Two-dimensional modulation transfer function model of assimilation phenomenon

This paper describes an assimilation phenomenon on sample images 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 are formulized. A two-dimensional 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 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. Finally, it was shown that the proposed model works with samples having a rotated checked pattern, having various apertures, and having differences in brightness in the constituent colors.