Method and apparatus for color reproduction

A color reproduction method of converting first color signal data of at least a first color included in a first coloring system forming an original image that has been displayed on a monitor screen into second color signal data of at least a second color included in a second coloring system, by using a first color conversion table, the second color signal data being used for printing the original image as a printed image by a printer, the method comprising the steps of:

• entering a color modification parameter corresponding to a difference between the second color of the second coloring system for the printed image and the first color of the first coloring system for the original image;
• reverse-converting the color modification parameter;
• optimizing an amount to be modified on the first color conversion table based on the reverse-converted the color modification parameter;
• optimizing the same color modification parameter but not reverse-converted;
• calculating a first area to be modified and first data of an amount to be modified on the original image based on the reverse-converted color modification parameter and the original image;
• forming a second color conversion table based on the first area to be modified and the first data of the amount to be modified;
• calculating a second area to be modified and second data of an amount to be modified on the original image based on the color modification parameter that has been optimized but not reverse-converted and the original image;
• calculating first modified image data based on the first color signal data by using the second area to be modified and the second data of the amount to be modified and an image to be modified;
• converting the original image into the second color signal data by using the second color conversion table to generate second modified image data;
• and
• combining the first and second modified image data to generate the image to be modified.

A method of converting first color signal data under 2.sup.n+m gradations into second color signal data, the first color signal data corresponding to at least a first color included in a first coloring system, the second color signal data corresponding to at least a second color included in a second coloring system, the method comprising the steps of:

• entering color mode data indicating the first coloring system and first and second look-up table data;
• judging whether the color mode data is in RGB mode or not;
• inverting the first look-up table data to form a first look-up table if the color mode data is judged as in the RGB mode;
• rearranging the second look-up table data in reverse order to form a second look-up table if the color mode data is judged as in the RGB mode;
• processing the first color signal data using the first look-up table;
• converting the upper n bits of the processed first color signal data into main data of the second color signal data on the basis of the second look-up table;
• outputting interpolation coefficients related to the second look-up table;
• calculating interpolation data for interpolating the main data using the coefficients and the lower m bits of the first color signal data;
• and
• adding the main data and the interpolation data to output the second color signal data.

A method of converting first color signal data in RGB mode under 2.sup.n+m gradations into second color signal data, the first color signal data corresponding to at least a first color included in a first coloring system, the second color signal data corresponding to at least a second color included in a second coloring system, the method comprising the steps of:

• entering color table data composed of pre-inverted first look-up table data and second look-up table data pre-rearranged in reverse order;
• separating the color table data into the first look-up table data and the second look-up table data;
• processing the first color signal data using the first look-up table;
• converting the upper n bits of the processed first color signal data into main data of the second color signal data on the basis of the second look-up table;
• outputting interpolation coefficients related to the second look-up table;
• calculating interpolation data for interpolating the main data using the coefficients and the lower m bits of the first color signal data;
• and
• adding the main data and the interpolation data to output the second color signal data.

An apparatus for color signal adjustment with supplying table data to a printer that modifies a first color signal corresponding to at least a color included in a first coloring system using first input look-up table data, converts the modified first color signal into a second color signal corresponding to at least a color included in a second coloring system using at least first color conversion look-up table data, and adjusts the second color signal so as to be printed as first image using first output look-up table data with the entered table data for printing, the apparatus comprising;

• a memory to store second input look-up table data, second color conversion look-up table data and second output look-up table data identical to the first input look-up table data, the first color conversion look-up table data and the first output look-up table data, respectively;
• a calculator to calculate color data on at least an area of a second image displayed on a monitor;
• a simulator to simulate the calculated color data on the basis of the second input look-up table data and the second color conversion look-up table data stored in the memory;
• and
• a generator to generate a first displaying signal indicating the simulated color data, the first displaying signal being displayed on the monitor as at least a graph indicating input and output characteristics related to the second output look-up table, thus adjusting the first image so as to match the second image.

A color reproduction method of converting first color signal data of at least a first color included in a first coloring system forming an original first image that has been displayed on a monitor screen into second color signal data of at least a second color included in a second coloring system, by using a first color conversion table, the second color signal data being used for printing the original image as a printed image by a printer, the method comprising the steps of:

• display a second image for modification on the monitor screen;
• deciding a color modification parameter corresponding to a difference between the printed image and a third image to be printed at a desired quality by modifying the second image at a degree corresponding to the difference so that the second image is the same as the printed image in image quality;
• and
• reverse-converting the decided color modification parameter for converting the first color signal data into the second color signal data by color conversion, the second color data being printed as a fourth image that is the same as the third image in image quality.