For the problem of low brightness and contrast in weld radiographic images
an image enhancing strategy for human visual system is proposed. The proposed method calibrates the imaging system under the certain conditions
and finds the imaging characteristics of the original image from the calibrating results. Then the objective characteristics are obtained by the imaging poles. The gray-level mapping transformation function is gained and applied to image enhancement. The experimental results demonstrate that the proposed strategy promotes the gray level difference from 145 to 157 and the average gray from 35 to 120 without information loss. Compared with histogram equalization
the proposed strategy enables to improve the average gray of radiographic image to 120 which belongs to the high-resolution gray range of human visual system.