Adaptation (eye) opsin photopigment. The various cone cells are maximally sensitive to either short wavelengths (blue light), medium wavelengths (green light), or long wavelengths (red light). Rod photoreceptors only contain one type of photopigment, rhodopsin, which has a peak sensitivity at a wavelength of approximately 530 nanometers which corresponds to blue-green light. A minor mechanism of adaptation is the pupillary light reflex, adjusting the amount of light that reaches the retina. In response to varying ambient light levels, rods and cones of eye function both in isolation and in tandem to adjust the visual system. Changes in the sensitivity of rods and
Retina 500,000 bits per second (for more information on bits, see information theory) without colour or around 600,000 bits per second including colour. When the retina sends neural impulses representing an image to the brain, it spatially encodes (compresses) those impulses to fit the limited capacity of the optic nerve. Compression is necessary because there are 100 times more photoreceptor cells than ganglion cells. This is done by "decorrelation", which is carried out by the "centre–surround structures", which are implemented by the bipolar and ganglion cells. There are two types of centre–surround structures in the retina – on-centres and off-centres. On-centres