水中物体の写真によるコントラストの推定

抄録

This paper proposes a method for estimating an in-water image contrast using its black-and-white photograph. Contrast values Ci of 26 test boards, each of which has specific coloring composition against black background, were estimated from the proportion of their luminance values under different intensities of illumination ranging from 1500lx to 0.03lx. In other method, each of the test boards was photographed using black-and-white film with different sensitivities based upon the light conditions. Using the particular computer software and scanner, the specific gray values of both target and background for each image photograph were obtained to estimate the comparative contrast value Cg. Results show that increasing light intensities did not enhance the contrast value. In comparison with the contrast estimated from the two methods a relative equation between the Cl and the Cg is presented as : Cl= 0.174 ln Cg十0. 921. Application of this equation to data for the in-water photograph was also discussed.