Nielsen, K. R. K.
Overview
Works:  2 works in 6 publications in 1 language and 6 library holdings 

Roles:  Author 
Classifications:  Q335.M41, 
Publication Timeline
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Most widely held works by
K. R. K Nielsen
ZeroCrossings and Spatiotemporal Interpolation in Vision: Aliasing and Electrical Coupling between Sensors by
Tomaso Poggio(
Book
)
4 editions published in 1982 in English and held by 4 WorldCat member libraries worldwide
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) zerocrossings are detected independently in the output of each of these channels. Zerocrossings 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 zerocrossing results is proved for the case of Fourier polynomials an extension of Logan's theorem to 2dimensional 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
4 editions published in 1982 in English and held by 4 WorldCat member libraries worldwide
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) zerocrossings are detected independently in the output of each of these channels. Zerocrossings 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 zerocrossing results is proved for the case of Fourier polynomials an extension of Logan's theorem to 2dimensional 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
Vertical image registration in stereopsis by
K. R. K Nielsen(
Book
)
2 editions published in 1983 in English and held by 2 WorldCat member libraries worldwide
2 editions published in 1983 in English and held by 2 WorldCat member libraries worldwide
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