Color quality assessment and color control during color reproduction

Abstract

A process for color quality assessment and color control in a color printing process is provided. The process utilizes a test element array including several test elements is co-reproduced with an image to be reproduced, whereby for the pixels of the image and the test elements of the test element array, color co-ordinate data are present in an original color space and for the test elements of the test element array the color values are present in an assessment color space are present. The co-reproduced test element array is colorimetrically measured with respect to the assessment color space, color difference of the test elements relative to the corresponding set color values are determined from the measured color values of the color elements and a color quality measure is calculated for the reproduced image and/or color correction quantities are calculated for the color reproduction process. The original color space (AFR) is divided into a larger number of color space areas. A sensitivity matrix is determined for each color space area, which for the underlying color reproduction process in the region of the respective color space area describes the connection between incremental changes of the color correction adjustments of the color reproduction process and thereby in the color reproduction effected color changes with respect to the assessment color space. The color correction quantities required for the color correction are calculated by way of the sensitivity matrixes of the color space areas from the determined color differences of the color elements and the color space weights of the color elements with the condition that the absolute value of the sum of the after execution of the color correction remaining color differences of all color elements of the test element array weighted with the color space weights becomes minimal. The color correction defined by the color correction quantities determined in this manner is then carried out in the color reproduction process.