BS EN 13523-22-2003 specifies a procedure for the determination of Color differences in organic coatings on metal substrates by visually comparing them with the standard in a standard booth with diffuse natural or artificial sunlight. There is a phenomenon of homochromaticity due to the possible difference in results under natural and artificial sunlight. This procedure cannot give a statement of accuracy or accuracy, and is suitable for use when Color measuring instruments are not suitable, such as Color Matching Evaluation, Metal Color Inspection, etc., which are of great significance for key Color Matching and Color Checking.