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Proceedings Paper

Spatial contrast sensitivity and discrimination in pictorial images
Author(s): Sophie Triantaphillidou; John Jarvis; Gaurav Gupta
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Paper Abstract

This paper describes continuing research concerned with the measurement and modeling of human spatial contrast sensitivity and discrimination functions, using complex pictorial stimuli. The relevance of such functions in image quality modeling is also reviewed. Previously1,2 we presented the choice of suitable contrast metrics, apparatus and laboratory set-up, the stimuli acquisition and manipulation, the methodology employed in the subjective tests and initial findings. Here we present our experimental paradigm, the measurement and modeling of the following visual response functions: i) Isolated Contrast Sensitivity Function (iCSF); Contextual Contrast Sensitivity Function (cCSF); Isolated Visual Perception Function (iVPF); Contextual Visual Perception Function (cVPF). Results indicate that the measured cCSFs are lower in magnitude than the iCSFs and flatter in profile. Measured iVPFs, cVPFs and cCSFs are shown to have similar profiles. Barten’s contrast detection model3 was shown to successfully predict iCSF. For a given frequency band, the reduction, or masking of cCSF compared with iCSF sensitivity is predicted from the linear amplification model (LAM)4. We also show that our extension of Barten’s contrast discrimination model1,5 is capable of describing iVPFs and cVPFs. We finally reflect on the possible implications of the measured and modeled profiles of cCSF and cVPF to image quality modeling.

Paper Details

Date Published: 3 February 2014
PDF: 15 pages
Proc. SPIE 9016, Image Quality and System Performance XI, 901604 (3 February 2014); doi: 10.1117/12.2040007
Show Author Affiliations
Sophie Triantaphillidou, Univ. of Westminster (United Kingdom)
John Jarvis, Univ. of Westminster (United Kingdom)
Gaurav Gupta, Univ. of Westminster (United Kingdom)

Published in SPIE Proceedings Vol. 9016:
Image Quality and System Performance XI
Sophie Triantaphillidou; Mohamed-Chaker Larabi, Editor(s)

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