The mainstream in image sensors for high-end studio photography has been 6-megapixel CCDs, and the market is now adopting 16.8-megapixel image sensors as the new reference standard. The semiconductor processes used to manufacture sensors can achieve increasingly smaller pixels and larger sensors for even higher-density chips. The market requirements for image quality and the practical considerations of camera systems, however, must be understood to answer the question: What will be the "ultimate" image sensor of days to come? Marketplace dynamics will strongly drive the evolution of image sensors. It's relatively easy to conceive of imagers approaching 100 megapixels that deliver extraordinary image quality, but could such devices achieve commercial success? Chip makers face such concerns as process technology, pixel and chip size, and the number of chips per wafer. Camera makers are concerned with sensitivity (effective film speed), dynamic range, noise, compatibility with camera formats and legacy lenses, and, of course, price…