spatial frequency


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frequency, spatial

The rate of alternation of the luminance in a visual stimulus as a function of length, usually expressed in cycles per degree. See cycle per degree; Fourier analysis; contrast sensitivity function.
References in periodicals archive ?
The values obtained (15-85 min of arc) reveal a strong effect of spatial frequency because neurally based fusion can be achieved for disparities four to five times larger in the case of low spatial frequency stimuli.
Spatial frequency discrimination learning in normal and developmentally impaired human vision.
Perceptual contrast is affected by factors such as the degree of adaptation of the observer, the contour that defines the object, the position of the object in space, and the spatial frequency of the stimulus, understood as the number of pairs of light and dark cycles per degree of the visual angle.
1), if the stimulus containing the spatial frequency appeared first, or the right button of the mouse (no.
Among these, we highlight the notion that aging affects mostly high spatial frequency processing (10,11); contrast sensitivity alterations are significant after the age of 50 (12-14), and these alterations are due not only to changes in the optic components of the eye, but also to the neural components of visual processing (15-19).
where du/u = differential of the logarithm of the spatial frequency d(log u), [u.
Therefore, the target spread function is transformed from spatial domain to spatial frequency domain.
3) The spatial location, spatial frequency and orientation selective local information in the 2-D Gabor wavelet can well capture, thus is very suitable for two dimensional Gabor wavelet feature extraction of facial expression recognition.
Assume that the surface modulation of the elastic film has a spatial frequency of to.
A multi-focus image fusion method that applies a genetic algorithm(GA) to seek the optimal size of the sub-block has been proposed in the literature [24], in this method the visibility was chosen as the evaluation criterion to measure the clarity of the sub-blocks, and the spatial frequency is taken as a fitness function to calculate the fitness of each individual, selecting the clearest block measured by spatial frequency to construct the fused image, and then generating the optimal sub-block by selection, crossover and mutation.
Table 1: Descriptive results regarding contrast thresholds for the blue-yellow opponent channel in both groups Contrast threshold percent for athletes and (control) groups Spatial frequency Mean Maximum Minimum Standard 2 cpd * 30.

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