Perceived Contrast and Stimulus Size: Experiment and Simulation

Abstract

Perceived contrast functions were determined for three different Gabor patch sizes using magnitude estimation and verified by contrast matching. While thresholds show a significant decrease with decreasing patch size, perceived contrasts are equal and independent of patch size for contrasts above 0.06. Contrast matching was also used to study the apparent contrast of two other spatially limited stimuli; the sum of two orthogonal 4 c/deg sine waves multiplied by a gaussian envelope and the sum of spatially adjacent positive and negative gaussians. Models of contrast perception, based on tuned Gabor spatial filters, were formulated and tested for agreement with our experimental data. A model that pools filter responses across spatial frequencies and orientations was found to be more in agreement with our data than a model that simply uses the response of a single, maximally excited, mechanism to mediate contrast perception. Optimum filter bandw was found to be about 1.1 octaves. Keywords: Contrast perception; Spatial filtering; Visual modelling; Reprints.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1988
Accession Number
ADA204952

Entities

People

  • Mark W. Cannon
  • Steven C. Fullenkamp

Organizations

  • Armstrong Laboratory

Tags

Communities of Interest

  • Biomedical
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Agreements
  • Bandwidth
  • Computers
  • Contrast
  • Data Analysis
  • Detection
  • Detectors
  • Experimental Data
  • Frequency
  • Image Processing
  • Orientation (Direction)
  • Perception
  • Simulations
  • Sine Waves
  • Spatial Filtering
  • Two Dimensional
  • Waves

Readers

  • Approximation Theory.
  • Vision Science/Vision Psychology/Cognitive Neuroscience.