JP2007124646A - Output image adjustment for image files - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image output apparatus capable of accurately outputting color space information in image data production. <P>SOLUTION: A CPU 31 of a color printer 20 performs gamma correction and a matrix operation M on RGB color space image data derived from a matrix S operation. The CPU 31 performs gamma conversion on video data using established gamma values. Matrix operation M converts the RGB color space to the XYZ color space. When executing matrix operation M, the CPU 31 refers to a color space tag in order to reflect the matrix operation with color space at the time of image data production and performs the matrix operation using a matrix (M) corresponding to color space written in the file. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing technique involving conversion of image data on a color space.

  Unlike ordinary silver-salt cameras where the output form of general captured images is printing on photographic paper, digital images captured by a digital still camera (DSC) or digital video camera (DVC) or captured by a scanner Data can be easily subjected to image processing. Generally, in DSC or the like, captured image data is often stored as a file in JPEG format, which is one of image compression file formats. In this JPEG format image file, image data is defined using a color space of YCbCr in order to increase the compression rate. Therefore, DSC or the like once converts captured image data defined in the RGB color space into the YCbCr color space using the CCD. Further, the RGB color space handled by the DSC or the like at this time is generally a color space of a CRT monitor (for example, sRGB: IEC619662-1) that is typically used in a personal computer.

JP-A-9-238265 JP-A-11-146182

  On the other hand, since the RGB color space is used as a standard color space for image data in a personal computer, a personal computer that receives such a JPEG file decompresses the JPEG file and changes the color space of the image data to YCbCr. Convert from color space to RGB color space. As described above, the image data thus converted to the RGB color space is handled as, for example, sRGB color space data and displayed on the monitor or converted to the CMYK color space and then transferred to the print medium via the printer. Is printed out.

  However, for example, image processing apparatuses and image output apparatuses such as CRT, LCD, printer, projector, and television receiver have different image output characteristics, for example, color reproduction characteristics (color space). The generated image file is not always output in the correct color in all the output devices described above. For example, when an image file is generated based on image output in a CRT, the color reproduction characteristics of the printer can be fully utilized even if the image file is output by a printer having a color reproduction area wider than that of the CRT. There is a problem that an appropriate image output cannot be obtained. Such a problem is not limited to DSC, but is common to other image file generation apparatuses such as DVC.

  On the other hand, the color space conversion process from the YCbCr color space to the RGB color space based on the sRGB color space characteristics that can be expressed by the CRT monitor is widely performed, and the color space characteristics cannot be easily changed. There's a problem.

  SUMMARY An advantage of some aspects of the invention is that it generates an image file that can correctly reproduce image data in an image processing apparatus and an output apparatus. It is another object of the present invention to provide an image processing apparatus that can accurately process and output color values of image data using such an image file.

  In order to solve the above problems, a first aspect of the present invention provides an image file generation device. An image file generation device according to a first aspect of the present invention associates image data generation means for generating image data, information on a color space used in the image processing device, and the generated image data. And image file generation means for generating an image file to be stored.

  According to the image file generation device according to the first aspect of the present invention, the image file for storing the color space information used in the image processing device and the generated image data in association with each other is generated. Information on the color space to be used can be given to the image processing apparatus. For example, the color space used in the color space conversion process in the image processing apparatus can be specified.

  In the image file generation device according to the first aspect of the present invention, the color space information may be a matrix value used during color space conversion processing executed in the image processing device. In such a case, it is possible to perform color space conversion processing in the image processing apparatus without having to interpret color space information.

The image file generation device according to the first aspect of the present invention further includes:
Color space information designating means for designating color space information used in the image processing apparatus;
Color space information storage means for storing a plurality of color space information that can be designated as the color space information,
The color space information specifying means includes
Display means for displaying the stored color space information;
Selection means for selecting one color space information from the displayed color space information may be provided. When such a configuration is provided, the conversion destination color space can be easily selected.

The image file generation device according to the first aspect of the present invention further includes:
Color space information designating means for designating color space information used in the image processing apparatus;
Color space information storage means for storing a plurality of combinations of identification information for identifying an image processing apparatus that performs image processing on the image file and color space information that can be specified as information on the color space. ,
The color space specifying means includes
Display means for displaying candidate image processing apparatuses for performing image processing;
Selection means for selecting one image processing apparatus from the displayed image processing apparatus candidates may be provided. When such a configuration is provided, a conversion destination color space in the image processing apparatus can be easily selected by selecting the image processing apparatus.

  A second aspect of the present invention provides an image file generation device. An image file generation device according to a second aspect of the present invention includes an image data acquisition unit that acquires image data, a color space specification unit that specifies a destination color space for color space conversion executed in the image processing device, Image file generation means for generating an image file for storing the specified conversion destination color space information and the acquired image data in association with each other.

  According to the image file generation device of the second aspect of the present invention, it is possible to generate an image file that can specify a conversion destination color space used in an image processing device that performs image processing on image data. it can. Therefore, when the image file is subjected to image processing, the color space of the image data can be converted into a color space suitable for the image data. Therefore, the image data can be reproduced correctly and an image output result with higher saturation can be obtained.

  In the image file generation device according to the second aspect of the present invention, the conversion destination color space is a color space having at least a part of the same or wider definition area as the color space when generating the image data. Also good. With such a configuration, color space conversion can be executed without impairing the color specification area in which the image data at the time of generation is represented.

  In the image file generation device according to the first or second aspect of the present invention, the image file generation device may be a digital still camera.

  A third aspect of the present invention provides a program for generating an image file. A program according to a third aspect of the present invention generates an image file that stores a function of generating image data, information on a color space used in the image processing apparatus, and the generated image data in association with each other. The function to perform is realized by a computer.

  According to the program according to the third aspect of the present invention, it is possible to obtain the same operation as the image file generating apparatus according to the first aspect of the present invention. Further, the program according to the third aspect of the present invention can be realized in various aspects in the same manner as the image file generation apparatus according to the first aspect of the present invention.

  A fourth aspect of the present invention provides a program for generating an image file. A program according to a fourth aspect of the present invention includes a function for acquiring image data, a function for specifying a conversion destination color space for color space conversion executed in the image processing apparatus, and the specified conversion destination color space. A function of generating an image file that stores information and the generated image data in association with each other is realized by a computer.

  According to the program according to the fourth aspect of the present invention, it is possible to obtain the same operation as the image file generating apparatus according to the second aspect of the present invention. Further, the program according to the fourth aspect of the present invention can be realized in various aspects in the same manner as the image file generation device according to the second aspect of the present invention.

  According to a fifth aspect of the present invention, there is provided an image processing apparatus for executing image processing on an image file including image data and color space information. An image processing apparatus according to a fifth aspect of the present invention includes an image file acquisition unit that acquires an image file, a search unit that searches for the color space information from the acquired image file, and the color space information is searched. In this case, the image processing apparatus includes a color conversion processing unit that converts a color space of the image data based on the color space information.

  According to the image processing apparatus of the fifth aspect of the present invention, since the color conversion processing means for converting the color space of the image data based on the color space information is provided, the color processing information based on the color space information included in the image file is provided. The color space of the image data can be converted. Therefore, the image data can be accurately reproduced.

  In the image processing device according to the fifth aspect of the present invention, when the color space information is not searched, the color conversion processing means converts the color space of the image data based on predetermined color space information. Also good. When such a configuration is provided, the color space of the image data can be converted based on the predetermined color space information even when the image file does not include color space information.

  In the image processing device according to the fifth aspect of the present invention, the image data included in the image file is represented by a first color space, and the image file acquisition means includes the acquired image file. The color space of the included image data is converted from the first color space to the second color space, and the color conversion processing means converts the color space of the image data from the second color space to the third color space. It may be converted to a color space.

  In the image processing device according to the fifth aspect of the present invention, the first color space is a YCbCr color space, the second color space is a first RGB color space, and the third color The space may be a second RGB color space having at least a part thereof equal to or wider than the first RGB color space. By providing such a configuration, color space conversion can be executed without impairing the color reproduction region of the image data in the first RGB color space, and more than when image data in the first RGB color space is used. Image with high saturation can be obtained.

  In the image processing device according to the fifth aspect of the present invention, the second RGB color space may be at least as wide as the color space used when generating the image data. In such a case, the color space conversion process can be executed by utilizing the color reproduction region of the color space at the time of image data generation. The third color space may be a CIELAB color space. In such a case, since image data in the absolute color space is obtained, further image processing can be easily executed.

  The image processing apparatus according to the fifth aspect of the present invention may further include output means for outputting the image data subjected to the image processing. In such a case, image data can be output.

  The sixth aspect of the present invention provides a program for executing image processing on an image file including image data and color space information. The program according to the sixth aspect of the present invention includes a function for acquiring an image file, a function for searching for the color space information from the acquired image file, and the color space information when the color space information is searched. A function for converting the color space of the image data based on the spatial information is realized by a computer.

  According to the program according to the sixth aspect of the present invention, it is possible to obtain the same operational effects as those of the image processing apparatus according to the fifth aspect of the present invention. Further, the program according to the sixth aspect of the present invention can be realized in various aspects in the same manner as the image processing apparatus according to the sixth aspect of the present invention.

  In addition, it cannot be overemphasized that each aspect which concerns on this invention can be implement | achieved in the format of a method and a recording medium besides this.

Hereinafter, an image output apparatus according to the present invention will be described based on several embodiments with reference to the drawings in the following order.
A. Configuration of image data output system including image output apparatus Configuration of image output apparatus Image processing in image output apparatus Other examples

A. Configuration of an image data output system including an image output device:
A configuration of an image data output system to which the image processing apparatus according to the first embodiment can be applied will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing an example of an image data output system to which the image output apparatus according to the first embodiment can be applied. FIG. 2 is a block diagram showing a schematic configuration of a digital still camera capable of generating an image file (image data) output from the image output apparatus according to the first embodiment.

  An image data output system 10 is a digital still camera 12 as an input device that generates an image file, and performs image processing based on an image file generated by the digital still camera 12 and outputs a color as an output device that outputs an image. A printer 20 is provided. As the output device, in addition to the printer 20, a monitor 14 such as a CRT display or LCD display, a projector, or the like can be used. In the following description, the color printer 20 is used as the output device.

  The digital still camera 12 is a camera that acquires an image by imaging light information on a digital device (CCD or photomultiplier tube). As shown in FIG. 2, an optical circuit 121 for collecting optical information, An image acquisition circuit 122 for controlling the digital device to acquire an image, an image processing circuit 123 for processing the acquired digital image, and a control circuit 124 for controlling each circuit are provided. The digital still camera 12 stores the acquired image as digital data in a memory card MC as a storage device. As a storage format of image data in the digital still camera 12, a JPEG format is generally used, but other storage formats such as a TIFF format, a GIF format, a BMP format, and a RAW format can be used. The digital still camera 12 also includes a selection / determination button 126 for selecting and setting various functions.

  Image data generated by the digital still camera 12 is defined in the RGB color space. As the RGB color space used at this time, the sRGB color space is the most general, but an NTSC-RGB color space having a wider color gamut than the sRGB color space may be selected. When the data represented in the RGB color space is stored in a memory card, it is converted into a YCbCr color space having color space characteristics suitable for the JPEG format, which is a format for compressing and storing the data. When saving image data in the JPEG format, the image data represented in the RGB color space is subjected to an operation using an inverse matrix of the matrix S described later, and the color space of the image data is converted to the RGB color space. For example, the sRGB color space is converted to the YCbCr color space. Note that when converting from the sRGB color space to the YCbCr color space, color values outside the sRGB color space, that is, negative data as color values are also converted while being valid.

  The digital still camera 12 used in the image data output system 10 stores the image processing control information GI as an image file in the memory card MC in addition to the image data. The image file generated by the digital still camera 12 usually has a file structure in accordance with the digital still camera image file format standard (Exif) in order to maintain the compatibility of the image file. Exif file specifications are defined by the Japan Electronics and Information Technology Industries Association (JEITA).

  A schematic structure inside the image file when the file format conforms to the Exif file format will be described with reference to FIG. FIG. 3 is an explanatory diagram showing a schematic internal structure of the image file 100 stored in the Exif file format. 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 file 100 as an Exif file includes a JPEG image data storage area 101 for storing image data in JPEG format, and an attached information storage area 102 for storing various attached information related to the stored JPEG image data. In the attached information storage area 112, shooting time information relating to shooting conditions of a JPEG image such as a shooting color space, shooting date / time, exposure, shutter speed, and the like, and thumbnail image data of the JPEG image stored in the JPEG image data storage area 101 are stored. It is stored in TIFF format. The attached information is automatically stored in the attached information storage area 102 when the image data is written to the memory card MC. The attached information storage area 102 includes a Makernote data storage area 103 that is an undefined area released to the DSC manufacturer, and the DSC manufacturer stores arbitrary information in the Makernote data storage area 103. be able to. As is well known to those skilled in the art, tags are used in the Exif format file to identify each piece of data.

  The Makernote data storage area 103 also has a configuration capable of identifying the data stored by the tag. In this embodiment, image processing control information GI for controlling image processing in the color printer 20 is stored. .

  The image processing control information GI is information for designating image output conditions so that an optimum image output result can be obtained in consideration of color reproduction characteristics and image output characteristics of an output device such as the color printer 20. The information stored as the image processing control information GI includes, for example, parameters relating to a gamma value, a target color space, contrast, color balance adjustment, sharpness, and color correction. The parameter relating to the target color space specifies the color space executed during image processing in the output device, more specifically, the matrix value of the color space conversion matrix. The parameter relating to the color space is color space information that can be arbitrarily designated (set) independently of the color space at the time of image data generation.

  The image file GF generated in the digital still camera 12 is sent to the color printer 20 via, for example, the cable CV, the computer PC, or via the cable CV. Alternatively, an image file is sent to the color printer 20 through a computer PC connected to the memory card MC mounted on the digital still camera 12 or by directly connecting the memory card MC to the printer 20. The In the following description, the case where the memory card MC is directly connected to the color printer 20 will be described.

B. Image output device configuration:
The schematic configuration of the image output apparatus according to the first embodiment, that is, the color printer 20, will be described with reference to FIG. FIG. 4 is a block diagram showing a schematic configuration of the color printer 20 according to the first embodiment.

  The color printer 20 is a printer that can output a color image. For example, four color inks of cyan (C), magenta (M), yellow (Y), and black (K) are ejected onto a print medium. An ink jet printer that forms an image by forming a dot pattern, or an electrophotographic printer that forms an image by transferring and fixing color toner onto a printing medium. In addition to the above four colors, light cyan (light cyan, LC), light magenta (light magenta, LM), and dark yellow (dark yellow, DY) may be used as the color ink.

  As shown in the figure, the color printer 20 drives a print head 211 mounted on a carriage 21 to eject ink and form dots, and the carriage 21 is reciprocated in the axial direction of a platen 23 by a carriage motor 22. A mechanism for conveying the printing paper P by the paper feed motor 24, and a control circuit 30. The mechanism for reciprocating the carriage 21 in the axial direction of the platen 23 is an endless drive between the carriage motor 22 and the slide shaft 25 that slidably holds the carriage 21 laid in parallel with the axis of the platen 23. A pulley 27 that stretches the belt 26, a position detection sensor 28 that detects the origin position of the carriage 21, and the like. The mechanism for transporting the printing paper P includes a platen 23, a paper feed motor 24 that rotates the platen 23, a paper feed auxiliary roller (not shown), and a gear train that transmits the rotation of the paper feed motor 24 to the platen 23 and the paper feed auxiliary roller. (Not shown).

  The control circuit 30 appropriately controls the movement of the paper feed motor 24, the carriage motor 22, and the print head 211 while exchanging signals with the operation panel 29 of the printer. The printing paper P supplied to the color printer 20 is set so as to be sandwiched between the platen 23 and the paper feed auxiliary roller, and is fed by a predetermined amount according to the rotation angle of the platen 23.

  An ink cartridge 212 and an ink cartridge 213 are mounted on the carriage 21. The ink cartridge 212 contains black (K) ink, and the ink cartridge 213 contains light cyan (LC) in addition to other inks, that is, three color inks of cyan (C), magenta (M), and yellow (Y). ), Light magenta (LM), and dark yellow (DY).

  Next, the internal configuration of the control circuit 30 of the color printer 20 will be described with reference to FIG. FIG. 5 is an explanatory diagram showing the internal configuration of the control circuit 30 of the color printer 20. As shown in the figure, the control circuit 30 includes a CPU 31, a PROM 32, a RAM 33, a PCMCIA slot 34 for acquiring data from the memory card MC, a peripheral device input / output for exchanging data with the paper feed motor 24, the carriage motor 22, and the like. A unit (PIO) 35, a timer 36, a drive buffer 37, and the like are provided. The drive buffer 37 is used as a buffer for supplying dot on / off signals to the ink ejection heads 214 to 220. These are connected to each other by a bus 38 and can exchange data with each other. The control circuit 30 is also provided with an oscillator 39 that outputs a drive waveform at a predetermined frequency, and a distribution output device 40 that distributes the output from the oscillator 39 to the ink ejection heads 214 to 220 at a predetermined timing.

  The control circuit 30 reads the image file 100 from the memory card MC, analyzes the image processing control information GI, and executes image processing based on the analyzed image processing control information GI. The control circuit 30 outputs dot data to the drive buffer 37 at a predetermined timing while synchronizing with the movements of the paper feed motor 24 and the carriage motor 22. The detailed image processing flow executed by the control circuit 30 will be described below.

C. Image processing in the image output device:
Image processing in the color printer 20 according to the first embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing a processing routine of printing processing in the color printer 20 according to the first embodiment. FIG. 7 is a flowchart showing the flow of image processing in the color printer 20.

  When the memory card MC is inserted into the slot 34, the control circuit 30 (CPU 31) of the printer 20 reads the image file 100 from the memory card MC, and temporarily stores the read image file 100 in the RAM 33 (step S100). The CPU 31 acquires the image processing control information GI from the read image file 100, and searches for a ColorSpace tag that designates a color space during image processing (step S110). If the ColorSpace tag can be retrieved and found (step S120: Yes), the CPU 31 acquires and analyzes the designated color space information (step S130). The CPU 31 executes image processing to be described in detail later based on the analyzed color space information (step S140), and prints out the processed image data (step S150).

  If the CPU 31 cannot find or find the ColorSpace tag (step S120: No), the CPU 31 acquires from the ROM 32 the color space information that the color printer 20 has in advance as a default value, for example, information on the sRGB color space. Normal image processing is executed (step S160). The CPU 31 prints out the processed image data (step S150) and ends this processing routine.

  Image processing executed in the color printer 20 will be described in detail with reference to FIG. The control circuit 30 (CPU 31) of the color printer 20 extracts the image data GD from the read image file 100 (step S200). As described above, the digital still camera 12 stores image data as a file in JPEG format. In the JPEG file, in order to increase the compression rate, the color space (sRGB color space) of the generated image data is set to YCbCr. Image data is saved after conversion to color space.

  However, since personal computers and printers can usually handle only image data expressed in the RGB color space, the color space of the image data expressed in the YCbCr color space is converted to the RGB color space. There is a need to.

  The CPU 31 executes a 3 × 3 matrix operation S in order to convert the YCbCr image data into RGB image data (step S210). The matrix operation S is an arithmetic expression for converting the color space of the image data from the YCbCr color space to the RGB color space defined by the JPEG FIle Interchange Format (JFIF) standard. It is.

  When executing this matrix operation S, the CPU 31 obtains a first positive color value (image data in the RGB color space obtained after the conversion) representing a defined region of a predetermined RGB color space, for example, an sRGB color space ( Even if it has a second positive color value (color value) exceeding the region of the color value) or a negative color value (color value) that takes a negative value in the RGB color space, the second color value (color value) The positive color value and the negative color value are treated as valid values without being clipped, that is, rounded (truncated), in the definition area of the sRGB color space, and stored as they are together with the first positive color value. Accordingly, when the image data has the second positive color value or the negative color value, the data capacity becomes larger than 8 bits. The sRGB color space is used as an example because it is a color space generally used in a standard operating system (OS).

  The CPU 31 executes gamma correction and matrix operation M on the image data in the RGB color space thus obtained (step S220). The process executed here is a process executed according to the color space information specified in the image processing control information GI and the gamma value. When executing gamma correction, the CPU 31 refers to the gamma value in the above-described parameters, and executes gamma conversion processing on the video data using the set gamma value (DSC eigenvalue).

  The matrix operation M is an operation process for converting the RGB color space into the XYZ color space. Each matrix value of the 3 × 3 matrix (M) used for the matrix operation M is a matrix value specified by the image processing control information GI, and is stored at an address specified by the ColorSpace tag. The CPU 31 executes a matrix operation M using the written matrix value. At this time, the matrix value specified by the image processing control information GI is a matrix value that defines a matrix for converting the sRGB color space and the NTSC color space into the XYZ color space. Here, the color space information described in the ColorSpace tag is reflected through the XYZ color space because the XYZ color space is an absolute color space and is a device-independent color space that does not depend on devices such as DSC and printer. It is. When color space is converted, device-independent color matching can be performed by matching color values in each color space in XYZ color space. The matrix operation M is an arithmetic expression shown below.

  The color space areas (color reproduction areas) of the visible area (VA), sRGB (SR), NTSC (NS), and wRGB (WR) on the RGB color space are as shown in FIG. As can be understood from FIG. 8, the sRGB color space has the narrowest color space region, and the NTSC color space region and the wRGB color space region have a color space region wider than the sRGB color space region.

  The color space of the image data GD obtained after execution of the matrix operation M is an XYZ color space. Conventionally, the color space used for image processing in a printer or computer is fixed to sRGB, and the color space of the digital still camera 12 cannot be used effectively. On the other hand, in the present embodiment, a target color space (matrix value) at the time of image processing is specified by the image processing control information GI of the image file GF, and the specified color space (specified matrix value) is designated. A printer (printer driver) that changes the matrix (M) used for the matrix operation M is used. Therefore, in the digital still camera 12, even when image data is generated in the NTSC-RGB color space having a space wider than the sRGB color space, by specifying the NTSC-RGB color space as the target color space, Effective color reproduction can be realized by effectively using the color space in which data is generated.

The CPU 31 executes a process of converting the color space of the image data GD from the XYZ color space to the wRGB color space, that is, matrix calculation N ⁻¹ and inverse gamma correction in order to execute image adjustment based on an arbitrary image quality adjustment parameter. (Step S230). Note that the wRGB color space is wider than the sRGB color space as shown in FIG. 8, and the second positive color value and the negative color value that are not included in the definition area and are not expressed in the sRGB color space are It can be treated as an expressible color value included in the definition region of the wRGB color space. When executing the inverse gamma correction, the CPU 31 refers to the gamma value on the color printer 20 side in the above-described parameters, and performs inverse gamma conversion processing on the image data using the inverse of the set gamma value. Execute. When executing the matrix operation N ⁻¹ , the CPU 31 executes the matrix operation using the matrix (N ⁻¹ ) corresponding to the conversion from the ROM 31 to the wRGB color space. Matrix operation N ⁻¹ is an arithmetic expression shown below.

The color space of the image data GD obtained after executing the matrix operation N ⁻¹ is the wRGB color space. As described above, this wRGB color space is a color space wider than the sRGB color space, and originally includes an RGB color space that can be expressed by the digital still camera 12 in its definition area.

  The CPU 31 executes automatic image adjustment for characterizing the image (step S240). The processing executed here is processing executed according to image quality adjustment information arbitrarily set in the image processing control information GI. When executing automatic image adjustment, the CPU 31 refers to parameter values such as brightness and sharpness from among the parameters described above, and performs image adjustment on the video data using the set parameter values. To do. When the automatic adjustment parameter is designated, other parameter values that are arbitrarily designated are reflected based on the parameter value designated by the automatic adjustment parameter.

  Even when the image quality adjustment information is not specified in the image processing control information GI of the image file GF, the automatic adjustment parameter, for example, the parameter indicating the shooting scene is automatically set on the digital still camera 12 side. Therefore, the CPU 31 performs image adjustment according to the automatic adjustment parameter value.

  The CPU 31 executes wRGB color conversion processing and halftone processing for printing (step S250). In the wRGB color conversion process, the CPU 31 refers to a lookup table (LUT) for conversion to the CMYK color space corresponding to the wRGB color space stored in the ROM 32, and changes the color space of the image data from the wRGB color space to the CMYK. Change to color space. That is, image data composed of R, G, and B gradation values is converted into gradation value data of, for example, C, M, Y, K, LC, and LM, which are used by the printer 24.

  In the halftone process, the color-converted image data is received and the gradation number conversion process is performed. In this embodiment, the image data after color conversion is expressed as data having a 256 gradation width for each color. On the other hand, in the color printer 20 of the present embodiment, only the state of “forming dots” or “not forming dots” can be taken. That is, the printer 24 of this embodiment can only express two gradations locally. Therefore, the image data having 256 gradations is converted into image data expressed in 2 gradations that can be expressed by the color printer 20. As a representative method of the two gradation processing (binarization), there are a method called an error diffusion method and a method called a systematic dither method.

  In the color printer 20, prior to color conversion processing, when the resolution of image data is lower than the printing resolution, new data is generated between adjacent image data by performing linear interpolation, and conversely higher than the printing resolution. Performs a resolution conversion process for converting the resolution of the image data into the print resolution by thinning out the data at a constant rate. In addition, the color printer 20 executes an interlace process in which the image data converted into a format representing the presence / absence of dot formation is rearranged in the order to be transferred to the color printer 20.

  In this embodiment, all image processing is executed in the color printer 20, and a dot pattern is formed on the print medium according to the generated image data. However, all or part of the image processing is executed on the computer PC. You may make it do. In this case, the image data processing application installed in the hard disk or the like of the computer PC is realized by providing the image processing function described with reference to FIG. The image file GF generated by the digital still camera 12 is provided to the computer PC via the cable CV or via the memory card MC. On the computer PC, an application is started by a user operation, and the image file GF is read, the image processing control information GI is analyzed, and the image data GD is converted and adjusted. Alternatively, the application is automatically started by detecting the insertion of the memory card MC or by detecting the insertion of the cable CV, reading the image file GF, analyzing the image processing control information GI, The conversion and adjustment of the image data GD may be automatically performed.

  As described above, according to the digital still camera 12 according to the first embodiment, it is possible to generate an image file that can specify color space information to be used in the color conversion process executed by the printer 20. it can. Therefore, the color space characteristics used by the digital still camera can be correctly interpreted by the printer 20. Further, according to the image processing in the color printer 20 according to the first embodiment, a target color space at the time of image processing, for example, a matrix value of a color conversion matrix is set based on the image processing control information GI included in the image file GF. Since the color conversion process of the image data GD is executed, the color of the image data can be correctly reproduced. Therefore, it is possible to prevent the difference between the photographing result in the digital still camera 12 and the output result in the color printer 20 caused by the difference in the color space. Furthermore, the color reproduction characteristics of the digital still camera 12 can be correctly reproduced.

  The color printer 20 also includes a CMYK color space conversion table corresponding to a wRGB color space wider than the sRGB color space. Therefore, the image data generated by the digital still camera 12 and distributed outside the definition area of the sRGB color space can be effectively handled, and the image data distributed outside the definition area of the sRGB color space can be used. High saturation printing results can be obtained. That is, a print result with higher saturation can be obtained using color information that cannot be expressed because it exists outside the definition area in the sRGB color space.

D. Other examples:
Image processing in the color printer 20 may be executed as shown in FIG. FIG. 9 is a flowchart showing image processing in the color printer 20 as the second embodiment. In this embodiment, when the color space characteristic is changed from the sRGB color space to the wRGB color space, the matrix operation M and the matrix operation N ⁻¹ are set as one matrix operation (MN ⁻¹ ) (step S320), and high-speed image processing is performed. We are trying to make it.

Further, the image processing in the color printer 20 may be executed as shown in FIG. FIG. 10 is a flowchart showing image processing in the color printer 20 as the third embodiment. In this embodiment, automatic image adjustment is first executed for image data expressed in the YCbCr color space (step 410). Subsequently, a matrix S operation (step S420), a matrix M operation (step S430), and a matrix N- ¹ operation (step S440) are executed on the image data for which automatic image adjustment has been completed, and color space conversion is performed. Run sequentially.

  In each of the image processing embodiments described above, the color printer 20 is used as the output device. However, a display device such as a CRT, LCD, or projector can also be used as the output device. In such a case, for example, an image processing program (display driver) that executes the image processing described with reference to FIG. 7 or the like is executed by the display device as the output device. Alternatively, when a CRT or the like functions as a computer display device, an image processing program is executed on the computer side. However, finally output image data has an RGB color space instead of a CMYK color space.

  In such a case, the display result on the display device such as a CRT is designated by the image file GF in the same manner that the print result via the color printer 20 can reflect the color space of the image data generated by the digital still camera 12. can do. Therefore, by providing the image processing control information GI of the image file GF with parameters suitable for a display device such as a CRT, and by providing parameters optimized for the display characteristics of each display device, the digital still The image data GD generated by the camera 12 can be displayed more accurately.

  In the above-described embodiment, an example in which the image file GF is generated by the digital still camera 20 has been described. However, the image file GF may be an input device (image file generation device) such as a digital video camera (DVC) or a scanner. ). When generated by a digital video camera, for example, an image file storing still image data and output control information, or a moving image file including moving image data such as MPEG format and output control information is generated. The When this moving image file is used, output control according to the output control information is performed on all or some of the frames of the moving image.

  As described above, the image data generation device and the image data output device according to the present invention have been described based on some embodiments. However, the above-described embodiments are for facilitating the understanding of the present invention. The present invention is not limited to this. The present invention can be changed 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.

  For example, in the first embodiment, the specified color can be specified during the matrix M calculation without executing the process of validating (holding) the second positive color value and the negative color value during the matrix S calculation. You may perform the process which reflects spatial information. In such a case, the color space at the time of image data generation can be correctly interpreted during image processing, and correct color reproduction can be realized. Therefore, it is possible to execute device-independent color space conversion processing that is not affected by the color space unique to the device such as the input device or the output device. As a result, an output result similar to the output result of the image data obtained at the time of shooting can be obtained from the output device.

The illustrated parameters are merely examples, and the invention according to the present application is not limited by these parameters. Further, the matrix values of the matrices S, M, and N ⁻¹ in each mathematical expression are merely examples, and it goes without saying that the values can be appropriately changed depending on the target color space or the color space that can be used in the color printer 20. Nor.

  In each of the above embodiments, the digital still camera 12 has been described as the image file generating device. However, a scanner, a digital video camera, or the like can be used. When using a scanner, the basic information and arbitrary information of the image file GF may be designated on the computer PC, or a preset button in which setting information is assigned in advance for setting information on the scanner. A display screen for setting and a setting button may be provided so that the scanner can be executed alone.

  The color spaces used in the above embodiments are merely examples, and other color spaces may be used. In either case, the image data generated by the image data generation device such as the digital still camera 12 may be output reflecting the color space of the image data generation device.

  In the first embodiment, the Exif format file has been described as an example of the image file GF, but the format of the image file according to the present invention is not limited to this. In other words, any image file that includes at least image data to be output by the output device and information on the color space used in the image data generation device such as the digital still camera 12 may be used. This is because such a file can reduce the difference in output image between the image data generated in the image data generation device (image display obtained via a monitor or the like) and the output image in the output device. .

  For the image file GF including the image data and the output device control information CI, association data for associating the output device control information CI is generated, and the image data and the output device control information CI are stored in independent files. In addition, a file that can associate the image data with the output device control information CI with reference to the association data at the time of image processing is also included. In such a case, although the image data and the output device control information CI are stored in separate files, the image data and the output device control information CI are inseparably integrated at the time of image processing using the output device control information CI. This is because they function in the same manner as when they are stored in substantially the same file. That is, an aspect in which the image data and the output device control information CI are used in association with each other at least at the time of image processing is included in the image file GF in the present embodiment. Furthermore, a moving image file stored in an optical disc medium such as a CD-ROM, a CD-R, a DVD-ROM, a DVD-RAM is also included.

  The color printer 20 according to the first embodiment is merely an example, and the configuration is not limited to the description of each embodiment. The color printer 20 only needs to analyze at least the image processing control information GI of the image file GF and output (print) the image according to the described or designated color space information.

It is explanatory drawing which shows an example of the image data output system which can apply the image output apparatus which concerns on 1st Example. It is a block diagram which shows schematic structure of the digital still camera which can produce | generate the image file (image data) which the image output device which concerns on 1st Example outputs. It is explanatory drawing which shows the schematic internal structure of the image file 100 stored in the Exif file format. 1 is a block diagram illustrating a schematic configuration of a color printer 20 according to a first embodiment. 2 is an explanatory diagram illustrating an internal configuration of a control circuit 30 of the color printer 20. FIG. 4 is a flowchart illustrating a processing routine of a printing process in the color printer 20 according to the first embodiment. 3 is a flowchart illustrating a flow of image processing in the color printer 20 according to the first embodiment. It is explanatory drawing which shows the color space area | region of visible region (VA), sRGB (SR), NTSC (NS), and wRGB (WR) on RGB color space. It is a flowchart which shows the image processing in the color printer 20 as a 2nd Example. It is a flowchart which shows the image processing in the color printer 20 as a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image data output system 12 ... Digital still camera 121 ... Optical circuit 122 ... Image acquisition circuit 123 ... Image processing circuit 124 ... Control circuit 126 ... Selection / decision button 14 ... Display 20 ... Color printer 21 ... Carriage 211 ... Print head 212 Ink cartridge 213 ... Ink cartridge 214 to 220 ... Ink ejection head 22 ... Carriage motor 23 ... Platen 24 ... Paper feed motor 25 ... Sliding shaft 26 ... Drive belt 27 ... Pulley 28 ... Position detection sensor 29 ... Operation panel 30 ... Control circuit 31 ... arithmetic processing unit (CPU)
32. Programmable read only memory (PROM)
33 ... Random access memory (RAM)
34 ... PCMCIA slot 35 ... Peripheral device input / output unit (PIO)
36 ... Timer 37 ... Drive buffer 38 ... Bus 39 ... Oscillator 40 ... Distribution output device 100 ... Image file (Exif file)
101 ... JPEG image data storage area 102 ... Attached information storage area 103 ... Makernote storage area MC ... Memory card

Claims (17)

An image file generation device,
Image data generating means for generating image data;
An image file generation apparatus comprising: an image file generation unit configured to generate an image file that stores information on a color space used in an image processing apparatus in association with the generated image data. The image file generation device according to claim 1,
The color space information is an image file generation device that is a matrix value used during color space conversion processing executed in the image processing device. The image file generation device according to claim 1 or 2, further comprising:
Color space information designating means for designating color space information used in the image processing apparatus;
Color space information storage means for storing a plurality of color space information that can be designated as the color space information,
The color space information specifying means includes
Display means for displaying the stored color space information;
An image file generation apparatus comprising: selection means for selecting one color space information from displayed color space information. The image file generation device according to claim 1 or 2, further comprising:
Color space information designating means for designating color space information used in the image processing apparatus;
Color space information storage means for storing a plurality of combinations of identification information for identifying an image processing apparatus that performs image processing on the image file and color space information that can be specified as information on the color space. ,
The color space specifying means includes
Display means for displaying candidate image processing apparatuses for performing image processing;
An image file generation device comprising: selection means for selecting one image processing device from displayed image processing device candidates. An image file generation device,
Image data acquisition means for acquiring image data;
Color space specifying means for specifying a destination color space for color space conversion executed in the image processing apparatus;
An image file generation apparatus comprising: an image file generation unit configured to generate an image file for storing the specified conversion destination color space information and the acquired image data in association with each other. The image file generation device according to claim 5,
The image file generation device, wherein at least a part of the conversion destination color space is a color space having the same or wider definition area as the color space when the image data is generated. The image file generation device according to any one of claims 1 to 6,
The image file generating apparatus is a digital still camera. A program for generating an image file,
A function to generate image data;
A program that causes a computer to realize a function of generating an image file that stores information on color space used in an image processing apparatus in association with the generated image data. A program for generating an image file,
A function to acquire image data;
A function for designating a destination color space for color space conversion executed in the image processing apparatus;
A program that causes a computer to realize a function of generating an image file that stores information on the specified conversion destination color space and the generated image data in association with each other. An image processing apparatus that executes image processing on an image file including image data and color space information,
Image file acquisition means for acquiring an image file;
Search means for searching the color space information from the acquired image file;
An image processing apparatus comprising: color conversion processing means for converting a color space of the image data based on the color space information when the color space information is searched. The image processing apparatus according to claim 10.
When the color space information is not searched, the color conversion processing unit converts the color space of the image data based on predetermined color space information. The image processing apparatus according to claim 10.
The image data included in the image file is represented by a first color space,
The image file acquisition unit converts a color space of image data included in the acquired image file from the first color space to a second color space,
The color conversion processing means converts the color space of the image data from the second color space to a third color space. The image processing apparatus according to claim 12.
The first color space is a YCbCr color space;
The second color space is a first RGB color space;
The third color space is an image processing apparatus in which at least a part of the third color space is a second RGB color space having a color space equivalent to or wider than the first RGB color space. The image processing apparatus according to claim 13.
2. The image processing apparatus according to claim 1, wherein the second RGB color space is at least as wide as the color space used when generating the image data. The image processing apparatus according to claim 13.
The image processing apparatus according to claim 3, wherein the third color space is a CIELAB color space. The image processing apparatus according to any one of claims 10 to 15, further comprising:
An image processing apparatus comprising output means for outputting the image data subjected to the image processing. A program for executing image processing on an image file including image data and color space information,
The ability to retrieve image files,
A function of retrieving the color space information from the acquired image file;
When the color space information is retrieved, a program that causes a computer to realize a function of converting the color space of the image data based on the color space information.

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