Suprathreshold contrast perception at different luminance levels

Abstract

Magnitude estimation experiments show that the perceived contrast of sine waves is a linear function of stimulus contrast at some mean luminance ( L m ), spatial frequency and contrast levels, but not at others. For monocular vision at both low and high contrast levels, linearity is observed within a limited zone which, at high L m levels, does not include intermediate frequencies. Binocular vision gives similar results at high contrast levels, while for low levels, the linearity zone comprises intermediate frequencies in a wide L m range. It is demonstrated that if a threshold correction is introduced into the obtained psychophysical functions, the described linearity zones extend to wider L m and contrast ranges.