Receptor matrix

Light sensing (for each eyeball) is by what are locally a roughly hexagonally arranged set of light receptors set in the retina. The individual receptor spacing, however, varies progressively away from the central area of most critical vision (the fovea) - see Chapters 2.4 & 8 of 'Vision and Acquisition' for more details. The simulation SHV is primarily of the foveal or central retinal matrix, although a supplementary preprocessor enables the generation of progressively radially scaled input images such that the subsequent processing approximates to a single glimpse over the full visual field.

For photopic (daylight) viewing conditions (by colour normal observers - i.e. observers who are not ‘colour blind’) the receptors consist mainly of ones sensitive primarily to either reddish light (R cones) or greenish light (G cones), with very rare occurrence of receptors sensitive mainly to bluish light (B cones). Hence high resolution vision is essentially controlled only by the red through green part of the visible spectrum. There are, in addition, a distribution of rod receptors which are primarily sensitive to scotopic (or very low light) conditions, but consideration of the processing associated with these is specifically excluded from the following considerations.