Daylight, biochrome surfaces, and human chromatic response in the Fourier domain

We first report Fourier analyses of a collection of 348 daylight spectral p ower distributions and 1695 biochrome surface reflectance functions. The po wer spectra of the daylights are low pass with more than 99% of spectral po wer below 1 cycle/300 nm and 99.9% below 3 cycles/300 nm. The power spectra of reflectance functions are also low pass with more than 99% of spectral power below 4 cycles/300 nm and 99.9% below 11 cycles/300 nm. Consequently, the resulting color signals are typically low pass with, for our samples, an estimated frequency cutoff of 5 cycles/300 nm. Theoretical and experimen tal data concerning human chromatic response in the frequency domain show t hat this limit corresponds to the highest frequency that the color system c an resolve. The implications far normal and abnormal human color vision are discussed. (C) 2000 Optical Society of America [S0740-3232(00)00904-2] OCI S codes: 333.1710, 330.4060, 070.2590.