Method and system for the metrological detection of differences in the visually perceived color impression between a multicolored patterned surface of a reference and a multicolored patterned surface of a specimen

A method of metrologically detecting differences in a visually perceived color impression between a multi-color patterned surface of a reference surface and a multi-color patterned surface of an item under test, comprising the stops of:

• detecting a surface of the item under test and obtaining captured signals from the detected surface;
• obtaining a description of color characteristics of the multi-color patterned surface from the captured signals;
• concomitantly obtaining from the captured signals a description of picture definition of the multi-color patterned surface;
• obtaining a color characteristics variation rate by comparing the description of color characteristics with stored corresponding values of the reference surface;
• obtaining a picture definition variation rate by comparing the description of picture definition with corresponding stored values of the reference surface;
• and
• evaluating the visually perceived differences in color impression from the color characteristics variation-rate and the picture definition variation rate.

An arrangement for the metrological detection of differences in a visually perceived color impression between a multi-color patterned reference surface and a multi-color patterned surface of an item under test, comprising:

• a light source with an essentially constant intensity and spectral distribution for illuminating the multi-color patterned surface of the item under test;
• a spatial sensor for detecting the illuminated surface of the item under test;
• an arithmetic unit in which metrological values are determined from captured signals provided by the spatial sensor to describe color characteristics of the multi-color patterned surface of the item under test;
• means for deriving from the captured signals a description of picture definition of the multi-color patterned surface of the item under test;
• and
• display means for displaying a color characteristics variation rate obtained by comparison of the item under test with corresponding stored values of the reference surface, and a picture definition variation rate obtained by comparison of the item under test with corresponding stored values of the reference surface.