JP2002344763A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor that maintains the number of gradations and the number of expressed colors of image data, through out before and after image processing is applied to the image data. SOLUTION: A CPU 150 performs a matrix arithmetic operations S for image data GD, carries up the significant digit of a color value of the image data GD, to increase the number of gradations of the image data from an 8-bit gradation into an 18-bit gradation. After the CPU 150 performs gamma correction processing, a matrix arithmetic operation N<-1> M, and inverse gamma correction processing, the CPU 150 restores the number of gradations into the original 8-bit gradation to perform automatic image quality adjustment. As a result, the 8-bit gradation of the original image data GD is maintained in the image processing, and the number of expressed colors of the image data GD can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus and an image processing program for performing image processing on an image file.

[0002]

2. Description of the Related Art At present, image data based on various color spaces is used in image data processing apparatuses such as computers, printers, and digital still cameras. For example, in a computer, image data based on an RGB color space is generally used on the assumption that the image data is output to a monitor. In a digital still camera (DSC), generated image data is compressed and stored in a JPEG format. Therefore, image data based on the YCbCr color space suitable for data compression is used. Therefore, for example, when the image data generated by the DSC is processed by the computer, it is necessary to convert the color space of the image data from the YCbCr color space to the RGB color space.

[0003]

However, when the color space of image data is converted from the first color space (YCbCr) to the second color space (RGB), they are arranged at equal intervals in the first color space. Since the color values may not always be arranged at equal intervals in the second color space, the number of tones (number of colors) of the converted image data is equal to the number of tones (number of colors) of the image data before conversion. There was a problem that it decreased compared with. When the number of gradations decreases, the number of colors that can be reproduced decreases, so that the color of the image data cannot be accurately represented, and a problem occurs in that only an output image having a gradation jump is obtained.

The present invention has been made to solve the above problems, and has as its object to maintain the number of gradations and the number of colors of image data before and after image processing conversion.

[0005]

Means for Solving the Problems and Their Functions and Effects In order to solve the above problems, a first aspect of the present invention provides an image processing apparatus for executing image processing on image data. An image processing apparatus according to a first aspect of the present invention is a color system in a first color coordinate system, which converts image data of a first color system capable of expressing a first number of colors into a first color system. The first color number is converted into image data of a second color system, which is a color system in a second color coordinate system and is capable of expressing a second color number larger than the first color number. A color conversion unit that performs conversion by a matrix operation while holding the image data; an image processing unit that performs image processing on the converted image data in the second color system; A color number reduction unit configured to reduce the number of colors.

[0006] According to the image processing apparatus of the first aspect of the present invention, the image data of the first color system capable of expressing the first number of colors in the first color coordinate system is converted to the second image data. A second color number larger than the first color number in the color coordinate system can be converted into image data of a second color system capable of expressing by a matrix operation while maintaining the first color number. Therefore, even when the color conversion processing is executed between different color coordinate systems, the number of gradations and the number of colors of the image data can be maintained before and after the color conversion processing (image processing).

In the image processing apparatus according to the first aspect of the present invention, the image processing executed by the image processing means may include a gamma correction process, and performs color conversion using a second matrix operation. Processing may be included.

In the image processing apparatus according to the first aspect of the present invention, the first color system may be a YCC color system, and the second color system may be an sRGB color system. Alternatively, the first color system is a YCC color system, and the second color system is a YCC color system.
Has a wider color gamut than the sRGB color system.
An RGB color system may be used. In any case, the first number of colors is maintained even after the color conversion. In particular, when the wRGB color system is used, it is possible to color even negative color values that are not expressed by the sRGB color system. it can.

In the image processing apparatus according to the first aspect of the present invention, the second number of colors of the second color system is changed from the first color system to the second color number by the color conversion means. The number of colors represented by negative values included in the image data converted into the color system may be included. In such a case, the first
Even if the image data converted from the color system of the above to the second color system contains a negative value, it is possible to perform colorimetry without losing the color value represented by the negative value. it can.

[0010] A second aspect of the present invention provides an image processing apparatus for executing image processing on image data. The image processing device according to the first aspect of the present invention is configured to set the color value of the image data represented by an integer having a first significant digit to a number of digits greater than the number of the first significant digit. First image processing means for changing to a first value having, and gradation number reduction preventing means for preventing a decrease in the number of gradations of the image data due to a change in color value by the first image processing means; A second image processing unit for changing a color value of the image data having the first value from the first value to a second value reflected in an image output result.

According to the image processing apparatus according to the second aspect of the present invention, it is possible to prevent a decrease in the number of gradations of image data due to a change in color value to the first value, and to reduce the number of image data having the first value. The color value of the data is changed from the first value to the second value reflected in the image output result.
, The number of gradations and the number of expression colors of the image data can be maintained before and after the image processing conversion.

In the image processing apparatus according to a second aspect of the present invention, the means for preventing a decrease in the number of gradations converts the significant digit of the first value to a digit number greater than the digit number of the first significant digit. The setting may prevent a decrease in the number of gradations of the image data. In such a case, even when the integer values having a plurality of different first significant figures take the same first value, the number of significant digits increases, so that the original gradation number is maintained. be able to. The data size of the image data whose gradation number is prevented from being reduced by the gradation number reduction preventing means may be larger than the data size of the image data represented by the integer having the first significant figure. good.
Since the number of significant digits of the image data increases, the data size of the image data increases.

In the image processing apparatus according to a second aspect of the present invention, the first image processing means converts a color space of the image data from a first color space to a second color space. Means may be used. Further, the color space conversion means converts the color space of the image data from the YCbCr color space to R
The image data may be converted to a GB color space, and a color value of the image data represented by an integer having the first significant figure may be changed to the first value including a decimal point. By increasing the number of significant figures, the number of tones can be maintained even when the first value includes a decimal point.

According to a third aspect of the present invention, there is provided an image processing apparatus for executing image processing on image data. The image processing device according to a third aspect of the present invention increases the number of gradations of the image data from the first number of gradations to the second number of gradations, and changes the color space of the image data from the YCbCr color space. sR
First color space conversion means for converting to a GB color space, gamma correction means for performing gamma correction processing on the image data whose color space has been converted, and color of the image data having been subjected to the gamma correction processing Space from sRGB color space to sRG
A second color space conversion unit for converting the image data into a wRGB color space having a definition area wider than the B color space, and a gradation number of the image data obtained by converting the color space from the second gradation number to the first color number. And a gradation number reducing means for returning to the number of gradations.

According to the image processing apparatus of the third aspect of the present invention, the color space of the image data is increased while increasing the number of gradations of the image data from the first number of gradations to the second number of gradations. YCbC
Since the conversion is performed from the r color space to the sRGB color space, the number of gradations and the number of expression colors of the image data can be maintained before and after the image processing conversion.

The image processing apparatus according to a third aspect of the present invention further comprises an inverse gamma correction unit for performing an inverse gamma correction process on the image data whose color space has been converted, and the gradation number reducing unit. May return the gradation number of the image data on which the inverse gamma correction has been performed from the second gradation number to the first gradation number instead of the image data in which the color space is converted. . In such a case, the gradation accuracy in the inverse gamma correction processing can be maintained or improved.

The image processing apparatus according to a third aspect of the present invention further comprises image correction means for automatically correcting the image quality of the image data on which the inverse gamma correction has been executed, and wherein the gradation number reduction means comprises: Instead of the image data on which the inverse gamma correction has been executed, the number of gradations of the image data whose image quality has been corrected may be returned from the second number of gradations to the first number of gradations.
In such a case, the gradation accuracy in the image correction processing can be maintained or improved.

According to a fourth aspect of the present invention, there is provided an output device for outputting image data subjected to image processing. A printing apparatus according to a fourth aspect of the present invention includes an image processing apparatus according to any one of the first to third aspects of the present invention, and an output for outputting image data subjected to image processing by the image processing apparatus. Means.

According to the output device of the fourth aspect of the present invention, it is possible to output image data with good gradation.

According to a fifth aspect of the present invention, there is provided an image processing program for executing image processing on image data. An image processing program according to a fifth aspect of the present invention is a colorimetric system in a first color coordinate system, in which image data of a first colorimetric system capable of representing a first number of colors is stored in a first color coordinate system. The first color number is converted into image data of a second color system, which is a color system in a second color coordinate system and is capable of expressing a second color number larger than the first color number. A function of performing conversion by a matrix operation while holding the data, a function of performing image processing on the converted image data in the second color system, and a function of performing color processing on the image data subjected to the image processing. The reduction function is realized by a computer.

According to the image processing program of the fifth aspect of the present invention, the same operation and effect as those of the image processing apparatus of the first aspect of the present invention can be obtained. Further, an image processing program according to a fifth aspect of the present invention includes the image processing program according to the first aspect of the present invention.
In a manner similar to the image processing apparatus according to the aspect, the invention can be realized in various aspects.

According to a sixth aspect of the present invention, there is provided an image processing program for executing image processing on image data. An image processing program according to a sixth aspect of the present invention is a computer-readable storage medium storing an image processing program for setting a color value of the image data represented by an integer having a first significant digit to a number of digits greater than the number of the first significant digit. A first image processing function for changing to a first value, a function for preventing a decrease in the number of tones of the image data due to a change in color value by the first image processing means, and a first value for the first value. Changing the color value of the image data having the following from the first value to the second value reflected in the image output result.
Is realized by a computer.

According to the image processing program of the sixth aspect of the present invention, it is possible to obtain the same functions and effects as those of the image processing apparatus according to the second aspect of the present invention. Further, an image processing program according to a sixth aspect of the present invention provides the image processing program according to the second aspect of the present invention.
In a manner similar to the image processing apparatus according to the aspect, the invention can be realized in various aspects.

A seventh aspect of the present invention provides an image processing program for executing image processing on image data. An image processing program according to a seventh aspect of the present invention increases the number of gradations of the image data from the first number of gradations to the second number of gradations and changes the color space of the image data to YC.
a first color space conversion function for converting from the bCr color space to the sRGB color space, a gamma correction function for performing gamma correction processing on the image data in which the color space has been converted, and the gamma correction processing has been performed. The color space of image data is sR
A second color space conversion function for converting from the GB color space to a wRGB color space having a defined area wider than the sRGB color space, and a gradation number of the image data in which the color space is converted is represented by the second gradation number. And a function of reducing the number of gradations to return to the first number of gradations by a computer.

According to the image processing program of the seventh aspect of the present invention, it is possible to obtain the same functions and effects as those of the image processing apparatus of the third aspect of the present invention. Further, the image processing program according to the seventh aspect of the present invention is the image processing program according to the third aspect of the present invention.
In a manner similar to the image processing apparatus according to the aspect, the invention can be realized in various aspects.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing apparatus according to the present invention will be described below in the following order with reference to the drawings and based on some embodiments. A. Configuration of image processing system: Image file structure: Image processing in image processing apparatus: Other embodiments:

A. Configuration of Image Processing System: The configuration of an image processing system to which the image processing apparatus according to the present embodiment can be applied will be described with reference to FIGS. FIG. 1 is an explanatory diagram illustrating an example of an image processing system to which the image processing device according to the present embodiment can be applied. FIG. 2 is a block diagram illustrating a schematic configuration of a digital still camera capable of generating an image file (image data) output by the image processing apparatus according to the present embodiment. FIG. 3 is a schematic diagram showing an internal configuration of a color printer applicable to the present embodiment. FIG. 4 is a block diagram showing the internal configuration of the control circuit of the color printer 20.

The image processing system 10 includes a digital still camera 1 as an input device for generating an image file.
2. A personal computer PC as an image processing device for executing image processing based on an image file generated by the digital still camera 12 and outputting print image data, and a color as an output device for outputting print image data A printer 20 is provided. As the image processing apparatus, for example, a stand-alone printer may be used in addition to the personal computer PC. As the output device, a monitor 14 such as a CRT display or an LCD display, a projector, or the like may be used in addition to the printer 20. In the following description, a color printer 20 used by being connected to a personal computer PC will be described.
Is used as an output device.

The personal computer PC is a computer of a generally used type, and includes a CPU 150, a CP for executing an image processing program according to the present invention.
A RAM 151 for temporarily storing the calculation results in U150, image data, and the like, and a hard disk drive (HDD) 152 for storing an image processing program are provided.
The personal computer PC has a card slot 153 for mounting a memory card MC, and an input / output terminal 154 for connecting a connection cable from the digital still camera 12 or the like.

As shown in FIG. 2, the digital still camera 12 is a camera that obtains an image by forming light information on a digital device (CCD or photomultiplier tube). As shown in FIG. An optical circuit 121 including a CCD or the like for collecting information, an image acquisition circuit 122 for controlling the optical circuit 121 to acquire an image, an image processing circuit 123 for processing an acquired digital image, and a memory. And a control circuit 124 for controlling each circuit. Digital still camera 12
Saves the obtained image as digital data in a memory card MC as a storage device. The storage format of the image data in the digital still camera 12 is J
Although the PEG format is generally used, other storage formats such as a TIFF format, a GIF format, a BMP format, and a RAW data format may be used.

The digital still camera 12 also sets individual image processing control parameters such as brightness, contrast, exposure correction amount (exposure correction value), white balance, etc., and a plurality of image processing control parameters in advance in accordance with shooting conditions. Selection for setting the set shooting mode
A determination button 126 and a liquid crystal display 127 for previewing a captured image and setting a shooting mode and the like using the selection / determination button 126 are provided.

The digital still camera 12 used in the image processing system 10 stores image processing control information GC of image data as an image file GF in the memory card MC in addition to the image data GD. That is, the image processing control information GC is automatically stored in the memory card MC together with the image data GD at the time of shooting as information automatically constituting the image file GF.

The image file GF generated by the digital still camera 12 is sent to the color printer 20 via, for example, a cable CV, a computer PC, or a cable CV. Alternatively, the memory card MC in which the image file GF is stored in the digital still camera 12 is connected via the computer PC mounted in the memory card slot, or the memory card MC is directly connected to the printer 20. Thus, the image file is sent to the color printer 20. The following description is based on the case where the memory card MC is directly connected to the personal computer PC.

The internal configuration of the image output device used in the present embodiment, that is, the color printer 20, will be described with reference to FIG. The color printer 20 is a printer capable of outputting a color image, for example, cyan (C),
Magenta (M), Yellow (Y), Black (K) 4
This is an inkjet printer that forms an image by ejecting color inks on a print medium to form a dot pattern. Alternatively, it is an electrophotographic printer that forms an image by transferring and fixing a color toner on a print medium. The color inks include, in addition to the above four colors, light cyan (light cyan, LC), light magenta (light magenta, LM), dark yellow (dark yellow, D
Y) may be used.

As shown in the figure, the color printer 20
Print heads IH1 to IH4 mounted on carriage 30
, A mechanism for reciprocating the carriage 30 in the axial direction of a platen 32 by a carriage motor 31, and a mechanism for transporting the cut paper 40 for printing by a paper feed motor 33. And a control circuit 50. The mechanism for reciprocating the carriage 30 in the axial direction of the platen 32 includes a sliding shaft 34 slidably holding the carriage 30 erected in parallel with the axis of the platen 32, and a carriage motor 31.
And a pulley 36 on which an endless drive belt 35 is stretched.

The control circuit 50 controls the operation panel 2 of the printer.
While exchanging signals with the control unit 1, the movements of the paper feed motor 33, the carriage motor 31, and the print heads IH1 to IH4 are appropriately controlled. An ink cartridge INC1 and an ink cartridge INC2 are mounted on the carriage 30. The ink cartridge INC1 contains black (K) ink, and the ink cartridge INC2 contains other inks, that is, three color inks of cyan (C), magenta (M), and yellow (Y). Light cyan (LC), light magenta (LM), dark yellow (D
As described above, the ink of Y) can be stored.

Next, the internal configuration of the control circuit 50 of the color printer 20 will be described with reference to FIG. As shown in the figure, a CPU 51, a PROM
52, RAM 53, peripheral device input / output unit (PIO) 54,
A timer 55, a driving buffer 56 and the like are provided. P
The IO 54 includes a personal computer PC, a carriage motor 31, a paper feed motor 33, and an encoder 3
7 is connected. The drive buffer 56 is used as a buffer for supplying an on / off signal for dot formation to the print heads IH1 to IH4. These are connected to each other via a bus 57 so that data can be exchanged with each other. The control circuit 50 also includes an oscillator 58 that outputs a drive waveform at a predetermined frequency, and a distribution output device 59 that distributes the output from the oscillator 58 to the ink ejection heads IH1 to IH4 at a predetermined timing. The control circuit 50 includes the paper feed motor 33 and the carriage motor 3
The dot data is output to the drive buffer 56 at a predetermined timing while synchronizing with the movement of No. 1.

B. Image File Structure: A schematic configuration of an image file that can be used in the present embodiment will be described with reference to FIG. FIG. 5 is an explanatory diagram conceptually showing an example of the internal configuration of an image file that can be used in the present embodiment. The image file GF according to the present embodiment is, for example, a digital still camera image file format standard (Exif).
Can have a file structure according to The specifications of the Exif file are defined by the Japan Electronic Industry Development Association (JEIDA).

Image file GF as Exif file
Is a JPEG image data storage area 111 for storing JPEG image data, and an auxiliary information storage area 1 for storing various information related to the stored JPEG image data.
12 are provided. The attached information storage area 112 stores image processing control information GC, such as shooting date and time, exposure, shutter speed, white balance, exposure correction amount, and target color space, which is referred to when outputting a JPEG image. The additional information storage area 112 has a JPEG image data storage area 1 in addition to the image processing control information GC.
11, thumbnail image data of a JPEG image is stored in TIFF format. As is well known to those skilled in the art, in the Exif format file,
Tags are used to specify each data, and each data may be referred to by a tag name. Note that terms such as file structure, data structure, and storage area in this embodiment mean an image of a file or data in a state where the file or data is stored in the storage device.

The image processing control information GC is information relating to the image quality when image data is generated (photographed) by an image data generation device such as the digital still camera 12, etc. Alternatively, parameters such as exposure time, ISO sensitivity, aperture, shutter speed, and focal length that can be arbitrarily set by the user, and image processing such as exposure correction amount, white balance, shooting mode, and target color space arbitrarily set by the user It may include control parameters.

The image file GF according to this embodiment is
In addition to the digital still camera 12, an input device (image file generating device) such as a digital video camera and a scanner
Can also be generated by

C. Image processing in image processing apparatus: FIG.
Image processing in a personal computer PC functioning as an image processing apparatus according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing a processing routine of image processing executed in the personal computer PC according to the present embodiment. FIG. 7 is a flowchart showing a processing routine of image processing based on image processing control information GC executed by the personal computer PC. FIG. 8 is an explanatory diagram showing the relationship between image processing and the number of gradations according to the present embodiment. FIG. 9 shows that the color space conversion is performed.
It is explanatory drawing which shows a mode that the number of gradations decreases conceptually. FIG. 10 is an explanatory diagram conceptually showing how the number of gradations can be maintained even by executing the color space conversion by the operation and effect of the present embodiment. FIG. 11 shows a personal computer P
9 is a flowchart illustrating a processing routine of normal image processing executed in C. FIG. 12 is a flowchart showing a processing routine of image data output processing executed by the personal computer PC.

The image file GF generated by the digital still camera 12 is transmitted via a cable or
Personal computer PC via memory card MC
Provided for. The HDD 1 is operated by the user.
When an image data processing application (program) such as a retouch application or a printer driver installed in the
The PU 150 starts reading the image file GF.

Alternatively, by detecting insertion of the memory card MC into the card slot 153 or connection of the digital still camera 12 via a cable to the input / output terminal 154, the CPU 150 automatically executes the image processing application. Start up the image file G
The reading of F may be started.

The CPU 150 is, for example, a memory card M
When the image file GF is read from C, the read image file GF is temporarily stored in the RAM 151, and the image processing control tag is searched in the attached information storage area 112 of the image file GF (step S100). CPU1
When the image processing control tag can be searched for and found (step S110: Yes), the image processing control information GC acquires and analyzes the image processing control information GC written at the time of generating the image data (step S120). The CPU 150 executes image processing based on the analyzed image processing control information GC based on the analyzed image processing control information GC (step S13).
0), end this processing routine.

If the CPU 150 has not been able to search or find the image processing control tag (step S110: N
o), image processing control information GC when generating image data
Image processing that reflects the
Normal image processing (step S140) is executed, and the present processing routine ends.

Image Processing Based on Image Processing Control Information Executed in Personal Computer PC FIG.
This will be described in detail with reference to FIG. Personal computer P
The CPU 150 of C extracts the image data GD from the read image file GF (Step S200). The extracted image data GD is not an original but a copy, and various image processing is performed on the copied image data GD until the image processing is completed.

The digital still camera 12 stores image data as a JPEG file as described above. In the JPEG file, the image data is stored using the YCbCr color space in order to increase the compression ratio. I have. At present, CP of personal computer PC
Since a 32-bit CPU is generally used as U, an 8-bit data size is assigned to each component of image data, for example, each of Y, Cb, and Cr for YCbCr data. , Y, Cb, and Cr can be represented by 256 gradation numbers (color numbers) from 0 to 255. The color values of the Y, Cb, and Cr components are expressed as integer values. When the color values of the components take different integer values, the Y, Cb, and Cr components are 0 to 2 respectively.
It is represented by the number of gradations of 256 of 55. That is, when the number of gradations increases, the data size of the image data always increases.

The concept of the characteristic image processing in this embodiment will be described with reference to FIGS. In this embodiment, in order to maintain the number of gradations (the number of colors) of the original image data GD through the image processing, the CPU 150 carries out a significant digit carry process on the operation result obtained by the matrix operation S. Execute. As described above, when the image data GD is represented by 256 gradations (8-bit gradation) for each of the YCbCr components, as shown in FIG. It takes an integer value of 0 to 3 (0 to 255). However, since the matrix S includes a decimal point in the matrix coefficient, the color value of the converted image data GD does not always take an integer value.
In order to handle such color values of the image data GD as image data, it is necessary to convert the color values into integer values. In order to convert to an integer value, a method is often employed in which the number of significant digits is maintained, rounded to the nearest whole number by, for example, rounding off the decimal part, and only the integer value is treated as a significant digit.

However, when rounding to an integer value is performed while maintaining the number of significant digits, as shown in FIG.
For example, while the number of gradations is 5 before the conversion, the number of gradations is reduced to 3 after the conversion. That is, if the number of significant figures is increased, a plurality of different color values will have the same color value by maintaining the number of significant figures. The S matrix operation is the first processing of the image processing in the present embodiment. If the number of gradations is reduced at this stage, it cannot be correctly recovered by the subsequent processing, and the accuracy of the image processing is reduced. Would. Further, since a decrease in the number of gradations means a decrease in the number of colors, there is also a problem that the number of colors differs (decreases) between the original image data and the image data after image processing. Occurs.

Therefore, in the present embodiment, the number of significant figures of the converted image data GD obtained as a result of executing the matrix S on the image data GD is calculated from the number of significant figures of the original image data GD. Is also increased. That is, when the color value of the original image data GD is one digit, the number of significant digits of the converted image data GD is 1 or more, and the number of significant digits of the converted image data GD is two or more. When the color value is three digits, the number of significant figures is three. Therefore, the number of significant figures of the converted image data GD is four.
That is all. Although it is arbitrarily determined how many significant digits are allowed in the converted image data with respect to the significant digits of the original image data, but in this embodiment,
The number of gradations of the image data for each of the YCbCr and RGB components is increased from 8-bit gradation to 18-bit gradation. At this time, the size of the image data GD also increases from 8 bits to 18 bits.

As a result, the number of gradations becomes 1024 times,
As shown in FIG. 10, the step of the color value in the RGB color space after the conversion is finer than that in the case of FIG. 9, and if the color value is a value up to three digits after the decimal point, the converted image data All color values can be converted to integer values. If the tone value is converted to an integer color value up to three digits after the decimal point, it is possible to prevent a decrease in the tone number, and to maintain the tone number of the original image data through subsequent image processing. be able to. Further, even when a plurality of color values of the converted image data take the same value, the number of gradations becomes 1024 times, so that the number of gradations of each component of the original image data GD is 25.
6 can be easily maintained, and a decrease in the number of colors can be prevented.

The CPU 150 executes a 3 × 3 matrix operation S in order to convert image data based on the YCrCb color space into image data based on the RGB color space (step S210). The CPU 150 increases the number of gradations of the image data GD after the matrix conversion from the 8-bit gradation to the 18-bit gradation as shown in FIG.
To prevent the number of gradations from decreasing. The matrix operation S is an operation expression shown below.

[0054]

(Equation 1)

As a result of the matrix S conversion, the image data (color value) may take a negative value or a positive value of 256 or more (in the case of 8-bit gradation).
Reference numeral 50 keeps these negative values or positive values of 256 or more as they are, and continues the subsequent image processing.

The CPU 150 outputs the RGB signals thus obtained.
Gamma correction is performed on the image data based on the color space (step S220). When executing the gamma correction, the CPU 150 uses the image processing control information GC
Side gamma value is obtained, a gamma correction table of 18-bit gradation is created in the RAM 151 by using the obtained gamma value in a gamma correction operation expression shown below, and the created gamma correction table is used to generate image data GD. The gamma conversion process is performed for this. That is, the gamma value is also included in the image processing control parameter value specified by the image processing control information GC. The arithmetic expression for gamma correction is as follows.

[0057]

(Equation 2)

The CPU 150 executes a matrix operation (N ^-1 M) for associating the primary color space with the wRGB color space on the image data GD on which the gamma correction has been executed (step S230). The CPU 150 converts the converted image data G obtained by executing the matrix operation (N ^-1 M).
As in the case of the matrix operation S, the number of gradations of D is increased from an 18-bit gradation to a 32-bit gradation by a carry process to prevent a decrease in the number of gradations, as shown in FIG. . Since the image file GF used in the present embodiment in the matrix calculation can include color space information at the time of image generation, if the image file GF includes color space information, the CPU 150 executes the matrix calculation (N ^When executing ( ^-1 M), a matrix operation is executed by using a matrix (N ^-1 M) corresponding to the color space at the time of image generation with reference to the color space information.

The matrix operation (N ⁻¹ M) includes a matrix operation M using a matrix M for converting an RGB color space into an XYZ color space, and a matrix operation using a matrix N for converting a wRGB color space into an XYZ color space. This is a composite matrix of the operation N and the inverse matrix operation N- ¹ .
The matrix M is image data that is not included in the color gamut of the sRGB color space but is effective as data (negative color values)
Is maintained, image data based on the RGB color space is converted into XY
It is a matrix for converting into image data based on the Z color space. The matrix values of the matrix M are determined according to the color space information. Inverse matrix N of matrix N
Converts the image data converted into the image data based on the XYZ color space by the matrix operation M into the wRGB color space having a defined area wider than the sRGB color space (RGB
(Return to color space). The XYZ color space is one of the device-independent color spaces that does not depend on the output characteristics of the device, and is used to associate color values between the RGB color space and the wRGB color space. The matrix operation (N ^-1 M) is an operation expression shown below.

[0060]

(Equation 3)

The color space of the image data GD obtained after the execution of the matrix operation (N ⁻¹ M) is a wRGB color space having a wider defined area than the sRGB color space. conventionally,
The color space used for image processing in a printer or a computer is fixed to sRGB, and even if the printer has a color gamut that is larger than the sRGB color space and includes the color gamut of the digital still camera 12, digital still The color space of the camera 12 cannot be used effectively. On the other hand, in the present embodiment, when the color space information is included in the image file GF, the matrix (N ⁻¹ M) used for the matrix operation M is changed in accordance with the color space information. In addition, the color space of the digital still camera 12 can be effectively utilized to realize correct color reproduction.

The CPU 150 executes a matrix operation (N
Inverse gamma correction is performed on the image data obtained by ( ⁻¹ M) (step S240). As shown in FIG. 8, the CPU 150 changes the number of tones of the image data GD obtained by the matrix operation (N ^-1 M) from the 32-bit gray scale to 18 gray scales.
By reducing to bit gradation, the data size is also reduced from 32 bits to 18 bits. The reduction in the number of gradations is performed by extracting the upper 18 bits of the 32-bit image data GD as the image data GD. When performing gamma correction, the CPU 150 acquires a default gamma value on the printer side from the HDD 152 and generates an inverse gamma correction table in the RAM 151 using the reciprocal of the acquired gamma value in the following inverse gamma correction equation. Then, an inverse gamma conversion process is performed on the image data GD using the generated inverse gamma correction table. The arithmetic expression used for the inverse gamma correction is as follows.

[0063]

(Equation 4)

As shown in FIG. 8, the CPU 150 reduces the number of gradations of the image data GD subjected to the inverse gamma correction from the 18-bit gradation to the 8-bit gradation, and changes the data size from 18 bits to 8 bits. To decrease. During the inverse gamma correction process, it is necessary to generate an inverse gamma correction table,
When the number of gradations is large, the required amount of memory resources increases and the calculation process takes time. On the other hand, since the number of gradations recognized by human eyes is about 8-bit gradation for each component, the output result is not affected. The reduction in the number of gradations is performed by extracting the upper 8 bits of the 18-bit image data GD as the image data GD. In the next automatic image quality adjustment, each of the R, G, and B components may be simultaneously processed.
This is because only bit image data can be handled.

The CPU 150 performs an automatic image quality adjustment process on the image data GD on which the inverse gamma correction has been performed (step S250). In the image quality automatic adjustment process in the present embodiment, the image data GD included in the image file GF is analyzed to obtain a characteristic parameter value indicating the image quality, and the image processing control information GC included in the image file GF is obtained. Automatic adjustment of the image quality for correcting the image data by reflecting the characteristic parameter values thus performed is executed. In the image quality automatic adjustment process, a reference parameter to be a correction target is determined in advance, and an image quality correction amount is determined so as to eliminate or reduce a difference between the reference parameter and a characteristic parameter of image data. The image processing control information GC may be used to change the value of the reference parameter, or may be used to change the application level of the image quality correction amount.

In the correction of image data, for example, for brightness, contrast, color balance, etc., each pixel (pixel) is obtained by using a characteristic line which is generally called a tone curve and associates an input level and an output level of an RGB signal.
Executed in units. For example, for saturation, sharpness, noise reduction, and the like, pixel calculation processing (filter processing) is executed in pixel units instead of tone curve processing.

When the CPU 150 finishes the automatic image quality adjustment processing, it outputs the processed image data to the printer driver (step S260), and returns to the processing routine shown in FIG.

Next, the normal image processing executed in the personal computer PC will be described in detail with reference to FIG. Note that, of the processing executed in each step, processing similar to the processing in the extended image processing described with reference to FIG. 7 will be described only briefly. The CPU 150 of the personal computer PC
The image data GD is extracted from the read image file GF (step S300). The CPU 150 is a YCrC
3 × 3 matrix operation S for converting image data based on the b color space into image data based on the sRGB color space
Is executed (step S310). Matrix operation S
Is the operation expression described above.

The CPU 31 executes an automatic adjustment process of the image quality on the image data obtained by the matrix operation S (step S320), and outputs the image data GD after the image processing to the printer driver (step S33).
0), and return to the processing routine shown in FIG.

Referring to FIG. 12, an output process of image data GD, that is, a print control process executed by a printer driver (print control program) will be described. The CPU 150 acquires the image data included in the print job (step S400), and outputs the RGB data for printing.
A CMYK color conversion process is executed (step S410).
Prior to the color conversion process, if the resolution of the image data GD is lower than the printing resolution, linear interpolation is performed to generate new data between adjacent image data. Conversely, if the resolution is higher than the printing resolution, A resolution conversion process for converting the resolution of the image data into the print resolution may be executed by thinning out the data at a fixed rate.

When the result of the image processing on the copy image data GD up to this point is reflected on the original image data GD, it is realized by selecting overwriting of the image data. When the color space set at the time of generating the image data can be obtained from the image file GF, and the set color space is a color space wider than the sRGB color space, for example, a wRGB-CMYK color conversion table Is used and if the image processing control tag cannot be found, s
An RGB-CMYK color conversion table is used. CPU
150 is wRGB stored in the HDD 152
The color space of the image data is changed from the wRGB color space to the CMYK color space with reference to a conversion lookup table (LUT) that associates the color space with the CMYK color space. That is, image data consisting of R, G, B gradation values is used in the color printer 20, for example, C, M, Y, K, LC
・ Convert to gradation value data of each of the six colors of LM.

CPU 150 executes a halftone process (step S420), and terminates this process routine.
In the halftone process, color-converted image data is received, and a tone number conversion process is performed. In this embodiment,
The image data after the color conversion is expressed as data having 256 gradation widths for each color. On the other hand, the color printer 20 according to the present embodiment can take only one of the states “form dots” and “do not form dots”. Only the key can be expressed. Therefore, image data having 256 gradations is
The image data is converted into image data expressed by two gradations that can be expressed by the color printer 20. As a typical method of the binarization (binarization) processing, there is a method called an error diffusion method and a method called an organized dither method. The CPU 150 converts the image data converted into a format representing the presence or absence of dot formation into
An interlace process for rearranging the color printer 20 in the order to be transferred is also executed.

As described above, according to the personal computer PC in this embodiment, the number of gradations and the number of colors of image data can be maintained before and after image processing on the image data GD. As described with reference to FIG. 9, generally, when the color space of the image data GD is converted, the distribution of the color values of the converted image data GD is unevenly spaced, and the color space of the conversion destination is changed. In order to conform to the gradation interval in (integer value conversion), a plurality of color values that were different in the color space before conversion take the same color value in the color space after conversion, and the number of gradations always decreases. I will. On the other hand, in the personal computer PC according to the present embodiment,
When the matrix operation S, which is the first image processing for the image data GD, is executed, the number of gradations (image data size)
Increased from bits to 18 bits (increased number of significant digits)
Thus, it is possible to make it difficult for a plurality of color values different in the color space before conversion to obtain the same color value in the color space after conversion. Further, the number of gradations is changed from 256 to 262144.
Therefore, even if some color values take the same value, 256 gradations can be maintained as a whole. Therefore, 256 gradations, which is the number of gradations of the original image data GD, can be maintained and 1
6,770,000 colors can be maintained.

Further, in this embodiment, the matrix operation S
Maintain the negative color values included in the image data color-converted from the YCbCr color space (color system) to the RGB color space (color system), and convert the converted image data into the generated negative color values. Mapping to the wRGB color space included in the color gamut.
Therefore, it is possible to prevent a color (gradation) that can be represented by a negative color value from being lost, and to prevent a decrease in the number of colors before and after the color conversion. This will be described with reference to FIGS. FIG. 13 is an explanatory diagram conceptually showing a state in which the number of gradations is reduced due to the lack of a negative color value generated by executing the color space conversion. FIG. 14 is an explanatory diagram conceptually showing how the number of tones obtained by negative color values can be maintained even by performing color space conversion by the operation and effect of the present embodiment.

The RGB data obtained by the matrix operation S may include a negative color value. Conventionally, Figure 1
As shown in FIG. 3, the image data obtained after conversion using the matrix S was mapped to a standard sRGB color space. When mapping to the sRGB color space,
A color value outside the color gamut of the sRGB color space, that is, a negative color value is a color value of 256 or more (in the case of 8-bit data)
For example, a process of clipping to a color value of 0,255 has been executed. In such a case, even if the number of gradations is increased, a negative color value, a color value of 256 or more is cut off, so that a negative color value, a gradation represented by a color value of 256 or more, The number of colors could not be maintained. Therefore, in the sRGB color space, the number of gradations (the number of colors), which was 6 in the YCbCr color space, is reduced to 3 in the sRGB color space due to the matrix operation and clipping of negative color values.

On the other hand, in the present embodiment, the image data obtained after conversion using the matrix S is mapped to a wRGB color space having a wider color gamut than the sRGB color space. Therefore, as shown in FIG. 14, a negative color value in the RGB color space becomes a positive color value in the wRGB color space due to a color gamut wider than the sRGB color space. Further, by increasing the number of gradations, it is possible to prevent gradation drop and decrease in the number of colors due to expansion of the color gamut and matrix operation. As a result, in the YCbCr color space, 6
Is maintained also in the wRGB color space, and it is possible to more effectively prevent a gradation drop and a decrease in the number of color specifications predicted by executing the matrix operation S.

F. Other Embodiment: In the above embodiment, the color printer 2 is used in the personal computer PC.
Although the image processing of the image data GD output to the monitor 0 and the monitor 14 has been executed, all the image processing may be executed by the color printer 20. In such a case, the color printer 20 can realize both image processing of the image data GD and printing of the image data GD on which the image processing has been executed. When image processing is performed by the color printer 20, the memory resources that can be used for image processing are limited, so that the increase / decrease value of the number of gradations may be changed. For example, the matrix operation S is performed on the 8-bit grayscale image data GD for each component to obtain an 18-bit grayscale, and the gamma correction process is performed using the upper 11 bits to obtain the 18-bit grayscale. (N ^-1 M) to make a 28-bit gradation,
The automatic image quality adjustment processing may be executed by executing the inverse gamma correction processing using the bits and performing 8-bit gradation. Even in such a case, since the number of tones of the original image data does not return during the image processing, the number of tones is 8 bits in the original image data after the image processing is performed. Is maintained in the image data.

Further, all or a part of the image processing may be executed on a server via a network.

The image processing apparatus, the image processing method, the image processing program, and the image output apparatus according to the present invention have been described based on the embodiments.
This is for the purpose of facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be modified and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

The number of gradations used in the above embodiment is merely an example, and a 32-bit gradation may be held after execution of the matrix operation S until execution of inverse gamma correction. When the number of data bits available in the personal computer PC shifts from 32 bits to 64 bits, a 64-bit gradation may be used instead of the 32-bit gradation. In such a case, gradation drop during image processing can be more effectively prevented. In any case, it is sufficient that the 8-bit gradation of the original image data GD can be maintained until the end of the image processing.

In the above embodiment, the matrix operation (N
^{Although the} number of gradations is reduced after executing ( ⁻¹ M), the number of gradations may be reduced after performing the inverse gamma correction and then performing the automatic image quality adjustment. Further, the number of gradations in this specification is merely an example, and any number of gradations may be used as long as the number of gradations is maintained before and after image processing.

The matrices S, N in each equation
The value of ⁻¹ M is merely an example, and it goes without saying that the value can be changed as appropriate depending on the target color space, the color space available in the color printer 20, and the like.

In the above embodiment, the digital still camera 12 has been described as the image file generating device.
In addition, a scanner, a digital video camera, or the like can be used.

In the above embodiment, an Exif format file has been described as a specific example of the image file GF.
The format of the image file according to the present invention is not limited to this.
That is, any image file containing image data generated by the image data generation device and image processing control information GC describing conditions (information) at the time of generation of the image data may be used. With such a file, the image quality of the image data generated by the image file generation device can be automatically adjusted appropriately and output from the output device.

In the above embodiment, the case where the image data GD and the image processing control information GC are included in the same image file GF has been described as an example. However, the image data GD and the image processing control information GC are not necessarily the same. It does not need to be stored in the file. That is, it is sufficient that the image data GD and the image processing control information GC are associated with each other. For example, association data that associates the image data GD with the image processing control information GC is generated, and one or a plurality of image data and the image processing control are generated. The information GC may be stored in independent files, and the associated image processing control information GC may be referenced when processing the image data GD. In such a case, although the image data and the image processing control information GC are stored in separate files, at the time of the image processing using the image processing control information GC, the image data and the image processing control information GC cannot be integrated. And the function is substantially the same as that in the case of being stored in the same file. That is, the mode in which the image data and the image processing control information GC are used in association with each other at least at the time of the image processing is included in the image file GF in the present embodiment. Furthermore, CD-ROM, CD-R,
Moving image files stored on optical disk media such as DVD-ROM and DVD-RAM are also included.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of an image processing system to which an image processing apparatus according to an embodiment can be applied.

FIG. 2 is a block diagram illustrating a schematic configuration of a digital still camera capable of generating an image file (image data) to be processed by the image processing apparatus according to the embodiment.

FIG. 3 is an explanatory diagram showing a schematic internal structure of an image file stored in an Exif file format that can be used in the present embodiment.

FIG. 4 is a block diagram illustrating a schematic configuration of a color printer 20 according to the present embodiment.

FIG. 5 is an explanatory diagram illustrating an internal configuration of a control circuit 30 of the color printer 20 according to the embodiment.

FIG. 6 is a flowchart illustrating a processing routine of image processing executed in the personal computer PC according to the present embodiment.

FIG. 7 is a flowchart showing a processing routine of image processing based on image processing control information GC executed by a personal computer PC.

FIG. 8 is an explanatory diagram showing a relationship between image processing and the number of gradations according to the embodiment.

FIG. 9 is an explanatory diagram conceptually showing a state in which the number of gradations is reduced by executing color space conversion.

FIG. 10 is an explanatory diagram conceptually showing a state in which the number of gradations can be maintained even by executing color space conversion by the operation and effect of the present embodiment.

FIG. 11 is a flowchart illustrating a processing routine of normal image processing executed by the personal computer PC.

FIG. 12 is a flowchart showing a processing routine of image data output processing executed by the personal computer PC.

FIG. 13 is an explanatory diagram conceptually illustrating a state in which the number of gradations is reduced due to a lack of a negative color value generated by performing color space conversion.

FIG. 14 is an explanatory diagram conceptually showing a state in which the number of tones obtained by negative color values can be maintained even by executing color space conversion by the operation and effect of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Image processing system 12 ... Digital still camera 121 ... Optical circuit 122 ... Image acquisition circuit 123 ... Image processing circuit 124 ... Control circuit 126 ... Selection / decision button 127 ... Liquid crystal display 14 ... Display 150 ... CPU 151 ... RAM 152 ... HDD 153 Card slot 154 Input / output terminal 20 Color printer 21 Operation panel 30 Carriage 31 Carriage motor 32 Platen 33 Paper feed motor 34 Sliding shaft 35 Drive belt 36 Pulley 37 Encoder IH1, IH2 , IH3, IH4 ... print head INC1 ... ink cartridge INC2 ... ink cartridge 50 ... control circuit 51 ... arithmetic processing unit (CPU) 52 ... programmable read only memory (PROM) 53 ... random access memory Re (RAM) 54 ... Timer 55 ... Peripheral device input / output unit (PIO) 56 ... Drive buffer 57 ... Bus 58 ... Oscillator 59 ... Distribution output device GF ... Image file (Exif file) GD ... Image data 111 ... JPEG image data storage Area 112: Auxiliary information storage area MC: Memory card PC: Personal computer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshihiro Nakami 3-5-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation F-term (reference) 5B057 CA01 CA08 CB01 CB08 CE11 CE17 CE18 CH01 CH11 5C077 MP08 PP15 PP32 PP33 PP34 PP37 PQ12 PQ22 RR06 TT09 5C079 HB01 HB03 HB04 HB12 LA12 LA33 LB02 MA01 MA11 NA03 NA05

Claims (28)

[Claims] 1. An image processing apparatus for performing image processing on image data, comprising: a first color coordinate system in a first color coordinate system, wherein a first table capable of expressing a first number of colors is provided. The image data of the color system is converted into image data of a second color system which is a color system in a second color coordinate system and is capable of expressing a second color number larger than the first color number. ,
A color conversion unit that performs conversion by a matrix operation while maintaining the first number of colors; an image processing unit that performs image processing on the converted image data in the second color system; An image processing apparatus comprising: a color number reduction unit configured to reduce a color number of image data to which color image processing is applied. 2. The image processing apparatus according to claim 1, wherein the image processing performed by the image processing unit includes a gamma correction process. 3. The image processing apparatus according to claim 2, wherein the first color system is a YCC color system, and the second color system is an sRGB color system. 4. The image processing apparatus according to claim 1, wherein the second color number of the second color system is changed from the first color system to the second color number by the color conversion unit. An image processing apparatus including the number of colors represented by negative values included in image data converted into a color system. 5. The image processing apparatus according to claim 4, wherein the image processing performed by said image processing means includes a gamma correction process. 6. The image processing apparatus according to claim 4, wherein the image processing executed by the image processing means includes
An image processing apparatus including a color conversion process using a matrix operation. 7. The image processing apparatus according to claim 4, wherein the first color system is a YCC color system, and the second color system is a color gamut wider than an sRGB color system. An image processing apparatus having a wRGB color system. 8. An image processing apparatus for performing image processing on image data, wherein a color value of the image data represented by an integer having a first significant figure is converted to a color value of the first significant figure. First image processing means for changing to a first value having a number of digits greater than the number of digits, and preventing a decrease in the number of gradations of the image data due to a change in color value by the first image processing means. Means for preventing a decrease in the number of gradations, and second image processing means for changing a color value of the image data having the first value from the first value to a second value reflected in an image output result. Image processing device provided. 9. The image processing apparatus according to claim 8, wherein the gradation number reduction preventing unit sets the significant digit of the first value to a digit number greater than the digit number of the first significant digit. An image processing apparatus for preventing a decrease in the number of gradations of the image data. 10. The image processing apparatus according to claim 9, wherein the data size of the image data whose gradation number is prevented from being reduced by the gradation number reduction preventing means is an integer having the first significant figure. An image processing apparatus characterized by being larger than the data size of the image data represented by: 11. The image processing apparatus according to claim 8, wherein said first image processing means changes a color space of said image data from a first color space to a second color space. An image processing apparatus characterized in that the image processing apparatus is a color space conversion unit that converts the image into a color space. 12. The image processing apparatus according to claim 11, wherein the color space conversion unit converts the color space of the image data into YC
An image which is converted from a bCr color space to an RGB color space, and changes a color value of the image data represented by an integer having the first significant figure to the first value including a decimal point. Processing equipment. 13. An image processing apparatus for performing image processing on image data, comprising: increasing the number of tones of the image data from a first number of tones to a second number of tones; Color space of YCbC
a first color space conversion unit for converting an r color space to an RGB color space, a gamma correction unit for performing a gamma correction process on the image data obtained by converting the color space, and the gamma correction process is performed. A second color space conversion means for converting the color space of the image data from the RGB color space to a wRGB color space having a defined area wider than the sRGB color space; The second
An image processing apparatus comprising: a number-of-tones reduction unit that returns the number of levels from the number of levels to the first number of levels. 14. The image processing apparatus according to claim 13, further comprising: an inverse gamma correction unit configured to execute an inverse gamma correction process on the image data whose color space has been converted; Returning the gradation number of the image data on which the inverse gamma correction has been executed from the second gradation number to the first gradation number instead of the image data in which the color space is converted. Image processing device. 15. The image processing apparatus according to claim 14, further comprising: an image correction unit configured to correct an image quality of the image data on which the inverse gamma correction has been performed; An image processing apparatus for returning the number of tones of the image data whose image quality has been corrected from the second number of tones to the first number of tones in place of the image data on which the image processing has been performed. 16. An output device for outputting image data on which image processing has been performed, wherein the image processing device according to any one of claims 1, 8, and 13; An output unit that outputs the processed image data. 17. An image processing program for performing image processing on image data, wherein the first color coordinate system is a color system and the first color number is a first color number. The image data of the color system of the second color coordinate system in the second color coordinate system, the image of the second color system capable of representing a second color number greater than the first color number To the data,
A function of performing conversion by a matrix operation while maintaining the first number of colors; a function of performing image processing on the converted image data in the second color system; and the image processing is performed. An image processing program for realizing, by a computer, a function of reducing the number of colors of image data. 18. The image processing program according to claim 17, wherein the second color number of the second color system is changed from the first color system to the second color number by the color conversion means. An image processing program including the number of colors represented by negative values included in image data converted into a color system. 19. The image processing program according to claim 18, wherein the function of executing the image processing is a function of executing at least one of a gamma correction process and a color conversion process using a second matrix operation. Processing program. 20. The image program according to claim 18, wherein the first color system is a YCC color system, and the second color system has a wider color gamut than an sRGB color system. An image processing program that is a wRGB color system. 21. An image processing program for performing image processing on image data, comprising: converting a color value of the image data represented by an integer having a first significant figure into the first validity value. A first image processing function of changing to a first value having a number of digits greater than the number of digits, and a reduction in the number of gradations of the image data due to a change in color value by the first image processing means. And a second image processing function of changing a color value of the image data having the first value from the first value to a second value reflected in an image output result by a computer. An image processing program to be executed. 22. The image processing program according to claim 21, wherein the prevention of the decrease in the number of gradations sets the significant digit of the first value to a digit number greater than the digit number of the first significant digit. An image processing program characterized by being realized by performing 23. The image processing program according to claim 22, wherein the data size of the image data in which the reduction in the number of gradations is prevented is the data size of the image data represented by an integer having the first significant figure. An image processing program characterized by being larger than a data size. 24. The image processing program according to claim 22, wherein the first image processing function converts a color space of the image data from a first color space to a second color space. An image processing program for realizing a color space conversion function by a computer. 25. The image processing program according to claim 24, wherein the color space conversion function converts a color space of the image data into YC.
An image which is converted from a bCr color space to an RGB color space, and changes a color value of the image data represented by an integer having the first significant figure to the first value including a decimal point. Processing program. 26. An image processing program for performing image processing on image data, comprising: increasing the number of tones of the image data from a first number of tones to a second number of tones; Color space of image data is YCbC
a first color space conversion function for converting from the r color space to the sRGB color space, a gamma correction function for performing gamma correction processing on the image data whose color space has been converted, and the gamma correction processing has been performed. A second color space conversion function for converting the color space of the image data from the sRGB color space to a wRGB color space having a definition area wider than the sRGB color space; Second
An image processing program for causing a computer to realize a function of reducing the number of gradations from the number of gradations to the first number of gradations. 27. The image processing program according to claim 26, further comprising: causing a computer to implement an inverse gamma correction function of performing an inverse gamma correction process on the image data whose color space has been converted; The reduction function is a function of returning the number of tones of the image data on which the inverse gamma correction has been executed from the second number of tones to the first number of tones in place of the image data whose color space has been converted. An image processing program, characterized in that: 28. The image processing program according to claim 27, further comprising: causing a computer to realize an image correction function of automatically correcting the image quality of the image data on which the inverse gamma correction has been performed; Is a function of returning the number of gradations of the image data whose image quality has been corrected from the second number of gradations to the first number of gradations in place of the image data on which the inverse gamma correction has been executed. An image processing program characterized by the following.