Image processing apparatus and image processing method

An image processing apparatus for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said image processing apparatus comprising:

• input means for inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• lattice point information storage means for dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, in such a manner that a predetermined low-density range of said color space is divided into smaller areas than the other density ranges, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• lattice point conversion means for converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said lattice point information storage means according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• color correction data reading means for reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• color correction means for selecting a first value corresponding to a main color among said correction data of said specific lattice point read by said color correction data reading means, reading a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, carrying out interpolation with said first value and said second value, and outputting correction data including the coordinate value with respect to said main color replaced by a result of said interpolation as resulting corrected color image data.

An image processing apparatus for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image wherein each coordinate value of said color image data is defined as a value corresponding to a density of each color component of said color image data, said image processing apparatus comprising:

• input means for inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• lattice point information storage means for dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• lattice point conversion means for converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said lattice point information storage means according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value, said lattice point conversion means having first tone number conversion means for carrying out said conversion of the coordinate values as tone number conversion;
• color correction data reading means for reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• smoothing means for smoothing said correction data of each pixel read by said color correction data reading means, based on correction data of a peripheral pixel in the vicinity of said each pixel;
• and
• second tone number conversion means for converting a number of tones of each color component of said corrected color image data output from said color correction means to a number of tones suitable for an image output unit,
• wherein a number of tones obtained by said conversion of the coordinate values carried out by said first tone number conversion means is greater than the number of tones obtained by said conversion carried out by said second tone number conversion means.

An image processing apparatus for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said image processing apparatus comprising:

• input means for inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• lattice point information storage means for dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• lattice point conversion means for converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said lattice point information storage means according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• color correction data reading means for reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• color correction means for selecting a first value corresponding to a main color among said correction data of said specific lattice point read by said color correction data reading means, reading a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, carrying out interpolation with said first value and said second value, and outputting correction data including the coordinate value with respect to said main color replaced by a result of said interpolation.

An image processing method for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said image processing method comprising the steps of:

• (a) inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones given in a format corresponding to a density of each color component of said color image data;
• (b) dividing said color space by a number of tones less than said predetermined number of tones expressing the coordinate values of said color image data, in such a manner that a predetermined low-density range of said color space is divided in order to make intervals of the tones of each color component of said color image data stored in said color correction table narrower the other density ranges, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• (c) providing a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point and regarding tones of each color component of said color image data;
• (d) converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said step (b) according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• (e) reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table and outputting said correction data read from said color correction table as corrected color image data;
• and
• (f) converting a number of tones of each color component of said corrected color image data output in step (e) to a final number of tones suitable for an image output unit,
• wherein a number of tones obtained by said conversion of the coordinate values carried out by said step (d) is greater than the number of tones obtained by said conversion carried out by said tone number conversion in step (f).

An image processing method for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said image processing method comprising the steps of:

• (a) inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• (b) dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, in such a manner that a predetermined low-density range of said color space is divided into smaller areas than the other density ranges, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• (c) providing a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• (d) converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said step (b) according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• (e) reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• (f) selecting a first value corresponding to a main color among said correction data of said specific lattice point read in said step (e), reading a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, carrying out interpolation with said first value and said second value, and outputting correction data including the coordinate value with respect to said main color replaced by a result of said interpolation as resulting corrected color image data.

An image processing method for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image wherein each coordinate value of said color image data is defined as a value corresponding to a density of each color component of said color image data, said image processing method comprising the steps of:

• (a) inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• (b) dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• (c) providing a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• (d) converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said step (b) according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value, said conversion of the coordinate values carried out as a first tone number conversion;
• (e) reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• (f) smoothing correction data of each pixel read in said step (e), based on correction data of a peripheral pixel in the vicinity of said each pixel;
• and
• (g) carrying out a second conversion of a number of tones of each color component of said corrected color image data read in step (e) to a number of tones suitable for an image output unit,
• wherein a number of tones obtained by said first conversion of the coordinate values carried out in step (d) is greater than the number of tones obtained by said conversion carried out by said second tone number conversion in step (g).

An image processing method for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said image processing method comprising the steps of:

• (a) inputting color image data with respect to each pixel included in said original image, coordinate values of said color image data being expressed by a predetermined number of tones;
• (b) dividing said color space by a number of tones, which is less than said predetermined number of tones expressing the coordinate values of said color image data, and storing coordinate values of lattice points in said color space obtained by carrying out said division for each dimension;
• (c) providing a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point;
• (d) converting the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored in said step (b) according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• (e) reading correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• (f) selecting a first value corresponding to a main color among said correction data of said specific lattice point read in said step (e), reading a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, carrying out interpolation with said first value and said second value, and outputting correction data including the coordinate value with respect to said main color replaced by a result of said interpolation;
• and
• (g) smoothing said correction data of each pixel output in said step (f), based on correction data of a peripheral pixel in the vicinity of said each pixel, and outputting said smoothed correction data as resulting color image data.

A computer program product for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said computer program product comprising:

• a computer readable medium;
• and
• computer program code means stored on said computer readable medium, information previously stored on said computer readable medium comprising:
• coordinate value data representing coordinate values of lattice points in said color space obtained by dividing said color space by a number of tones less than a predetermined number of tones for expressing coordinate values of color image data, for each dimension, in such a manner that a predetermined low-density range of said color space is divided in order to make intervals of the tones of each color component of said color image data stored in said color correction table narrower than the other density ranges;
• and
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point and regarding tones of each color component of said color image data,
• said computer program code means comprising:
• first program code means for causing a computer to input said color image data with respect to each pixel included in said original image, the coordinate values of said color image data being expressed by said predetermined number of tones given in a format corresponding to a density of each color component of said color image data;
• second program code means for causing the computer to convert the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored as said coordinate value data according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• third program code means for causing the computer to read correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table end outputting said correction data reed from said color correction table as corrected color image data;
• and
• fourth program code means for causing the computer to convert a number of tones of each color component of said corrected color image data output from sad third program code means to a final number of tones suitable for an image output unit,
• wherein a number of tones obtained by said conversion of the coordinate values carried out by said second program code means is greater than the number of tones obtained by said conversion carried out by said fourth program code means.

A computer program product for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said computer program product comprising:

• a computer readable medium;
• and
• computer program code means stored on said computer readable medium, information previously stored on said computer readable medium comprising:
• coordinate value data representing coordinate values of lattice points in said color space obtained by dividing said color space by a number of tones, which is less than a predetermined number of tones for expressing coordinate values of color image data, for each dimension, in such a manner that a predetermined low-density range of said color space is divided into smaller areas than the other density ranges;
• and
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point,
• said compute program code means comprising:
• first program code means for causing a computer to input said color image data with respect to each pixel included in said original image, the coordinate values of said color image data being expressed by said predetermined number of tones;
• second program code means for causing the computer to convert the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored as said coordinate value data according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• third program code means for causing the computer to read correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• fourth program code means for causing the computer to select a first value corresponding to a main color among said correction data of said specific lattice point read from said color correction table, to read a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, to carry out interpolation with said first value and said second value, and to output correction data including the coordinate value with respect to said main color replaced by a result of said interpolation as resulting corrected color image data.

A computer program product for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image wherein each coordinate value of said color image data is defined as a value corresponding to a density of each color component of said color image data, said computer program product comprising:

• a computer readable medium;
• and
• computer program code means stored on said computer readable medium, information previously stored on said computer readable medium comprising:
• coordinate value data representing coordinate values of lattice points in said color space obtained by dividing said color space by a number of tones, which is less than a predetermined number of tones for expressing coordinate values of color image data, for each dimension;
• and
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point,
• said compute program code means comprising:
• first program code means for causing a computer to input said color image data with respect to each pixel included in said original image, the coordinate values of said color image data being expressed by said predetermined number of tones;
• second program code means for causing the computer to perform a first conversion in which the coordinate values of said input color image data in said color space are converted to coordinate values of a specific lattice point stored as said coordinate value data according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• third program code means for causing the computer to read correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• and
• fourth program code means for causing the computer to smooth correction data of each pixel read from said color correction table, based on correction data of a peripheral pixel in the vicinity of said each pixel
• fifth program code means for causing the computer to perform a second conversion of a number of tones of each color component of said corrected color image data read by said third program code means to a number of tones suitable for an image output unit,
• wherein a number of tones obtained by said first conversion performed by said second program code means is greater than the number of tones obtained by said second conversion performed by said second tone number conversion in said fifth program code means.

A computer program product for causing a multi-color original image expressed by coordinate values in a multi-dimensional color space to be subjected to color correction and outputting a color-adjusted resulting image, said computer program product comprising:

• a computer readable medium;
• and
• computer program code means stored on said computer readable medium, information previously stored on said computer readable medium comprising:
• coordinate value data representing coordinate values of lattice points in said color space obtained by dividing said color space by a number of tones, which is less than a predetermined number of tones for expressing coordinate values of color image data, for each dimension;
• and
• a color correction table for storing correction data regarding color of said color image data corresponding to each said lattice point,
• said compute program code means comprising:
• first program code means for causing a computer to input said color image data with respect to each pixel included in said original image, the coordinate values of said color image data being expressed by said predetermined number of tones;
• second program code means for causing the computer to convert the coordinate values of said input color image data in said color space to coordinate values of a specific lattice point stored as said coordinate value data according to a technique that makes mean offset of the coordinate values of said input color image data from the coordinate values of said specific lattice point not greater than a predetermined value;
• third program code means for causing the computer to read correction data of said specific lattice point corresponding to the converted coordinate values from said color correction table;
• fourth program code means for causing the computer to select a first value corresponding to a main color among said correction data of said specific lattice point read from said color correction table, to read a second value corresponding to said main color among correction data of an adjoining lattice point that has a coordinate value with respect to said main color different from that of said specific lattice point, to carry out interpolation with said first value and said second value, and to output correction data including the coordinate value with respect to said main color replaced by a result of said interpolation;
• and
• fifth program code means for causing the computer to smooth said output correction data of each pixel, based on correction data of a peripheral pixel in the vicinity of said each pixel, and outputting said smoothed correction data as resulting color image data.