Patent ID: 6215561
Filing Date: 2001-04-10
Classification: H04N

Abstract:
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 given in a format corresponding to a density of each color component of said color image data;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 configured to store 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;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 and for dividing said predetermined low-density range of said color space, in order to make intervals of the tones of each color component of said color image data stored in said color correction table narrower in said predetermined low-density range than in the other density ranges;color correction means for 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; andtone 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 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 lattice point conversion means is greater than the number of tones obtained by said conversion carried out by said tone number conversion means.