Are Spatial Chromatic Contrast Sensitivity Band-pass or Lowpass Functions?

TLDR: The results revealed that the chromatic CSF under the present experimental conditions having many lower spatial frequencies covering five colour centres to be band pass, whereas previous results indicated it was low pass, however, this could be caused by the present Experimental conditions such as fixed-size stimuli and constant luminance.

Abstract: The goal of this research is to generate high quality chromatic Contrast Sensitivity Function (CSF) over a wide range of spatial frequencies from 0.06 to 3.84 cycles per degree (cpd) surrounding 5 CIE proposed colour centres (white, red, yellow, green and blue) to study colour difference. At each centre, 6 colour directions at each of 7 frequencies were sampled, from 0.06 to 3.84 cycles per degree (cpd) corresponding to the number of cycles: from 2.3 to 144.4 respectively. A threshold method based on forced-choice stair-case was adopted to investigate the just noticeable (threshold) colour difference. The results revealed that the chromatic CSF under the present experimental conditions having many lower spatial frequencies covering five colour centres to be band pass, whereas previous results indicated it was low pass. However, this could be caused by the present experimental conditions such as fixed-size stimuli and constant luminance. The new chromatic CSF for R-G and Y-B channels were also developed. Introduction The human visual system has different sensitivity to contrast patterns at different spatial frequencies. The function to describe this dependence for simple sinusoidal patterns is called contrast sensitivity function (CSF). The CSF for luminance patterns has been studied extensively and robust models are established. Barten [1] developed two models: one that is a physiologically inspired complex model and the other that is relatively simple and empirically fitted to psychophysical data as given in equation (1). csf(f) = afe!"#)1 + ce"#, $.& , (1)