Patent ID: 7414755

Claim:
A process for color quality assessment in a color reproduction process in which 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 in an original color space and for the test elements of the test element array said color values in an assessment color space are present, and in which the co-reproduced test element array is colorimetrically measured with respect to the assessment color space, color differences of the test elements relative to the corresponding set color values are determined from their measured color values and a color quality measure is calculated for the reproduced image from the color differences of the test elements, whereby (i) the originating color space (AFR) is divided into a larger number of color space areas (FRB i ) each of which is defined by the color co-ordinate values of its center, (ii) a test element array (FT) with a number of color elements (FE i ) corresponding to the number of color space areas (FRB i ) is used, whereby the color co-ordinate values of the color elements correspond to the color co-ordinate values of the centers of the color space areas, (iii) at least for a selected part of the pixels of the image (B) that color space area (FRB i ) per pixel (P) is determined as matching the center of which in the originating color space (AFR) has the smallest distance from the respective pixel (P), (iv) for the selected part of the pixel of the image a weighing portion (G pi ) is determined per pixel (P) for the selected part of the pixels of the image and assigned to the respectively associated color space area (FRB i ), (v) for each color space area (FRB i ) the thereto assigned weighing portions (G pi ) of the pixels (P) are summed up to a color space weight (G i ), (vi) the color differences (dL* i , da* i , db* i ) of the color elements (FE i ) determined on the test element array with respect to the assessment color space (BFR) relative to the set color values are weighed respectively with the color space weight (G i ) of that color space area (FRB) the center color co-ordinate values of which correspond to the color co-ordinate values of the respective color element (FE i ), and (vii) as color quality measure (Q L , Q a , Q b ) the sum of the so weighted color differences (dL iw , da iw , db iw ) is calculated for the reproduced image over all color elements (FE i ) of the test element array (FT).