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Scaling effects in the perception of higher-order spatial correlations
J S Joseph1, J D Victor, L M Optican
1Laboratory of Sensorimotor Research, National Eye Institute, NIH, Bethesda, MD 20892, USA. jsj@unr.edu
Vision Research
|February 17, 1998
Summary
Human texture discrimination is scale-invariant when textures are literally scaled. However, performance varies with scale when display size is constant, suggesting efficient processing of fewer texture elements.
Area of Science:
- Visual perception
- Computational neuroscience
- Image analysis
Background:
- Human texture discrimination relies on spatial frequency and higher-order correlations.
- Scale invariance is known for spatial frequency but not for higher-order correlations.
Purpose of the Study:
- Investigate the scale dependence of texture discrimination for higher-order correlations.
- Determine how scaling affects human sensitivity to texture structure.
Main Methods:
- Used image ensembles with identical power spectra but varying higher-order correlations.
- Manipulated texture scale by literal scaling and constant display size.
- Computed ideal observer performance and human observer efficiency.
Main Results:
- Discrimination performance was scale-invariant when textures were literally scaled over 3 octaves.
- Performance varied with scale when display size was constant.
- Human efficiency was higher for textures with stronger correlations and fewer elements.
- Efficiency decreased as texture elements increased within a fixed display.
Conclusions:
- Human texture discrimination exhibits scale-invariant properties for certain aspects.
- Processing efficiency is linked to the number of texture elements and their correlation strength.
- A model suggests scale-invariant processing of a fixed number of elements and less efficient processing of the rest.