| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a gradation scale curve for efficiently identifying the object of a problem such as a tumor by all concentrations. SOLUTION: The relation of lightness verse logarithm exposure is selected, and a luminance verse lightness curve substantially based on B=L<n> /(L<n> +LO<n> ) is prepared. Also, B is sensed lightness, (n) is preferably within a range 0.7, 0.5<n<1.0, and LO=12.6×(0.2×Lω )<0.63> +1.083×10<-5> ; L is luminance expressed by cd/m<2> , and Lω is the luminance of the minimum concentration area of an X ray film. Concentration verse luminance is used, and a gradation scale curve being the function of logarithm exposure in which the concentration forms an equal lightness difference in a picture in which the equal exposure difference of an objective X ray picture is substantially displayed is formed, and the equal logarithm exposure difference in the objective X ray picture constituted of each stage substantially forms the equal lightness difference in the displayed picture. |
