Apparatus for discerning the noticeable presence of spatial fluctuations of intensity within a two-dimensional visual field
First Claim
1. Apparatus for discerning, within at least a certain section of a two-dimensional spatial field of intensities, the noticeable presence, along a given field dimension, of intensity variations having spatial frequencies within a predetermined limited spatial frequency band, the given length of said certain section along said given field dimension being equal to more than one wavelength of the lower limit spatial frequency of said limited band;
- said apparatus comprising;
first means for sequentially convolving said spatial field at each of a plurality of uniformly-spaced intervals along said given field dimension of said certain section with at least one given kernel function, each given kernel function being characterized by (1) having a limited spatial extent along said given field dimension which is substantially smaller than said given length of said given field dimension of said certain section (2) having an integrated value over its limited spatial extent substantially equal to zero and (3) exhibiting a spatial frequency passband no greater than said predetermined limited spatial frequency band, andsecond means for deriving an output signal equal to the value of the q'"'"'th root of the sum of the q'"'"'th power of each of the respective convolutions, and comparing this signal with a predetermined threshold value, where q is a given-valued number and where said predetermined threshold value corresponds to a just-noticeable presence of intensity variations having spatial frequencies within said kernel function spatial frequency band along the length of said given field of said certain section.
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Abstract
The spatial field is sequentially convolved at each of a plurality of uniformly-spaced intervals along a field dimension with a given type of limited spatial extent kernel function which preferably has a one-octave spatial bandwidth. Convolution combining means derives an output only if the q'"'"'th power of the sequential convolutions exceed a threshold corresponding to the just-noticeable presence of spatial frequencies within the spatial bandwidth of the kernel function.
34 Citations
22 Claims
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1. Apparatus for discerning, within at least a certain section of a two-dimensional spatial field of intensities, the noticeable presence, along a given field dimension, of intensity variations having spatial frequencies within a predetermined limited spatial frequency band, the given length of said certain section along said given field dimension being equal to more than one wavelength of the lower limit spatial frequency of said limited band;
- said apparatus comprising;
first means for sequentially convolving said spatial field at each of a plurality of uniformly-spaced intervals along said given field dimension of said certain section with at least one given kernel function, each given kernel function being characterized by (1) having a limited spatial extent along said given field dimension which is substantially smaller than said given length of said given field dimension of said certain section (2) having an integrated value over its limited spatial extent substantially equal to zero and (3) exhibiting a spatial frequency passband no greater than said predetermined limited spatial frequency band, and second means for deriving an output signal equal to the value of the q'"'"'th root of the sum of the q'"'"'th power of each of the respective convolutions, and comparing this signal with a predetermined threshold value, where q is a given-valued number and where said predetermined threshold value corresponds to a just-noticeable presence of intensity variations having spatial frequencies within said kernel function spatial frequency band along the length of said given field of said certain section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- said apparatus comprising;
Specification