<b>509 , the adjustment target color acquisition unit 301 receives selection of a color by the user from among the signal value color candidates 404 displayed on the display unit 105 . For example, by checking the check box 403 in FIG. 4A, selection of color is accepted. In addition to the check box 503, the color may be selected by the user touching the candidate 404. FIG.

Finally, in step S510, the adjustment target color acquisition unit 301 detects that the user has selected a color and pressed the enter button 506, thereby registering the selected color as an adjustment target color. When the extracted color is a sample color, the sample color acquisition unit 302 registers the selected selected color as the sample color.

In the present embodiment, signal value extraction is performed centering on the position of the color to be adjusted selected by the user in S503, but the selection of the position of the color to be adjusted by the user may be omitted. That is, by performing the processing after S504 on the entire received image data, the user can omit the position selection of the color to be adjusted. Although this may increase the processing load, it is possible to reduce the user's operation and reduce the user's load. In addition, although all color signal values are displayed as selection candidates, signal values with a predetermined frequency or less may be excluded from the frequencies calculated in S504.

Further, the registration of the sample color is performed in the same process as the registration of the color to be adjusted, but based on the color to be adjusted registered in S510, candidates for the sample color may be narrowed down and selected. For example, sample colors can be registered as shown in the processing flow of FIG.

FIG. 7 is a diagram showing the flow of sample color registration processing. The processing in FIG. 7 is performed by the sample color acquisition unit 302 . A series of processes shown in the processing flow of FIG. 7 is realized by the CPU 101 reading a program stored in the ROM 102 to the RAM 103 and executing the program. Note that the symbol "S" in the description of each process means a step in the flowchart.

First, in S701, the sample color acquisition unit 302 acquires image data read by the scanner unit 112 and recorded in the RAM 103 as read image data.

Next, in S702, the sample color acquisition unit 302 acquires the signal value (sRGB) of the adjustment target color (hereinafter referred to as the selected adjustment target color) selected and registered by the user in the processing of S501 to S510 in FIG. .

Next, in S703, the sample color acquisition unit 302 extracts signal values close to the signal value of the selected adjustment target color acquired in S702 from among the signal values of the read image data received in S701. Specifically, the distance in the sRGB space between the sRGB value of the color to be selected and adjusted and the signal value (sRGB value) of each pixel of the read image data is calculated, and the calculated distance value is a predetermined threshold value. Extract those that are within The calculation of the distance on the sRGB space is performed using the following Equation 1.
Dist = sqrt((Rs-Rt)^2 + (Gs-Gt)^2 + (Bs-Bt)^2) Formula 1

Here, Dist represents distance. Rs, Gs, and Bs are the sRGB values of the selected adjustment target color, Rt, Gt, and Bt are the sRGB values of the pixel to be processed in the read image data, sqrt is the square root calculation, and ^ is the exponentiation calculation.

The value of Dist is compared with a predetermined threshold, and it is determined for each pixel of the read image data whether the value of Dist is equal to or less than the threshold, that is, whether the signal values of the selected adjustment target color and the read image data are close to each other. . Also, the distance in the Lab space may be used instead of the sRGB space. In that case, for example, the sRGB values are converted to Lab values using the above-described color adjustment table and table representing the color reproduction range, and R, G, and B in Equation 1 are replaced with L, a, and b, respectively, to calculate good. As for the threshold value, a value set in advance may be referred to. The threshold may be set according to the characteristics of Also, the number of colors of the read image data that are determined to be colors close to the color to be adjusted is stored for determination in S704, which will be described later. Specifically, 0 is held in the initial state, and 1 is added each time it is determined to be a similar color, and the count is incremented. Holds the value after counting up the result.

In S704, the sample color acquisition unit 302 determines whether or not there is a color of the read image data that was determined in S703 to be close to the color to be adjusted. If the number of colors determined to be close colors stored in S703 is 1 or more, it is determined that the color exists, and if the number is 0, it is determined that the color does not exist. If it is determined that it does not exist, the process ends.

If it is determined in S704 that the sample color acquisition unit 302 exists, in S705 the sample color acquisition unit 302 displays the signal value (extracted color) held in the RAM 103 on the display unit 105 in S703. FIG. 8 is an example of a case where extracted colors are displayed on the display unit 105. FIG. FIG. 8 shows an example of displaying an extracted color as a sample color candidate on the display unit 105 . The screen in FIG. 8 displays the selected adjustment target color 801 acquired in S702, the color candidate 803 extracted in S703, the sample color 802 selected by the user from among the color candidates 803, and the selection of the sample color. Includes a decision button 805 to exit. The display of the color candidates 803 can be arranged from the top in descending order of the color closest to the color to be adjusted, that is, the smaller value of Dist calculated in S703. Alternatively, they may be arranged in order of appearance frequency as in S508 described above. By operating the scroll bar 804, signal values that cannot be displayed on the screen at one time can be displayed with a large Dist value or with a low frequency order.

In S706, the sample color acquisition unit 302 receives designation of the sample color selected by the user from among the color candidates 803 displayed in S705.

Finally, in S707, the sample color acquisition unit 302 registers the selected sample color by detecting that the OK button 805 has been pressed while the user has selected the sample color selected in S706. Then, as described above, a color adjustment table is generated based on the registered color to be adjusted and the sample color.

By doing so, it is possible to select colors more easily when selecting sample colors, especially when the screen is small. Although an example in which a user selects a sample color from a plurality of candidates when a plurality of sample color candidates are extracted has been described, the user may select a sample color when the sample color candidate is a single color. Instead, a swatch color may be determined.

As described above, according to the present embodiment, it is possible to prevent an achromatic color such as white or black, which is not selected as an adjustment target, from being displayed on the screen as a candidate. Therefore, suitable candidates can be displayed as the adjustment target color. Moreover, even on a small screen, it is possible to prevent an undesired color from being extracted as an adjustment target color due to a touch error or the like. In addition, when an adjustment target color is registered, sample color candidates close to the adjustment target color can be displayed. This also makes it possible to easily select a sample color.

<<Second Embodiment>>
In the first embodiment, an example has been described in which the adjustment target color is registered by the user's selection from among the extracted adjustment target color candidates. However, depending on the structure of the input image, the color to be adjusted may be registered without being selected by the user. For example, there is a case where there is only one color in the image, or a case where an image for adjustment, such as a patch image, in which only colors to be adjusted are arranged is input. Therefore, in the present embodiment, an example will be described in which if the number of candidates for the extracted adjustment target color is equal to or less than a predetermined value, the adjustment target color is registered without receiving color selection from the user.

As in the first embodiment, the registration of the sample color can also be realized by the same process as the registration of the adjustment target color. Also, the configuration of the image processing apparatus 114 of this embodiment is the same as that of the example described in the first embodiment, so description thereof will be omitted here.

FIG. 6 is a diagram showing the flow of processing for extracting a color to be adjusted or a sample color from image data. The processing in FIG. 6 is performed by the adjustment target color acquisition unit 301 or the sample color acquisition unit 302 . Since the extraction of the color to be adjusted and the extraction of the sample color are the same processing flow, they will be described together. Processing performed by the adjustment target color acquisition unit 301 will be described below.

Since steps S601 to S607 in FIG. 6 are the same as steps S501 to S507 in FIG. 5, description thereof will be omitted.

In S<b>608 , the adjustment target color acquisition unit 301 determines whether the number of signal values held in the RAM 103 through the processing up to S<b>607 is equal to or less than a predetermined number. The predetermined number may be a value held in advance or may be a value based on input from the user. For example, the predetermined number can be "1". For the determination in S608, the number of signal values finally held in S607 is held in the RAM 103, and the number of signal values held in the RAM 103 is read out in S608 and compared with a predetermined number. Alternatively, if the maximum value of the ID given in S604 is made equal to the number of signal values that are finally held, the maximum value of the ID may be compared with a predetermined number.

If it is determined in S608 that the number of held signal values is equal to or less than the predetermined number, in S611 the adjustment target color acquisition unit 301 registers the held signal values as the adjustment target color or the sample color. Since the processing of S611 is the same as the processing of S510, description thereof is omitted.

On the other hand, if it is determined in S608 that the number of signal values held is greater than the predetermined number, the adjustment target color acquiring unit 301 performs the processes of S609 and S610. Since the processing of S609 and S610 is the same as the processing of S508 and S509, the description thereof is omitted.

Although the case where the predetermined number is "1" has been described as an example, the predetermined number may be "2" or more. For example, a plurality of colors may be registered as adjustment target colors without going through the processes of S609 and S610. In this case, registration of sample colors for each color may be performed again in the process of FIG.

As described above, according to the present embodiment, in the case of an image configuration in which the color to be adjusted and the sample color are clear, it is possible to register the color to be adjusted and the sample color with a reduced number of user operations.

<<other embodiments>>
In the above-described embodiment, the scanner unit 112 scans the sample image and registers the sample color, but the scanner unit 112 may not scan the sample color. For example, the display unit 105 displays color candidates similar to the adjustment target color, such as colors whose RGB values are within a predetermined range or colors whose Lab values are within a predetermined range, from the color of the adjustment target color. good too. Alternatively, the printer engine 111 may print a chart image of these approximate color candidates to allow the user to select a sample color.

Further, in the above-described embodiment, an example in which the image of the sample 401 equivalent to the image to be printed has been read by the scanner unit has been described. good.

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 a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

Claims (20)

An image processing device that adjusts the color of an image,
receiving means for receiving, from a user, designation of a position in the image displayed on the display means;
display control means for displaying color candidates according to the appearance frequency of colors present within a predetermined distance from the specified position in the image displayed on the display means;
has
The image processing apparatus, wherein the display control means displays candidates of the colors excluding achromatic colors. 2. The image processing apparatus according to claim 1, wherein the appearance frequency indicates the number of pixels having the same pixel value among pixels existing within the predetermined distance from the designated position. The pixel value has a signal value of each color of RGB,
3. The image processing apparatus according to claim 2, wherein said display control means determines that a pixel value having the same signal value for each of said RGB colors is said to be said achromatic color. The pixel value has a signal value of each color of RGB,
3. The method according to claim 2, wherein the display control means calculates a difference between the signal values of the RGB colors, and determines a pixel value in which the difference is smaller than a predetermined range as the achromatic color. image processing device. the pixel value is convertible to a value corresponding to saturation;
3. The image processing apparatus according to claim 2, wherein the display control means determines that the pixel value with the saturation equal to or less than a predetermined value is the achromatic color. The receiving means is configured to be capable of receiving designation of a specific candidate when there are a plurality of color candidates displayed on the display means,
6. The apparatus according to any one of claims 1 to 5, further comprising determining means for, when receiving designation of said specific candidate, determining said designated candidate as a color to be adjusted, which is a color to be adjusted. 1. The image processing device according to claim 1. 7. The method according to claim 6, wherein when the number of color candidates is equal to or less than a predetermined number, the determining means determines the color candidate as the adjustment target color without receiving the color candidate from the receiving means. image processing device. acquisition means for acquiring a sample color corresponding to the adjustment target color;
generating means for generating an adjustment table for adjusting the color to be adjusted to a color corresponding to the sample color;
8. The image processing apparatus according to claim 6, further comprising: The adjustment table is configured to output a second pixel value in a device-dependent color space when a first pixel value in a device-independent color space is input. 9. The image processing apparatus according to claim 8. The generating means is
having a predefined table for converting from the device-independent color space to the device-dependent color space;
When the pixel value of the adjustment target color is set as the first pixel value in the adjustment table,
10. The adjustment table is generated such that a pixel value output when the sample color is input to the predetermined table is set as the second pixel value in the adjustment table. The image processing device according to . The display control means displays a second image including the sample color on the display means,
The reception means receives a position designation from the user in the second image displayed on the display means,
The display control means is
configured to display the sample color candidates according to the frequency of appearance of colors existing within a predetermined distance from the specified position in the second image;
11. The image processing apparatus according to any one of claims 8 to 10, wherein, of the sample color candidates, candidates excluding achromatic colors are displayed. The display control means displays on the display means, among the second image including the sample color, the color whose signal value is within a predetermined threshold value from the color to be adjusted as a candidate for the sample color. 11. The image processing apparatus according to any one of claims 8 to 10, wherein the image processing apparatus is configured as follows. The receiving means is configured to be able to receive designation of a specific candidate when there are a plurality of candidates for the displayed sample color for the second image,
13. The image processing apparatus according to claim 11, wherein when the specification of the specific candidate is accepted, the obtaining means obtains the specific candidate as the sample color. When the number of displayed sample colors for the second image is equal to or less than a predetermined number, the obtaining means does not receive the reception by the receiving means, and uses the displayed sample color candidate as the sample color. 13. The image processing apparatus according to claim 11 or 12, wherein the image processing apparatus acquires. An image processing device that adjusts a color included in a first image to a sample color,
acquisition means for acquiring image data of the first image and image data of a second image including the sample color;
receiving means for receiving, from a user, designation of a position in the first image displayed on the display means and designation of a position in the second image displayed on the display means;
When the designation of the position in the first image displayed on the display means is accepted, the color to be adjusted is determined according to the appearance frequency of the color existing within a predetermined distance from the designated position in the first image. displaying on the display means the candidate for the color to be adjusted,
When the designation of the position in the second image displayed on the display means is accepted, the sample color is changed according to the appearance frequency of the color existing within a predetermined distance from the designated position in the second image. display control means configured to display candidates on the display means;
determining the color to be adjusted from among the candidates for the color to be adjusted displayed on the display means according to an instruction from a user;
determination means for determining the sample color from the sample color candidates displayed on the display means according to a user's instruction when the sample color candidates are displayed on the display means;
generating means for generating an adjustment table for adjusting the determined adjustment target color to a color corresponding to the determined sample color;
has
The image processing apparatus, wherein the display control means displays candidates excluding achromatic colors from among the candidates. An image processing device that adjusts a color included in a first image to a sample color,
acquisition means for acquiring image data of the first image and image data of a second image including the sample color;
receiving means for receiving, from a user, designation of a position in the first image displayed on the display means;
When the designation of the position in the first image displayed on the display means is accepted, the color to be adjusted is determined according to the appearance frequency of the color existing within a predetermined distance from the designated position in the first image. a first control means for displaying, on the display means, candidates for adjustment target colors excluding achromatic colors;
a first determination means for determining the adjustment target color from the adjustment target color candidates displayed on the display means according to a user's instruction when the adjustment target color candidates are displayed on the display means; ,
(2) displaying on the display means, among the second image including the sample colors, colors having signal values whose distance from the determined color to be adjusted is within a predetermined threshold value as candidates for the sample colors; a control means;
a second determination means for determining the sample color from the sample color candidates displayed on the display means according to a user's instruction when the sample color candidates are displayed on the display means;
generating means for generating an adjustment table for adjusting the determined adjustment target color to a color corresponding to the determined sample color;
An image processing device comprising: An image processing method for adjusting the color of an image, comprising:
a receiving step of receiving from a user a designation of a position in the image displayed on the display means;
a display step of displaying color candidates according to the appearance frequency of colors present within a predetermined distance from the specified position in the image displayed on the display means;
has
The image processing method, wherein, in the display step, candidates of the colors excluding achromatic colors are displayed. An image processing method for adjusting a color contained in a first image to a sample color,
an obtaining step of obtaining image data for the first image and image data for a second image including the sample colors;
a receiving step of receiving, from a user, designation of a position in the first image displayed on the display means and designation of a position in the second image displayed on the display means;
When the designation of the position in the first image displayed on the display means is accepted, the color to be adjusted is determined according to the appearance frequency of the color existing within a predetermined distance from the designated position in the first image. displaying on the display means the candidate for the color to be adjusted,
When the designation of the position in the second image displayed on the display means is accepted, the sample color is changed according to the appearance frequency of the color existing within a predetermined distance from the designated position in the second image. a display control step configured to display candidates on the display means;
determining the color to be adjusted from among the candidates for the color to be adjusted displayed on the display means according to an instruction from a user;
a determination step of determining the sample color from the sample color candidates displayed on the display means according to a user's instruction when the sample color candidates are displayed on the display means;
a generation step of generating an adjustment table for adjusting the determined adjustment target color to a color corresponding to the determined sample color;
has
The image processing method, wherein in the display control step, among the candidates, candidates excluding achromatic colors are displayed. An image processing method for adjusting a color contained in a first image to a sample color,
an obtaining step of obtaining image data for the first image and image data for a second image including the sample colors;
a receiving step of receiving, from a user, designation of a position in the first image displayed on the display means;
When the designation of the position in the first image displayed on the display means is accepted, the color to be adjusted is determined according to the appearance frequency of the color existing within a predetermined distance from the designated position in the first image. a first control step of displaying, on the display means, candidates for adjustment target colors excluding achromatic colors;
a first determination step of determining the color to be adjusted from among the candidates for the color to be adjusted displayed on the display means according to an instruction from a user when the candidates for the color to be adjusted are displayed on the display means; ,
(2) displaying on the display means, among the second image including the sample colors, colors having signal values whose distance from the determined color to be adjusted is within a predetermined threshold value as candidates for the sample colors; a control step;
a second determination step of determining the sample color from the sample color candidates displayed on the display means according to a user's instruction when the sample color candidates are displayed on the display means;
a generation step of generating an adjustment table for adjusting the determined adjustment target color to a color corresponding to the determined sample color;
An image processing method characterized by comprising: A program for causing a computer to function as each unit included in the image processing apparatus according to any one of claims 1 to 16.

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