Color gradation correction system of combination of looking-up table and interpolation and method thereof

A method of correcting three kinds of color gradation input data, each having an m bit length, to produce three corresponding kinds of corrected color gradation data each having an m bit length, comprising the steps of:

• calculating corrected color gradation data having an m bit length;
• storing the most significant n bits of the calculated corrected color gradation data in a first memory means in three-dimensional coordinates, where m is greater than n;
• storing the least significant (m-n) bits of the corrected color gradation data as coordinate correction data in a second memory means, the coordinate correction data being for determining spatial location of said three-dimensional coordinates and for determining a number of times said spatial location is to be selected;
• obtaining coordinate correction data from the second memory means for each of the three kinds of color gradation input data on the basis of the least significant (m-n) bits of color gradation input data in response to first to third operation timings;
• adding the respective most significant n bits of each of the three types of color gradation input data to corresponding coordinate correction data;
• outputting calculated color gradation corrected data from three-dimensional coordinates defined by the corrected coordinates;
• and calculating averages of the output color gradation corrected data.

A method for correcting color gradation data having an m bit length for each of three colors, comprising the steps of:

• calculating 2.sup.n corrected color gradation data words each having an m bit length for each of the three colors, wherein n<m;
• storing the corrected color gradation data words in a first memory means so that the data words are arranged in a three-dimensional coordinate space;
• determining coordinate correction data from the least significant m-n bits of color gradation data input data words each having an m bit length for each of the three colors, the coordinate correction data for determining a spatial location of the corrected color gradation data words in the three-dimensional coordinate space in the first memory means and for determining a number of times that the spatial location is to be selected;
• reading out the stored corrected color gradation data words 2.sup.m-n times, wherein each stored corrected color gradation data word is selected as a function of the most significant n bits of each color gradation data input word and the coordinate correction data associated therewith, and wherein the number of times each stored corrected color gradation word is selected is a function of the coordinate correction data;
• and averaging the read-out stored corrected color gradation data words to produce respective corrected color gradation output data words each having an m bit length for each of the three colors.

A system for correcting color gradation data having an m bit length for each of three colors, comprising:

• means for storing previously determined 2.sup.n corrected color gradation data words each having an m bit length for each of three colors, wherein n<m, the corrected color gradation data words being arranged in a three-dimensional coordinate space;
• means for determining coordinate correction data from the least significant m-n bits of color gradation data input words each having an m bit length for each of three colors, the coordinate correction data being for determining a spatial location of the corrected color gradation data words in said three-dimensional coordinate space and for determining a number of times that the spatial location is to be selected;
• means for reading out the stored corrected color gradation data words 2.sup.m-n times, wherein each stored corrected color gradation data word is selected as a function of the most significant n bits of each color gradation data input word and the coordinate correction data associated therewith, and wherein the number of times each stored corrected color gradation word is selected is a function of the coordinate correction data;
• and means for averaging the read-out stored corrected color gradation data words to produce a respective corrected color gradation output data word of m bits for each of the three colors.