Area 17

What I believe to be one of the most important areas of onward visual processing, if not the most important, is what is known as Area 17 of the Striate Cortex. In this area - first thoroughly studied as recently as the mid 1970's, particularly by D.H. Hubel & T.N. Wiesel - local groups of partial difference signal streams interact along essentially linear axes at roughly 30 degree orientation differences, these interactions occurring for data from each separate eye & from the two eyes combined and also for the various chromatic arrangements (see, for instance, Chapters 3.8 & 3.14 of ‘Computer Vision ...’).

The resultants from these local 1D interactions, taken in conjunction with the circularly symmetric, softened receptive fields due to the optical blur & the retinal Laplacian-like interaction, is the generation of a set of elliptical receptive fields such that it is readily possible to derive the local orientation of image discontinuities to a high level of accuracy (see Chapter 4.2.2.5 of 'Computer Vision ...'). Having established the local orientation of discontinuities, it then becomes equally readily possibly to determine the sub-pixel location of a discontinuity at a given pixel from the centre of the addressed pixel in polar co-ordinates (Chapter 4.2.2 of 'Computer Vision ...').