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Variance of high contrast textures is sensed using negative half-wave rectification
1Department of Cognitive Sciences, Institute for Mathematical Behavioral Sciences, University of California at Irvine, Irvine, CA 92697-5100, USA. cfchubb@uci.edu
Vision Research
|May 18, 2000
Summary
Human visual perception of texture contrast relies on a rectifying transformation. This study reveals that texture variance judgments depend on luminance ranges, suggesting a dominant role for the off-center system.
Area of Science:
- Visual perception
- Computational neuroscience
- Image processing
Background:
- Texture contrast perception is crucial for visual tasks.
- The underlying rectifying transformation is debated (full-wave vs. half-wave).
- Understanding luminance's role is key to visual processing models.
Purpose of the Study:
- To investigate the rectifying transformation used in texture variance judgments.
- To determine how luminance range affects texture contrast perception.
- To explore the role of the off-center system in human visual perception.
Main Methods:
- Observers judged texture variance between patches with varying luminance histograms.
- Textures comprised small squares with nine distinct luminance levels.
- Luminance ranges were manipulated (0-160 cd/m² and 60-100 cd/m²).
Main Results:
- With a wide luminance range (0-160 cd/m²), judgments used a negative half-wave rectifier, focusing on sub-mean luminances.
- With a narrow luminance range (60-100 cd/m²), most observers employed a full-wave rectifier.
- One observer consistently used a negative half-wave rectifier across conditions.
Conclusions:
- The rectifying transformation for texture variance is context-dependent, influenced by luminance range.
- Asymmetric roles of low and high luminances suggest the off-center system's significant contribution.
- Findings challenge assumptions of a uniform rectifying process in texture perception.