Figure 4.

Impact of phototransduction. Contrast sensitivity functions computed at the level of cone photopigment excitations (gray disks) and at the level of cone photocurrents (red disks) in the absence of fixational eye movements. Here, CSFs were obtained using the SVM-Template-Linear computational observer for a 3 mm pupil, typical subject wavefront-based optics, and eccentricity-based cone mosaics. The transformation from cone photopigment excitations to cone photocurrent results in a sensitivity loss of a factor of 2 to 2.5. Note that this sensitivity loss is specific to mean light level (here 34 cd/m²) and stimulus duration (here 100 ms). Stimuli presented at different adapting light levels and/or for different durations will be affected differently (see Appendix Figures A3 and A5).