Zero-Crossings and Spatiotemporal Interpolation in Vision: Aliasing and Electrical Coupling between Sensors.
Abstract
We will briefly outline a computational theory of the first stages of human vision according to which; (a) the retinal image is filtered by a set of centresurround receptive fields (of about 5 different spatial sizes) which are approximately bandpass in spatial frequency; and (b) zero-crossings are detected independently in the output of each of these channels. Zero-crossings in each channel are then a set of discrete symbols which may be used for later processing such as contour extraction and stereopsis. A formulation of Logan's zero-crossing results is proved for the case of Fourier polynomials an extension of Logan's theorem to 2-dimensional functions is also proved. Within this framework, we shall describe an experimental and theoretical approach (developed by one of us with M. Fahle) to the problem of visual acuity and hyperacuity of human vision. The positional accuracy achieved, for instance, in reading a vernier is astonishingly high, corresponding to a fraction of the spacing between adjacent photoreceptors in the fovea. Stroboscopic presentation of a moving object can be interpolated by our visual system into the perception of continuous motion; and this 'spatiotemporal' interpolation also can be very accurate. It is suggested that the known spatiotemporal properties of the channels envisaged by the theory of visual processing outlined above implement an interpolation scheme which can explain human vernier acuity for moving targets.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1982
- Accession Number
- ADA117608
Entities
People
- H. K. Nishihara
- K. R. K. Nielsen
- T. Poggio
Organizations
- Massachusetts Institute of Technology