This paper gives an overview of the state-of-the-art of CMOS image sensors. The main focus is put Oil the shrinkage of the pixels : what is the effect oil the performance characteristics of the imagers and on the Various physical parameters of the camera ? How is the CMOS pixel architecture optimized to cope with the negative performance effects of the ever-shrinking pixel size ? On the other hand, the smaller dimensions in CMOS technology allow further integration oil column level and even on pixel level. This will make CMOS imagers even smarter that they are already. (C) 2008 Elsevier Ltd. All rights reserved.