Photoreceptors are not distributed evenly on the retina. Our visual acuity is greatest at the centre of the retina: the fovea. The fovea is responsible for high acuity tasks such as reading or recognition. A retina with a uniform resolution equal to the highest fovea resolution would require 10,000 times more photoreceptors. That would require a much larger optic nerve and much larger visual cortex. Saccades move successively the fovea over regions of a scene with high information content. These saccades are partly guided by the lower resolution information gathered at the periphery of the retina. Our multiresolution sensor, the eye, provides high resolution information at selected locations, and a large field of view, with relatively little data.
Stéphane Mallat, Wavelet Tour of Signal Processing
