Color coding in the cortex: a modified approach to bottom-up visual attention.

Itti and Koch's (Vision Research 40:1489-1506, 2000) saliency-based visual attention model is a broadly accepted model that describes how attention processes are deployed in the visual cortex in a pure bottom-up strategy. This work complements their model by modifying the color feature calculation. Evidence suggests that S-cone responses are elicited in the same spatial distribution and have the same sign as responses to M-cone stimuli; these cells are tentatively referred to as red-cyan. For other cells, the S-cone input seems to be aligned with the L-cone input; these cells might be green-magenta cells. To model red-cyan and green-magenta double-opponent cells, we implement a center-surround difference approach of the aforementioned model. The resulting color maps elicited enhanced responses to color salient stimuli when compared to the classic ones at high statistical significance levels. We also show that the modified model improves the prediction of locations attended by human viewers.