Figure A.6.

Impact of spatial summation. Contrast sensitivity functions computed for different sizes of Gabor patches: (A) 3.3 cycles, (B), 1.7 cycles, (C) 0.4 cycles. Red disks depict computational observer performance assessed at the level of cone photocurrents, in the presence of fixational eye movements, and computed using the SVM-Template-Energy inference engine. Gray triangles: performance of the two subjects measured by Crowell and Banks. Subject JAC (light gray triangles) has a lower high frequency sensitivity than subject MSB, and was not able to detect stimuli of certain patch size and spatial frequencies at any contrast. The simulated stimulus conditions (matched to the experiment of Crowell and Banks) were: 100 cd/m² mean luminance, 100 ms pulsed stimulus presentation, 2.5 mm pupil size, and performance threshold set to 75% correct.