Modulation Transfer Function Model of Assimilation Phenomenon on Monochrome Images Based on Visual Characteristics

Abstract

This paper describes an assimilation phenomenon on monochrome images divided from the size of patterns, and proposes an analytical model about this phenomenon. The frequency spectrum of a sample pattern by the discrete Fourier Transform and human visual characteristics by the Butterworth type Low Pass Filter (LPF) are formulized. A model of the relation between the samples and human visual characteristics, which is additionally introduced the concept of a noise level is proposed, and discussed with the assimilation phenomenon qualitatively and quantitatively. Then, a comparative examination of this model is carried out by subjective evaluation, using the visual distance, and the validity is verified. As a result, the analysis using this proposal model, the cut-off frequency of this LPF is set to 20 cycles/degree, and the noise level presumes -45 dB. The results almost conformed qualitatively to the results of evaluation experiments in this example.