The large set of detector parameters commonly used to describe performance of electronic imagers can be consolidated into a set of three indices that yield a single figure of merit. Electronic imaging has become popular in recent years, and this trend will accelerate in the future as electronic camera quality improves while the price falls. Today some digital cameras made with electronic imagers produce quality images that can compete with conventional film cameras. In essence, electronic imagers are beginning to replace film as a medium for image capture. However, user-familiar image-quality indices for electronic imagers are yet to be defined. Unlike the well-established indices for photographic films, namely modulation transfer function (MTF), ISO speed, granularity, and D-plot, which users can relate to certain image qualities, electronic imagers are usually described by a large set of detector-related parameters and users do not clearly understand the impact of these on picture quality. Imagers with larger numbers of pixels are considered to offer superior spatial resolution, for example. But in order to increase the pixel number without increasing the chip size, the size of pixel is reduced. Does this imply finer details in the resulting images? A small pixel also means less area for the photogeneration process or a loss of signal strength. In addition, smaller pixels may have higher cross-coupling, so what impact would it have on image quality? Also, how do common parameters like signal-to-noise ratio (SNR), dark current, fill factor, full-well capacity, and sensitivity interact with image quality? Is there any imager performance tradeoff involved among different categories? How can one tell which imager has a better design?
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