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US 2004/0105581 A1Published application
Method and apparatus for color conversion
AssigneesKabushiki Kaisha Toshiba, Toshiba Tec Kabushiki Kaisha
InventorTakayuki Sawada
Life of this patent
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Abstract
There is disclosed an image processing apparatus of the present invention in which a color region of a range including a color range that can be outputted by an image output device is mapped based on a predetermined mapping function defined between the color region and a color conversion table address space by an address map producing section, so that waste in a color conversion table is inhibited, the number of valid lattice points in the color conversion table increases, and therefore color conversion accuracy is improved.
Claims19
A color conversion method comprising:
- calculating a range of color distribution of inputted image data to obtain a result as a color range parameter;
- producing a mapping function to map a color range including the color distribution range represented by the obtained color range parameter in a first color space and conversing the inputted image data by the mapping function,
- producing a first writing address to write the inputted image data converted by the mapping function into a color conversion table,
- producing a second writing address which is an inverse function of the first writing address;
- reading setting data into the color conversion table from a color conversion master database by using of the second writing address;
- reading a second color space from the color conversion table by using a high-order bit of the first writing address and the setting data;
- and
- converting color referring to second color space data and further interpolating the data to transform color, when the corresponding data does not exist.
5 more elements
A color conversion apparatus comprising:
- an input image color range extracting section which calculates a color distribution range of inputted image data to output the result as a color range parameter;
- an address map producing section which produces a mapping function to map a color range represented by a first color space including the color distribution range represented by the color range parameter in accordance with a predetermined mapping function;
- an address map calculating section which converts the inputted image data in accordance with the mapping function;
- a color conversion table address producing section which produces a write address into a color conversion table;
- an address inverse map calculating section to inversely map/convert the write address into the color conversion table in accordance with an inverse mapping function which is an inverse function of the mapping function produced by the address map producing section;
- a color conversion master database from which setting data is read using an inverse map result of the color conversion table write address supplied from the address inverse map calculating section as a read address;
- a color conversion table in which the setting data read and supplied from the color conversion master database is written beforehand with respect to the color conversion table write address and from which second color space data is read using a high-order bit of an address map calculation result supplied from the address map calculating section as the read address;
- and
- a color conversion section which refers to the second color space data read from the color conversion table and which interpolates the data to output a result.
6 more elements
A color conversion apparatus comprising:
- input image color range extracting means for calculating a color distribution range of inputted image data to output the result as a color range parameter;
- address map producing means for producing a mapping function to subjectively map a color range including the color distribution range represented by the color range parameter in a first color space;
- address map calculating means for converting the inputted image data in accordance with the mapping function;
- color conversion table address producing means for producing a write address into a color conversion table;
- address inverse map calculating means for inversely mapping/converting the write address into the color conversion table in accordance with an inverse mapping function which is an inverse function of the mapping function produced by the address map producing means;
- a color conversion master database from which data is read using an inverse map result of the color conversion table write address supplied from the address inverse map calculating means as a read address;
- a color conversion table in which the data read and supplied from the color conversion master database is written beforehand with respect to the color conversion table write address and from which second color space data is read using a high-order bit of an address map calculation result supplied from the address map calculating means as the read address;
- and
- color conversion means for referring to the second color space data read from the color conversion table and interpolating the data to output a result.
6 more elements
A color conversion method comprising:
- converting inputted lattice point RGB data into intermediate data in a predetermined color space based on an ICC profile of RGB;
- converting the intermediate data into second intermediate data based on the ICC profile of CMYK;
- correcting/processing the second intermediate data to prepare a color conversion table;
- and
- referring to color space data read from the prepared color conversion table to directly color-transform the RGB data which is a color conversion object into CMYK data.
2 more elements
A color conversion apparatus comprising:
- a first color conversion section which converts inputted lattice point RGB data into intermediate data in a predetermined color space based on an ICC profile;
- a second color conversion section which converts the intermediate data converted by the first color conversion section into second intermediate data based on the ICC profile;
- a correcting/processing section which corrects the second intermediate data produced by the second color conversion section;
- a color conversion table in which a corrected value corrected by the correcting/processing section is held;
- and
- a direct color conversion section which refers to color space data read from the color conversion table to convert RGB data which is a color conversion object into CMYK data.
3 more elements
Dependencies are inferred from the claim text.