A New Objective Sharpness Evaluation Method for Digital Halftone Images

摘要

A new objective sharpness evaluation method independent of tone reproduction methods has been developed using a cooperative human vision model which can simulate various kinds of perceptual responses. In order to clarify the performance of the proposed method, it was applied to sharpness evaluation for three kinds of images: generalized continuous-tone knife-edge images composed of a pair of white and black lines with variable line-widths and their digital halftone images based on an error-diffusion method and an ordered dither method. Consequently, the correlation coefficients between the objective and subjective evaluation values were over 0.97. These results suggest that the proposed method is effective in reproducing human subjective judgments on sharpness irrespective of tone reproduction methods and line-width conditions.