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Proceedings Paper

Pixel-level processing: why, what, and how?
Author(s): Abbas El Gamal; David X. D. Yang; Boyd A. Fowler
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Paper Abstract

Pixel level processing promises many significant advantages including high SNR, low power, and the ability to adapt image capture and processing to different environments by processing signals during integration. However, the severe limitation on pixel size has precluded its mainstream use. In this paper we argue that CMOS technology scaling will make pixel level processing increasingly popular. Since pixel size is limited primarily by optical and light collection considerations, as CMOS technology scales, an increasing number of transistors can be integrated at the pixel. We first demonstrate that our argument is supported by the evolution of CMOS image sensor from PPS to APS. We then briefly survey existing work on analog pixel level processing an d pixel level ADC. We classify analog processing into intrapixel and interpixel. Intrapixel processing is mainly used to improve sensor performance, while interpixel processing is used to perform early vision processing. We briefly describe the operation and architecture of our recently developed pixel level MCBS ADC. Finally we discuss future directions in pixel level processing. We argue that interpixel analog processing is not likely to become mainstream even for computational sensors due to the poor scaling popular since it minimizes analog processing, and requires only simple and imprecise circuits to implement. We then discuss the inclusion of digital memory and interpixel digital processing in future technologies to implement programmable digital pixel sensors.

Paper Details

Date Published: 22 March 1999
PDF: 12 pages
Proc. SPIE 3650, Sensors, Cameras, and Applications for Digital Photography, (22 March 1999); doi: 10.1117/12.342849
Show Author Affiliations
Abbas El Gamal, Stanford Univ. (United States)
David X. D. Yang, Stanford Univ. (United States)
Boyd A. Fowler, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 3650:
Sensors, Cameras, and Applications for Digital Photography
Nitin Sampat; Thomas Yeh, Editor(s)

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