Accession Number : ADA334009

Title :   Exploring a Chromatic Oblique Effect.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Curran, Paul G.

PDF Url : ADA334009

Report Date : SEP 1997

Pagination or Media Count : 104

Abstract : For centuries, military forces have used camouflage to obscure potential targets from the enemy. Because the eye is fairly adept at picking out edges, colors, and bright areas, camouflage is often used to degrade these qualities from human detection. The purpose of this thesis was to investigate the role of certain spatial, temporal, and chromatic features on the human visual system and how these features may aid the quest for better camouflage. Methods: Test patterns were spatio-temporal raised cosines of varying orientation (horizontal or vertical and oblique), spatial frequency (1, 3, and 7 cpd), and modulated at 2.0 Hz. Color contrast thresholds were determined from 16 different red-green color mixture ratios. This methodology eliminates the problems with luminance artifacts and the need to determine exact equiluminance. Results: The data formed an ellipse with the half-length measuring color ldiscrimination and the half-width measuring brightness discrimination. A maximum likelihood method was used to fit the data. Three of the four subjects showed a 3 cpd chromatic oblique effect, while the 1 and 7 cpd achromatic and chromatic oblique effect was inconsistent across subjects. Conclusions: While real-world objects are more complex than laboratory stimuli, knowledge of spatial and chromatic qualities that inhibit detection will aid the quest for better camouflage.

Descriptors :   *CAMOUFLAGE, *COLORS, *LUMINANCE, SPATIAL DISTRIBUTION, MEASUREMENT, DETECTION, MAXIMUM LIKELIHOOD ESTIMATION, TEST METHODS, THESES, BRIGHTNESS, PATTERNS, VISION, STIMULI, ARTIFACTS, CHROMATICITY.

Subject Categories : Optical Countermeasures

Distribution Statement : APPROVED FOR PUBLIC RELEASE