METHOD FOR QUANTITATIVE EVALUATION OF LUMINOSITY OF COATED FILM

摘要

PROBLEM TO BE SOLVED: To enhance correlation to a visually evaluated result and quantitatively evaluate a luminosity of a coated film containing a luminous material, by subtracting a specific threshold value from each luminance of a segment divided from an image and summing positive subtracted values. SOLUTION: An artificial sun light 10 (metal halide lamp) is used as a light source and an image is captured by a CCD camera 12. The image transmitted from the camera 12 is divided to a plurality of pixels at an image-analyzing apparatus 14, and a luminance I of each pixel is measured. In other words, the image is split to many segments and the image luminance I of each segment is measured. A threshold valueαwhich is 1.05-1.50 times an average luminance is obtained from a total value of the luminances I of all segments. The threshold value is subtracted from the luminance I of each segment. Positive ones of the subtracted values of all segments are summed to obtain a total luminance S, while negative values are set to 0. A luminosity of a coated film containing a luminous material is quantitatively evaluated based on the total luminance S.