Assessing the effects of dynamic luminance contrast noise masking on a colour discrimination task on normal and deuteranomalous observers

Abstract

Traditional color vision tests use luminance contrast noise to mask cues that could improve color discrimination. Recent computerised color vision tests use dynamic luminance contrast noise to mask the colored target. The impact of such masking wasn’t yet assessed. The purpose of this work was to assess the masking effect of dynamic luminance contrast noise on the color vision detection thresholds of normal and deuteranomalous observers. The color test was developed in-house and was inspired in the Universal Color Discrimination Test (Ripamonti et al., 2013 J Vis 13(9): 1023). A video card (ViSaGe) was used to display the stimuli on a calibrated CRT monitor (GDM-F520, Sony Corp.). The stimulus was a square target of variable color on a white background both made of small circles of random diameter and packed to subtend 5 deg and 17 deg, respectively. The luminance of the circles ranged randomly from 6 to 16 cd/m². The color of the target varied along 20 directions concurrent at the color of the background. Six normal color vision and 3 deuteranomalous observers performed the test, first with static and secondly with dynamic luminance noise at 100 ms, each with three repetitions in a stair case procedure. Color discrimination thresholds were estimated and averaged across the 20 directions for static and dynamic noise on all observers. The average thresholds for static/dynamic noise were 2.77E-3(±4.58E-4)/2.64E-3(±5.71E-4) and 7.06E-3(±2.26E-3)/6.52E-3(±2.54E-3) for normal and deuteranomalous observers, respectively. Errors represent standard deviations. Wilcoxon signed-ranks test withp>0.05 in all cases showed no significant differences in-between static/dynamic conditions. The estimated differences in color thresholds with static and dynamic noise seems to indicate that there is no masking effect of dynamic luminance contrast noise on a color discrimination task on normal and deuteranomalous observers.

Meeting abstract presented at VSS 2015