DISPARITY MODULATION SENSITIVITY FOR NARROW-BAND-FILTERED STEREOGRAMS

Stereo thresholds for 84% correct detection of sinusoidal disparity co rrugations depicted by narrow-band-filtered random dot stereograms wer e determined for surfaces as a function of (i) luminance centre spatia l frequency and (ii) disparity modulation frequency. In addition, supr athreshold depth matching functions for two amplitudes of peak-to-trou gh depth were determined using similar stimuli. Disparity thresholds f ollowed a U-shaped function when plotted against luminance centre spat ial frequency from 1 to 8 c/deg. The threshold functions for the three highest corrugation frequencies (ranging from 0.25 to 1 c/deg) formed a single family with a similar bandpass shape and a peak sensitivity at ca 4 c/deg. At the lowest frequency of depth modulation (0.125 c/de g) the shape of the luminance spatial frequency threshold function sho wed a reduced sensitivity to depth modulations when portrayed by patte rns with high luminance centre frequencies (8 c/deg), The similarity o f the threshold functions reveals luminance and corrugation frequency to be largely independent dimensions. The finding that the functions a re not identical provides some evidence to support a weak luminance sp atial frequency selectivity in stereoscopic channels tuned to corrugat ion frequency. (C) 1997 Elsevier Science Ltd.