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Does resolution really increase image quality?
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Paper Abstract

A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger limiting resolution which is derived from the Modulation Transfer Function (MTF). But recent sensor technologies (1.75μm, and soon 1.45μm) with typical aperture f/2.8 are clearly reaching the size of the diffraction blur spot. A second example is the impact on pixel light sensitivity and image sensor noise. For photonic noise, the Signal-to-Noise-Ratio (SNR) is typically a decreasing function of the resolution. To evaluate whether shrinking pixel size could be beneficial to the image quality, the tradeoff between spatial resolution and light sensitivity is examined by comparing the image information capacity of sensors with varying pixel size. A theoretical analysis that takes into consideration measured and predictive models of pixel performance degradation and improvement associated with CMOS imager technology scaling, is presented. This analysis is completed by a benchmarking of recent commercial sensors with different pixel technologies.

Paper Details

Date Published: 3 March 2008
PDF: 12 pages
Proc. SPIE 6817, Digital Photography IV, 68170Q (3 March 2008); doi: 10.1117/12.766150
Show Author Affiliations
Christel-Loïc Tisse, DxO Labs. (France)
Frédéric Guichard, DxO Labs. (France)
Frédéric Cao, DxO Labs. (France)

Published in SPIE Proceedings Vol. 6817:
Digital Photography IV
Jeffrey M. DiCarlo; Brian G. Rodricks, Editor(s)

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