ABSTRACT
The cells of layer 4 of visual area V1 were labeled simple cells by Hubel and Wiesel. This label refers to the fact that the receptive fields of these cells all code for simple visual features such as lines and edges. The most important form of depth information in humans comes from retinal disparity. This is the fact that the images from two objects that are at different distances do not fall on the same parts of the retinas of the two eyes. Coding for color not only occurs through the differential responding of the three types of cone and by the opponent processes in the lateral geniculate nucleus. It also occurs in the visual cortex. Blobs are also opponent-color cells that are either red–green or blue–yellow. Even so, color perception is a global perception of the whole visual scene.
