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Proceedings Paper

Digital zoom for low-vision enhancement systems
Author(s): Rajashekar Venkatachalam; J. Graham Strong; Winnie Wong; Richard I Hornsey
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Paper Abstract

Zoom magnification is an essential element of video-based low vision enhancement systems. However, since optical zoom systems are bulky and power intensive, digital zoom is an attractive alternative. This paper determines the visual acuity of 15 subjects when a letter chart is viewed through a video system with various levels of digital zoom. A strategy in which the 1:1 magnified image is obtained by combining optical magnification with digital minification gives the best result, provided background scene information is know from the other cameras. A real-time FPGA based system for simultaneous zoom and smoothing is also demonstrated for text reading and enhancement.

Paper Details

Date Published: 7 June 2004
PDF: 10 pages
Proc. SPIE 5292, Human Vision and Electronic Imaging IX, (7 June 2004); doi: 10.1117/12.522183
Show Author Affiliations
Rajashekar Venkatachalam, Univ. of Waterloo (Canada)
J. Graham Strong, Univ. of Waterloo (Canada)
Winnie Wong, York Univ. (Canada)
Richard I Hornsey, York Univ. (Canada)

Published in SPIE Proceedings Vol. 5292:
Human Vision and Electronic Imaging IX
Bernice E. Rogowitz; Thrasyvoulos N. Pappas, Editor(s)

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