JP5691526B2 - Image processing apparatus, image processing program, and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus, an image processing program, and an image processing method, and more particularly to image processing for adjusting the color of an image to be output according to a color gamut that can be reproduced by an apparatus that outputs an image.

  In recent years, there has been a tendency to digitize information, and image processing apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Such an image processing apparatus is often configured as a multifunction machine that can be used as a printer, a facsimile, a scanner, or a copier by providing an imaging function, an image forming function, a communication function, and the like.

  On the other hand, in image generation devices such as PCs (Personal Computers), scanners, and cameras, and input devices, and image output devices such as color printers and wide color gamut displays, the reproducible color gamut differs depending on the type and model of the device. . For example, when image data displayed in a display connected to a general PC is printed out with a color printer, if the print processing is executed without considering anything, it can be expressed between devices Since the color gamuts are different, the output printed matter is greatly different from the color of the original image data.

Therefore, for the purpose of solving and improving such a problem of color expression, the color information of the output target image data generated by the image generation apparatus and the input apparatus is changed to a device-independent color that does not depend on a specific device. There is already known a technique called gamut conversion (gamut mapping) for converting into colors in a color space that can be reproduced by an output device that expresses in space and outputs image data. Here, the above-described device-independent color space is, for example, the L ^* a ^* b ^* color system.

  The gamut conversion is a process of converting each pixel constituting image data to be output into a color gamut reproducible in the output device, that is, compressing the color gamut. Therefore, when outputting an image in which color is important, a process is required in which an operator visually confirms a change in color before and after gamut conversion.

  As such a technique, the output target image data is compared with an output profile indicating a color gamut reproducible in the output device, and among the pixels included in the output target image data, the output device cannot reproduce. A method of displaying a preview so that an operator can discriminate pixels in the color gamut has been proposed (see, for example, Patent Document 1).

  In the process of visually confirming the change in color before and after the gamut conversion as described above, it is possible to easily grasp which part changes to what extent with respect to the color of the image data to be output. Confirmation method and confirmation screen are desired. However, in the invention disclosed in Patent Document 1, although it is possible to confirm which part of the image data to be output changes, it is not possible to confirm how much it changes.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to facilitate confirmation of how much the color of which part of an output target image has changed before and after gamut conversion.

  In order to solve the above-described problem, an aspect of the present invention is an image processing apparatus that generates image information that is referred to when an image output apparatus outputs an image by converting an output target image. An image acquisition unit that acquires an image of a target, and a visual numerical system image that converts the acquired output target image into an information format expressed by a visual numerical system that is a numerical system of color representation according to human vision A conversion unit, a color gamut compression unit that compresses an output target image expressed in the visual numerical system so as to be expressed in a color within a color gamut reproducible by the image output device, and the visual numerical value A color change amount calculation unit that obtains a difference in numerical value expressing the color of a corresponding pixel between the output target image expressed in the system and the compressed output target image, and each of the pixels constituting the output target image The difference between the values calculated for the vertical direction Of the value, characterized in that it comprises a color variation amount display information generation unit for generating and outputting information for displaying a three-dimensional graph position of the pixel as the horizontal direction value.

  Another aspect of the present embodiment is an image processing program for generating image information to be referred to when an image output apparatus outputs an image by converting the image to be output, A step of acquiring, a step of converting the acquired image to be output into an information format expressed by a visual numerical system, which is a numerical system of color expression according to human vision, and the visual numerical system. A step of compressing the output target image so as to be expressed in a color within a color gamut reproducible by the image output device, and the output target image expressed in the visual numerical system and the compressed Calculating a difference between numerical values representing colors of corresponding pixels in an output target image; and calculating a difference between the numerical values calculated for each of the pixels constituting the output target image as a vertical value, Water position Characterized in that and a step of generating and outputting the information for displaying a three-dimensional graph as the direction of the value to the information processing apparatus.

  According to still another aspect of the present embodiment, there is provided an image processing method for generating image information to be referred to when an image output apparatus outputs an image by converting the output target image, the output target image Is acquired and stored in a storage medium, and the stored output target image is converted into an information format expressed by a visual numerical system that is a numerical system of color expression according to human vision and stored in the storage medium The image to be output expressed in the visual numerical system is compressed and stored in a storage medium so as to be expressed in a color within a color gamut reproducible by the image output device, and the visual numerical system The image of the output target expressed in (1) and the compressed image of the output target are read from the storage medium, the difference between the numerical values expressing the colors of the corresponding pixels is obtained, stored in the storage medium, and the output target image Before calculated for each of the pixels comprising The numerical difference and vertical values, and outputs to generate information for displaying a three-dimensional graph position of the pixel as the horizontal direction value.

  According to the present invention, it is possible to facilitate confirmation of how much the color of which portion of the image to be output has changed before and after gamut conversion.

It is a figure which shows the operation | use form of the image processing system which concerns on embodiment of this invention. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the function structure of the controller terminal which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the image adjustment part which concerns on embodiment of this invention, and the information processed. It is a figure which shows the concept of the gamut compression which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the height information generation part which concerns on embodiment of this invention. It is a figure which shows the example of the output target image processed in embodiment of this invention. It is a figure which shows the example of the L ^* a ^* b ^* data before compression which concerns on embodiment of this invention. It is a figure which shows the example of the L ^* a ^* b ^* data after compression which concerns on embodiment of this invention. It is a figure which shows the example of the contour-line data based on embodiment of this invention. It is a flowchart which shows operation | movement of the gamut inside / outside determination part which concerns on embodiment of this invention. It is a figure which shows the color non-reproducible area | region data which concern on embodiment of this invention. It is a flowchart which shows operation | movement of the image integration part which concerns on embodiment of this invention. It is a figure which shows the example of the contour-line image data which concerns on embodiment of this invention. It is a figure which shows the example of the image displayed based on the contour-line image data which concerns on embodiment of this invention. It is a figure which shows the example of the binary image produced | generated based on the color non-reproducible area | region data which concern on embodiment of this invention. It is a figure which shows the example of the preview image which concerns on embodiment of this invention. It is a figure which shows the example of the preview image which concerns on embodiment of this invention. It is a figure which shows the example of the preview image which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the image adjustment part which concerns on other embodiment of this invention, and the information processed.

Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, an image forming system for commercial printing is taken as an example, and an image to be imaged and output (hereinafter referred to as an output target image) by a general-purpose information processing apparatus such as a PC (Personal Computer) is acquired and the image is acquired. An example will be described in which color conversion corresponding to the color gamut characteristics of the forming apparatus is executed, and image data converted into an image forming output format such as CMYK (Cyan Magenta Yellow black K) is input to the image forming apparatus. .

  FIG. 1 is a diagram illustrating an operation mode of the image forming system according to the present embodiment. As shown in FIG. 1, the image forming system according to the present embodiment includes an image forming apparatus 1, a controller terminal 2, a file server 3, and a digital camera 4. The image forming apparatus 1, the controller terminal 2, and the file server 3 are connected via a network as shown in FIG.

  The image forming apparatus 1 is an apparatus including an image forming engine such as an ink jet method or an electrophotographic method, and outputs an image on a sheet based on image data transmitted from the controller terminal 2. The controller terminal 2 is configured by an information processing device such as a PC, and acquires image data to be imaged and output as described above, and performs image processing such as color matching. In addition, the controller terminal 2 according to the present embodiment has a function of displaying a screen on which an operator can easily check a change in color of the image before and after performing the color matching. This is one of the configurations according to the gist of the present embodiment. This will be described in detail later.

  The file server 3 is configured by an information processing device similarly to the controller terminal 2 and provides a storage area accessible via a network. In the present embodiment, the file server 3 stores image data that can be an output target image, and functions as an image input device that provides an output target image in response to an access from a controller terminal. The digital camera 4 is an image information photographing device, and functions as an image input device that provides the controller 2 with image data that can be an output target image, like the file server 4. As an apparatus operable as an image input apparatus, there may be a scanner or the like in addition to the file server 3 and the digital camera 4 shown in FIG.

  Next, the hardware configuration of the controller terminal 2 according to the present embodiment will be described. FIG. 2 is a block diagram showing a hardware configuration of the controller terminal 2 according to the present embodiment. As shown in FIG. 2, the controller terminal 2 according to the present embodiment has the same configuration as an information processing terminal such as a general server or a PC (Personal Computer).

  The controller terminal 2 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only Memory) 30, an engine 40, an HDD (Hard Disk Drive) 50, and an I / F 60. 90 is connected. Further, an LCD (Liquid Crystal Display) 70 and an operation unit 80 are connected to the I / F 60. Note that the image forming apparatus 1 according to the present embodiment includes an engine that executes image formation in addition to the configuration shown in FIG.

  The CPU 10 is a calculation means and controls the operation of the entire controller terminal 2. The RAM 20 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 30 is a read-only nonvolatile storage medium and stores a program such as firmware. The engine 40 is a mechanism that actually executes image formation in the controller terminal 2.

  The HDD 40 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like. Further, the HDD 40 according to the present embodiment stores information to be referred to when the controller terminal 2 executes image processing. This will be described in detail later.

  The I / F 60 connects and controls the bus 80 and various hardware and networks. The LCD 70 is a visual user interface for the user to check the state of the controller terminal 2. The operation unit 70 is a user interface such as a keyboard and a mouse for the user to input information to the controller terminal 2.

  In such a hardware configuration, a program stored in a recording medium such as the ROM 30, the HDD 40, or an optical disk (not shown) is read into the RAM 20, and operates according to the control of the CPU 10, thereby configuring a software control unit. A functional block that realizes the function of the controller terminal 2 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

  Next, the functional configuration of the controller terminal 2 according to the present embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing a functional configuration of the controller terminal 2 according to the present embodiment. As shown in FIG. 3, the controller terminal 2 according to the present embodiment includes a controller 200 and a network I / F 210 in addition to the HDD 40, the LCD 60, and the operation unit 70 described in FIG. 2. The controller 200 includes a network control unit 201, a display control unit 202, an operation control unit 203, and an image adjustment unit 220.

  The network I / F 210 is an interface for the controller terminal 2 to communicate with other devices via the network, and uses an Ethernet (registered trademark) or a USB (Universal Serial Bus) interface. The network I / F 210 is realized by the I / F 50 shown in FIG.

  The controller 200 is configured by a combination of software and hardware. Specifically, a program stored in a nonvolatile storage medium such as the ROM 30 and the nonvolatile memory and the HDD 40 and the optical disk is loaded into a volatile memory (hereinafter referred to as a memory) such as the RAM 20, and the CPU 10 performs an operation according to the program. The controller 200 is configured by a software control unit configured by performing and hardware such as an integrated circuit. The controller 200 is a control unit that controls the controller terminal 2.

  The network control unit 201 acquires information input via the network I / F 210 and transmits information to other devices via the network I / F 210. The display control unit 202 causes the LCD 60 to display the state of the controller terminal 2 such as a GUI (Graphical User Interface) of the image adjustment unit 220. The operation control unit 203 acquires a signal of an operation by the user with respect to the operation unit 70 and inputs it to software that operates on the controller terminal 2 such as the image adjustment unit 220.

  The image adjustment unit 220 is configured by the CPU 10 performing calculations according to the application program read into the RAM 20, and converts the information format of the output target image when the image forming apparatus 1 executes image formation output. The color gamut is converted so that the color of the image output by the image forming apparatus 1 is more faithful to the color of the output target image. The image adjustment unit 220 converts the color gamut based on an output profile indicating the color characteristics of the image formation output by the image forming apparatus 1. As shown in FIG. 3, the image adjustment unit 220 includes an image conversion processing unit 221 and a comparison result processing unit 222.

  Next, functions of the image conversion processing unit 221 and the comparison result processing unit 222 included in the image adjustment unit according to the present embodiment will be described in detail with reference to FIG. FIG. 4 is a block diagram illustrating the functional configuration of the image conversion processing unit 221 and the comparison result processing unit 222 according to the present embodiment and the format of image data generated by each function.

As shown in FIG. 4, RGB (Red Green Blue) data, which is information of an output target image, is first input to the image conversion processing unit 221. When RGB data is input to the image conversion processing unit 221, the L ^* a ^* b ^* conversion unit 223 converts the RGB data into L ^* a ^* b ^* data based on the input profile stored in the HDD 40. The L ^* a ^* b ^* data is data expressed by the L ^* a ^* b ^* color space, which is a numerical system for color expression according to human vision. The L ^* a ^* b ^* conversion unit 223 It functions as an image acquisition unit and also functions as a visual numerical system image conversion unit.

The input profile is information for converting an image expressed in the RGB color space into an image expressed in the L ^* a ^* b ^* color space. That is, the input profile according to the present embodiment is information of a lookup table in which color values expressed in RGB format and color values expressed in L ^* a ^* b ^* format are associated with 1: 1. It is.

^Here, L ^* a * ^{b *} conversion unit 223 ^{L * a} * ^b * conversion processing by the color range and the pixels included in the RGB data is input, the image forming apparatus 1 though the color gamut representable It is information for simply converting the RGB format to the L ^* a ^* b ^* format. ^That, L ^* a * ^{b * L} * ^a * ^{b *} data generated by the conversion unit 223 is a device-independent ^L * ^a * ^{b *} data, before compression before the gamut compression is performed ^L * a ^* B ^* Data.

^{L *} a ^* b ^* L ^* generated by the conversion unit 223 ^a * ^{b *} data are then inputted to the gamut compression unit 224. The gamut compression unit 224 gamut compresses the pre-compression L ^* a ^* b ^* data based on the output profile. The gamut compression is limited to a color gamut that the image forming apparatus 1 can express device-independent L ^* a ^* b ^* data according to a color gamut that can be expressed by the image forming apparatus 1 that executes image formation output. L ^* a ^* b ^* data, that is, a process of converting into L ^* a ^* b ^* data dependent on the device. That is, the gamut compression unit 224 functions as a color gamut compression unit.

FIG. 5 is a diagram illustrating the concept of gamut compression. In FIG. ^5, is expressed by ^{L * a * b * a *} b * That among the coordinates orthogonal chrominance components. A indicated by a solid line in FIG. 5 is a frame indicating the apparatus-independent L ^* a ^* b ^* color space, that is, the entire L ^* a ^* b ^* color space. On the other hand, B indicated by a broken line in FIG. 5 is a color gamut reproducible by the image forming apparatus 1 in the entire L ^* a ^* b ^* color space in the image forming apparatus 1.

  As shown in FIG. 5, not only the image forming apparatus 1 but a general image forming apparatus cannot reproduce all colors in the color space. Therefore, when the image forming output is executed by the image forming apparatus, it is necessary to convert the color included in the output target image so that it falls within the color range reproducible by the image forming apparatus 1. That is, the process of converting the image represented by the range A in FIG. 5 into the image represented by the range B in FIG. 5 is the gamut compression process.

Therefore, output profile gamut conversion unit 224 references the device independent L ^* a ^* b ^* color values expressed by the format, the image forming apparatus 1 is restricted to the color gamut representable L ^* a ^* B ^* Information of a look-up table associated with a color value in the color space. Gamut compressing unit 224, by referring to such a look-up table, the pre-compression ^L * ^a * ^{b *} data by the gamut compression to produce a post-compression ^L * ^a * ^{b *} data.

  Note that the gamut compression unit 224 adjusts the processing content of the gamut compression in accordance with the parameters input from the gamut adjustment unit 225. The gamut adjustment unit 225 inputs parameters to the gamut compression unit 224 in accordance with a signal input from the operation control unit 203 in response to an operation on the operation unit 70 by the operator.

The compressed L ^* a ^* b ^* data generated by the gamut compression unit 224 is then input to the CMYK conversion unit 226. The CMYK conversion unit 226 performs CMYK conversion on the compressed L ^* a ^* b ^* data based on the output profile, and generates CMYK data of the output target image.

Therefore, the output profile referred to by the CMYK conversion unit 226 does not depend on the color space of the image to be output, and simply converts RGB image data into L ^* a ^* b ^* format image data, that is, device-independent. This is information for conversion to L ^* a ^* b ^* data, and color values expressed in RGB format and color values expressed in L ^* a ^* b ^* format are associated with 1: 1. Lookup table information.

  The CMYK data generated by the CMYK conversion unit 226 is transmitted to the image forming apparatus 1 by the network control unit 201 via the network. As a result, the image forming apparatus 1 executes image forming output based on the CMYK data received from the controller terminal 2.

  As described above, the image conversion processing unit 221 according to the present embodiment matches the output target image exchanged in the RGB format in the information processing apparatus such as the PC with the color space that can be reproduced by the image forming apparatus 1. In the above, processing is performed so that image formation is output with a more faithful color, and then converted into information in CMYK format.

On the other hand, the comparison result processing unit 222 analyzes the influence of the gamut compression by the gamut compression unit 224 and generates a screen so that the operator can easily recognize the influence. As shown in FIG. 4, the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data generated by the process of the image conversion processing unit 221 are the height information of the comparison result processing unit 222. In addition to being input to the generation unit 227, pre-compression L ^* a ^* b ^* data and an output profile are input to the gamut inside / outside determination unit 228.

The height information generation unit 227 compares corresponding pixel color values in the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data, and to what extent the color of each pixel is obtained by gamut conversion. The change amount is calculated, and the change amount is converted into height information. The height information generation unit 227 generates contour line data in which each pixel constituting the output target image is configured by height information. That is, the height information generation unit 227 functions as a color change amount calculation unit.

The height information generation unit 227 performs calculation based on a calculation formula for calculating the degree of difference between the pixels of the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data pixels. This formula can be used formula for general color difference, in the present embodiment, for determining the amount of change in color on the basis of the L ^* a ^* b ^* data, L ^* a ^* b ^* It is possible to use an equation that finds the square root of the square of each element of the data. In addition, a CIE 1994 color difference formula, a CIE 2000 color difference formula, or the like may be used as a method for obtaining the amount of change in color.

The gamut inside / outside determination unit determines whether or not the pixels constituting the output target image are colors that can be reproduced in the image forming apparatus 1 based on the pre-compression L ^* a ^* b ^* data and the output profile, and indicates whether or not each pixel can be reproduced. Flag information is generated, and color non-reproducible area data indicating at least an area where color reproduction is not possible among the pixels constituting the output target image is generated. That is, the gamut inside / outside determination unit functions as a reproducibility determination unit.

The image composition unit 229 converts the contour line data generated by the height information generation unit 227 and the color non-reproducible region data generated by the gamut inside / outside determination unit 228 into an image, combines them, and determines which part of the output target image A preview image L ^* a ^* b ^* data indicating how much the color has changed is generated. The image composition unit 229 adjusts the processing content when generating the preview image L ^* a ^* b ^* data according to the parameters input from the preview setting unit 230. The preview setting unit 230 inputs parameters to the image composition unit 229 in accordance with a signal input from the operation control unit 203 in response to an operation on the operation unit 70 by the operator.

Next, the processing content of each unit of the comparison result processing unit 222 will be specifically described. FIG. 6 is a flowchart showing the operation of generating contour line data by the height information generation unit 227. As shown in FIG. 6, the height information generation unit 227 is determined by referring to one corresponding pixel for each of the input pre-compression L ^* a ^* b ^* data and post-compression L ^* a ^* b ^* data. The difference value is calculated based on the calculated formula (S601).

Here, in this embodiment, an image as shown in FIG. 7 will be described as an example of an output target image. As shown in FIG. 8, the pre-compression L ^* a ^* b ^* data of the output target image is associated with information specifying each pixel and an L ^* a ^* b ^* value indicating the color of each pixel. Information. The compressed L ^* a ^* b ^* data converted by the gamut compressing unit 224 has an L ^* a ^* b ^* value of the pre-compressed L ^* a ^* b ^* data as L ^* ′ as shown in FIG. a ^{*'b *} 'is a converted information in value.

As an example of the calculation formula used in the process of S601, a calculation formula for the color difference ΔE can be used. In addition, hue and saturation, that is, a complementary color component in L ^* a ^* b ^* data is ignored, and a method of comparing only by lightness is also conceivable. Furthermore, it is possible to adopt a method such as adopting an arbitrary formula or switching calculation formulas individually for each brightness range.

  After calculating the difference value, the height information generation unit 227 determines whether or not the calculated difference value is within a confirmation range that is a predetermined threshold (S602). Within the confirmation range is a threshold value for determining whether or not to convert the calculated difference value into information in the height direction, that is, whether or not to present the difference value to the operator.

  In general, since the color change within a predetermined range cannot be recognized by human vision, the process can be simplified by ignoring the color change that cannot be recognized by human vision as being outside the confirmation range. . That is, the process of S602 is a process of determining whether the calculated difference value is larger or smaller than a predetermined threshold value.

  As a result of S602, when the calculated difference value is within the confirmation range (S602 / YES), the height information generation unit 227 converts the difference value into height information and generates height information (S603). . On the other hand, when the calculated difference value is outside the confirmation range (S602 / NO), the height information generation unit 227 sets a flag outside the confirmation range indicating that the difference value of the pixel is ignored (S606).

  When the processing in S603 or S606 is completed, the height information generation unit 227 stores the height information generated in S603 or the out-of-check range flag set in S606 in association with the pixel for which the difference value has been calculated and determined. Thus, the contour line data is updated (S604).

  By repeating such processing for all the pixels constituting the output target image (S605 / NO), contour data as shown in FIG. 10 is generated. As shown in FIG. 10, the contour line data according to the present embodiment is information in which each pixel constituting the output target image is associated with height information determined for each pixel or a flag outside the confirmation range. .

FIG. 11 is a flowchart showing an operation of generating color non-reproducible area data by the gamut inside / outside determination unit 228. As shown in FIG. 11, the gamut inside / outside determination unit 228 refers to one pixel for the input pre-compression L ^* a ^* b ^* data and compares it with the output profile. It is determined whether or not the output profile is within the gamut of the output profile as shown in B (S1101). That is, the output profile referred to in S1101 is information indicating a color gamut reproducible by the image forming apparatus 1 in the entire L ^* a ^* b ^* color space as shown in FIG.

  As a result of the determination in S1101, if the target pixel is reproducible in the image forming apparatus 1 (S1102 / YES), the gamut inside / outside determination unit 228 sets a color reproducible flag for the pixel (S1103). On the other hand, when the target pixel is not reproducible in the image forming apparatus 1 (S1102 / NO), the gamut inside / outside determination unit 228 sets a color reproducibility flag for the pixel (S1106).

  When the processing in S1103 or S1106 is completed, the gamut inside / outside determination unit 228 saves the color reproducibility flag set in S1103 or the color reproducibility flag set in S1106 in association with the target pixel, thereby preventing color reproduction. The area data is updated (S1104). By repeating such processing for all the pixels constituting the output target image (S1105 / NO), color non-reproducible area data as shown in FIG. 12 is generated.

  As shown in FIG. 12, the color non-reproducible area data according to the present embodiment associates each pixel constituting the output target image with a color reproducible flag or a color reproducible flag set for each pixel. Information. The color non-reproducible area data according to the present embodiment includes a color reproducible flag and a color non-reproducible flag as shown in FIG. 12, but at least information capable of recognizing a pixel for which the color reproducible flag is set. It ’s fine.

FIG. 13 is a flowchart showing an operation for generating preview image L ^* a ^* b ^* data by the image composition unit 229. As shown in FIG. 13, the image composition unit 229 generates a wire frame based on the contour data input from the height information generation unit 227 (S1301). This wire frame expresses a three-dimensional graph in which a two-dimensional space is constituted by “pixels” shown in FIG. 10 and points corresponding to the value of “height” are plotted in a direction orthogonal to the two-dimensional space. Image data to be processed. The value of "height", since the pre-compression L ^* a ^* b ^* data is a value corresponding to the variation in color and after compression L ^* a ^* b ^* data, generated wire frame thus Then, the amount of color change can be recognized by the height of the wire frame.

  In addition, the image composition unit 229 executes a height / color information conversion process in which the “height” value of the contour data input from the height information generation unit 227 is normalized and converted to a lightness value. (S1302). The processing of S1302 generates contour line image data in which the information specifying each pixel as shown in FIG. 14 is associated with the “lightness” information obtained by converting the “height” information shown in FIG. Is done.

When the contour image data generated as shown in FIG. 14 is displayed as an image, the color of the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data as shown in FIG. A contour image in which the amount of change is expressed by density is displayed. Note that the shaded portion in FIG. 15 is a portion having a high density.

  Further, the image composition unit 229 generates a color non-reproducible area image based on the color non-reproducible area data input from the gamut inside / outside determination unit 228 (S1303). As shown in FIG. 12, the color non-reproducible area image according to the present embodiment is illustrated with “permitted” as black and “impossible” as white based on the “reproducibility” information of the generated color non-reproducible area data. 16 is a monochrome binary image configured as shown in FIG.

Note that the processing from S1301 to S1303 does not have to be performed in the order as shown in FIG. 13, and may be performed in a different order or may be performed in parallel. When the processing up to S1303 is completed, the image integration unit 229 synthesizes the wire frame, contour image, and color non-reproducible region image generated up to 1303 according to the parameters input from the preview setting unit 230, and the preview image L ^{* A *} b ^* data is generated (S1304). Thereby, the generation operation of the preview image L ^* a ^* b ^* data by the image integration unit 229 is completed.

Here, there are a plurality of types of preview image L ^* a ^* b ^* data generated in the present embodiment in accordance with parameters input from the preview setting unit 230. For example, FIG. 17 is an example of an image obtained by superimposing L ^* a ^* b ^* data before compression on corresponding pixels on the wire frame. With the mode shown in FIG. 17, the output target image is displayed by the pre-compression L ^* a ^* b ^* data, and the amount of color change due to gamut compression can be easily recognized as information in the height direction by the wire frame. It is. Incidentally, the pre-compression ^L * ^a * ^{b *} may be superimposed after compression ^L * ^a * ^{b *} data rather than data.

  FIG. 18 is an example of an image obtained by combining the contour line image shown in FIG. 15 with each corresponding pixel on the wire frame. According to the mode shown in FIG. 18, the amount of change in color due to gamut compression is expressed as information in the height direction by a wire frame, and is expressed by brightness by a contour line image. The amount of change can be more easily recognized by the operator.

FIG. 19 is an example of an image in which L ^* a ^* b ^* data before compression is combined with each corresponding pixel on the wire frame and the contour of the non-reproducible area indicated by the non-reproducible area image is highlighted. . In the form shown in FIG. 19, the amount of color change due to gamut compression is expressed as information in the height direction by a wire frame, and a color that cannot be reproduced by the image forming apparatus 1 is displayed in any part of the output target image. Can easily be recognized by the operator.

  When using a non-reproducible region image, a method of displaying a binary image as shown in FIG. 16 in a superimposed manner in addition to highlighting a non-reproducible region as shown in FIG. There is also a possibility.

  As shown in FIGS. 17 to 19, since the preview image according to the present embodiment has three-dimensional information, it is possible to arbitrarily adjust the display position, angle, size, and the like. Accordingly, the amount of change in color due to gamut compression may be converted into height information and displayed by the stereoscopic display as shown in FIGS. 17 to 19, or the contour line image as shown in FIG. The binary image as shown may be displayed as it is, that is, by displaying the positions of the pixels constituting the output target image in a plane, the distance interval in the entire image may be accurately grasped. These display settings can be realized by an operator's operation via the preview setting unit 230.

  In addition, it is possible to include arbitrary conditional expressions and threshold values related to the preview display target, such as limiting the difference value range as the display target, in the parameters that can be set via the preview setting unit 230.

The preview image L ^* a ^* b ^* data generated as shown in FIGS. 17 to 19 is input to the RGB converter 231. The RGB conversion unit 231 converts the data in the L ^* a ^* b ^* format into the data in the RGB format according to the color expression characteristics of the LCD 60 of the controller terminal 2, and generates preview image RGB data. That is, the RGB conversion unit 231 displays a preview image generated based on pre-compressed L ^* a ^* b ^* data expressed in a device-independent color space on a color space that can be expressed by the LCD 60 of the controller terminal 2. Is converted into RGB data expressed by That is, the monitor profile is a look in which color values expressed in the device-independent L ^* a ^* b ^* format are associated with color values in the RGB color space limited to the color gamut that the LCD 60 can express. It is information of the up table.

  As described above, in the present embodiment, the three-dimensional information generated by the image composition processing by the image composition unit 229 is displayed through the processing by the RGB conversion unit 231. That is, the image composition unit 229 and the RGB conversion unit 231 work together to function as a color change amount display information generation unit.

  The preview image RGB data generated and output in this way is input to the display control unit 202. Then, the display control unit 202 controls the LCD 60 to display the preview image RGB data input from the image adjustment unit 220.

  As described above, in the image processing system according to the present embodiment, as shown in FIGS. 17 to 19, the amount of change in color before and after gamut conversion is extracted, and this is three-dimensionally expressed and visualized. Thus, it can be shown so that it can be easily understood how much the color of which part of the output target image has changed. This makes it possible to provide the operator with more objective judgment materials in the color change confirmation work that could only be judged by the operator's subjectivity.

In the present embodiment, the extraction process of the color change amount by the height information generation unit 227 is executed based on the image expressed by the L ^* a ^* b ^* data. Since the L ^* a ^* b ^* data is a numerical system of color expression according to human vision, the calculation of the color change amount is executed based on the image expressed by the L ^* a ^* b ^* data. Accordingly, it is possible to calculate the amount of change in color according to the perception of color by a person. Note that the calculation of the amount of change in color is based on the L ^* a ^* b ^* data, which is one example. If the numerical system is a color expression according to human vision, the same effect as above It is possible to obtain

  Further, the CMYK conversion by the CMYK conversion unit 226 is performed after the output execution command operation after the preview image is confirmed by the operator, so that the operation of the image forming apparatus 1 can be made efficient. For example, when the image forming apparatus 1 executes the output, paper, ink, toner, and the like are consumed. However, by confirming the preview image according to the present embodiment and executing the output, the unnecessary consumption is reduced. This can reduce the running cost.

As described above, in the present embodiment, the output profile has three roles. That is, the gamut compression unit 224, the device independent of the ^L * ^a * ^{b *} before compression is data of ^L * ^a * ^{b *} data device dependent ^L * ^a * ^{b *} after compression is data ^L * ^a * b ^* Output profile as a first role to be referred to for conversion into data, and CMYK conversion unit 226 as a second role to be referred to in order to convert L ^* a ^* b ^* data after compression into CMYK data The output profile and the gamut inside / outside determination unit 228 refer to determine whether each pixel constituting the pre-compression L ^* a ^* b ^* data is included in the gamut space that can be reproduced by the image forming apparatus 1. This is an output profile as a third role.

  The output profiles having these three types of roles are information generated according to the color characteristics of the image forming apparatus 1 and are stored in the HDD 40. If these three types of roles are distinguished from each other, the first role is a role as a gamut compression profile, that is, as color gamut compression information. The second role is a role as a CMYK conversion profile. The third role is a gamut inside / outside determination profile, that is, a role as reproducible color gamut information. In addition to this output profile, the monitor profile shown in FIG.

  Further, in the above-described embodiment, as described with reference to FIG. 1, the case where the controller terminal 2 and the image forming apparatus 1 are connected via a network has been described as an example. In addition, for example, the controller terminal 2 and the image forming apparatus 1 may be connected by a dedicated interface such as serial connection.

  In the above embodiment, as shown in FIG. 1, the image forming apparatus 1 that prints an image on a sheet as an image output apparatus that finally outputs an image has been described as an example. In addition, the output form of the image may be a display output such as the LCD 60 in addition to the print output. As with the image forming apparatus 1, the LCD 60 is difficult to output all the colors in the actual color space, and the reproducible color gamut is limited. Therefore, according to the above-described aspect, when the LCD 60 displays and outputs an image, the operator can confirm the conversion of the color of the image to be displayed.

  Therefore, the controller terminal 2 according to the present embodiment generates not only the image forming apparatus 1 but also various images output devices such as the LCD 60 by converting the output target image for image output. It functions as an image processing device.

  In the above embodiment, as an example, the terminal that executes the processing according to the gist of the present embodiment and the image output apparatus are realized by different apparatuses, such as the controller terminal 2 and the image forming apparatus 1. explained. In addition, the function of the image adjustment unit 220 shown in FIG. 3 is realized in the image forming apparatus 1, and information such as an input profile, an output profile, and a monitor profile is stored in the HDD 40 of the image forming apparatus 1. It can also be realized by a device.

Embodiment 2. FIG.
In the first embodiment, the case where the output profile referred to by the gamut compression unit 224, that is, the gamut compression profile that is the first role described above is described as an example. However, depending on the image forming apparatus 1, a plurality of gamut compression profiles may be used depending on the colors included in the output target image. In the present embodiment, a case where such an image forming apparatus 1 is used will be described as an example.

  FIG. 20 is a block diagram illustrating a functional configuration of the image conversion processing unit 221 and the comparison result processing unit 222 according to the present embodiment and a format of image data generated by each function. As shown in FIG. 20, the image conversion processing unit 221 has substantially the same configuration as the aspect according to the first embodiment described in FIG.

However, the post-compression L ^* a ^* b ^* data generated by the gamut compression unit 224 is not input to the CMYK conversion unit 226, and the comparison result processing unit 222 sends the conversion unit L ^* a ^* b ^* to the CMYK conversion unit 226 ^. The difference from Embodiment 1 is that data is input. Further, as described above, the gamut compression unit 224 according to the present embodiment performs gamut compression a plurality of times based on a plurality of gamut compression profiles, generates a plurality of post-compression L ^* a ^* b ^* data, The result is input to the sequential comparison result processing unit 222.

The comparison result processing unit 222 according to the present embodiment uses post-compression L ^* a ^* b ^* data and pre-compression L ^* a ^* b ^* data generated based on the plurality of gamut compression profiles as described above. After comparison, based on the comparison result, L ^* a ^* b ^* data after compression having the best color reproducibility is selected. As illustrated in FIG. 20, the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data generated by the process of the image conversion processing unit 221 are the feature change amounts of the comparison result processing unit 222. The data is input to the extraction unit 232.

Similar to the height information generation unit 227 of the first embodiment, the feature change amount extraction unit 232 uses the color of the corresponding pixel in the pre-compression L ^* a ^* b ^* data and the post-compression L ^* a ^* b ^* data. The values are compared, and how much the color of each pixel has changed due to gamut conversion, that is, the feature change amount is calculated.

As described above, the L ^* a ^* b ^* data after the compression is sequentially input from the gamut compression unit 224 to the feature change amount extraction unit 232. Therefore, the feature change amount extraction unit 232 performs the above-described calculation of the feature change amount for each of the compressed L ^* a ^* b ^* data that is sequentially input.

The feature change amount calculated by the feature change amount extraction unit 232 is input to the optimum profile determination unit 233 together with the compressed L ^* a ^* b ^* data that is the calculation source. The optimum profile determination unit 233 compares the feature change amounts sequentially input from the feature change amount extraction unit, and the post-compression L ^* a ^* b ^* data is the most pre-compressed L ^* a ^* b ^* data color. Judge whether it is faithful or not and determine the optimal profile. That is, the optimum profile determination unit 233 functions as a compressed image selection unit.

Ideal as by treatment profile determination unit 233, for example, the feature-change amount calculated for each pixel of the post-compression L ^* a ^* b ^* data, and the total after each compression L ^* for each a ^* b ^* data, its Compare the total values. Then, it is determined that the gamut compression profile used for compression of the post-compression L ^* a ^* b ^* data having the lowest total value is the optimum profile.

When the optimal profile determination unit 233 determines the optimal profile as described above, the compressed profile L ^* a ^* b ^* data related to the profile is input to the CMYK conversion unit 226. Accordingly, the CMYK conversion is executed by the CMYK conversion unit 226 as in the first embodiment, and the image formation by the image forming apparatus 1 is executed.

  Thus, in the controller terminal 2 of the image processing system according to the present embodiment, when there are a plurality of types of gamut compression profiles, by comparing the amount of color change before and after gamut compression by each profile, It is possible to easily determine an appropriate profile for the output target image.

  In FIG. 20, only the feature change amount extraction unit 232 and the optimum profile determination unit 233, which are configurations according to the gist of the present embodiment, are described as the configuration of the comparison result processing unit 222. However, the configuration shown in FIG. 20 and the configuration shown in FIG. 4 may all be implemented.

  In this case, with the configuration of FIG. 4, all the previews of the converted images respectively generated by the plurality of gamut compression profiles are displayed, and as a determination material when selecting the profile to be applied with the configuration of FIG. 20. A profile with the least color change can be presented to the operator.

  In addition, with the configuration of FIG. 20, a profile with the least change in color may be determined, and a preview may be displayed only for an image after conversion using the profile. As described above, since the processing by the height information generation unit 227 and the processing by the feature change amount extraction unit 232 are common processing, it is possible to share a module, simplify the processing, and compare the results. The processing unit 222 can be configured efficiently.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Controller terminal 3 File server 4 Digital camera 10 CPU
20 RAM
30 ROM
40 HDD
50 I / F
60 LCD
70 Operation Unit 80 Bus 200 Controller 201 Network Control Unit 202 Display Control Unit 203 Operation Control Unit 210 Network I / F
220 image adjustment unit 221 image conversion processing unit 222 comparison result processing unit 223 L ^* a ^* b ^* conversion unit 224 gamut compression unit 225 gamut adjustment unit 226 CMYK conversion unit 227 height information generation unit 228 gamut internal / external determination unit 229 image synthesis unit 230 Preview setting unit 231 RGB conversion unit 232 Feature amount extraction unit 233 Optimal profile determination unit

JP 2008-219886 A

Claims (12)

An image processing device that generates image information to be referred to when an image output device outputs an image by converting an output target image,
An image acquisition unit for acquiring the output target image;
A visual numerical system image conversion unit that converts the acquired output target image into an information format represented by a visual numerical system that is a numerical system of color expression according to human vision;
A color gamut compression unit that compresses the image to be output expressed in the visual numerical system so as to be expressed in a color within a color gamut range that can be reproduced by the image output device;
A color change amount calculation unit for obtaining a difference between numerical values representing colors of corresponding pixels between the output target image expressed in the visual numerical system and the compressed output target image;
Generate and output information for displaying a three-dimensional graph with the difference between the numerical values calculated for the pixels constituting the output target image as a vertical value and the pixel position as a horizontal value And a color change amount display information generating unit.   The color change amount display information generation unit superimposes and displays either the output target image expressed in the visual numerical system or the compressed output target image on the stereoscopic graph. The image processing apparatus according to claim 1, wherein information for generating the information is generated.   The color change amount display information generation unit converts the difference between the numerical values calculated for each of the pixels constituting the output target image into lightness information of the image, and converts the image represented by the lightness to the three-dimensional image. The image processing apparatus according to claim 1, wherein information to be displayed superimposed on a graph is generated. Reproduction pixels the image output device in the color gamut of the visual numerical system based on reproducible color gamut information indicating a reproducible color gamut, to construct an image of a previous output target the Ru is compressed by the image output device Including a reproducibility determination unit that determines whether or not it is possible,
The color change amount display information generation unit generates information for superimposing and displaying the determination result of the reproducibility of the pixels constituting the output target image by the image output device on the stereoscopic graph. The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. The reproduction determination unit generates a reproduction prohibited area information irreproducible pixel is specified by the image output apparatus among the pixels constituting the image of a previous output target the Ru compressed,
The color change amount display information generation unit superimposes and displays either the output target image expressed in the visual numerical system or the compressed output target image on the stereoscopic graph. The image processing apparatus according to claim 4, wherein information for highlighting pixels that cannot be reproduced by the image output apparatus is generated. The visual numerical system image conversion unit holds a plurality of types of color gamut compression information in which a color gamut color represented by the visual numerical system is associated with a color gamut color that can be reproduced by the image output apparatus. And generating a plurality of the compressed output target images by executing the compression of the output target image a plurality of times based on each of the plurality of types of color gamut compression information,
The color change amount calculation unit compares each of the plurality of compressed output target images with an output target image expressed in the visual numerical system, thereby expressing a color of a pixel constituting the image. Find the difference between
An image to be input to the image output device is selected from among the plurality of compressed output target images based on a difference in numerical values representing the color of the pixel obtained for each of the plurality of compressed output target images. The image processing apparatus according to claim 1, further comprising a compressed image selection unit.   The color change amount display information generation unit planarly displays information for displaying the three-dimensional graph and positions of pixels constituting the output target image based on a signal input according to an operation by a user. The image processing apparatus according to claim 1, wherein information to be displayed is switched and output. The visual numerical system image conversion unit converts the image to be output into an information format expressed by an L * a * b * color space,
The color change amount calculation unit obtains a difference of at least one element in the L * a * b * color space as a difference in numerical values expressing the color of the pixel. The image processing apparatus according to item 1.   The image processing apparatus according to claim 8, wherein the color change amount calculation unit obtains a color difference in the L * a * b * color space as a difference in numerical values expressing the color of the pixel.   The image processing apparatus according to claim 8, wherein the color change amount calculation unit obtains a difference in lightness in the L * a * b * color space as a difference in numerical values expressing the color of the pixel. An image processing program for generating image information to be referred to when an image output apparatus outputs an image by converting an output target image,
Obtaining an image to be output;
Converting the acquired image to be output into an information format represented by a visual numerical system that is a numerical system of color representation according to human vision;
Compressing an output target image expressed in the visual numerical system so that the image is expressed in a color within a color gamut reproducible by the image output device;
Obtaining a difference between numerical values representing colors of corresponding pixels in the output target image expressed in the visual numerical system and the compressed output target image;
Generate and output information for displaying a three-dimensional graph with the difference between the numerical values calculated for the pixels constituting the output target image as a vertical value and the pixel position as a horizontal value An image processing program causing an information processing apparatus to execute the step of performing. An image processing method for generating image information to be referred to when an image output apparatus outputs an image by converting an output target image,
Acquiring the image to be output and storing it in a storage medium;
The stored output target image is converted into an information format expressed by a visual numerical system that is a numerical system of color expression according to human vision and stored in a storage medium,
The output target image expressed in the visual numerical system is compressed and stored in a storage medium so as to be expressed in a color within a color gamut reproducible by the image output device,
The output target image expressed in the visual numerical system and the compressed output target image are read from the storage medium, and a numerical value difference representing the color of the corresponding pixel is obtained and stored in the storage medium.
Generate and output information for displaying a three-dimensional graph with the difference between the numerical values calculated for the pixels constituting the output target image as a vertical value and the pixel position as a horizontal value An image processing method.