Design and preliminary evaluation of CMOS image sensor with pseudorandom pixel placement

Pixels in conventional imaging systems are located in lattice sites, and this lattice placement of pixels causes jaggy artifacts in the image, especially at the edges of slanted lines with high-intensity contrast, which often results in severe defects in the image quality. The conventional approaches to overcoming this problem of jaggedness are to increase the number of pixels and to use anti-aliasing. However, the number of pixels is limited by the physical pixel size and the quantity of image information, while anti-aliasing intrinsically causes blurred images. The authors have been researching and evaluating image systems with pseudorandom pixel placement to reduce the effects of jaggy artifacts. We describe here the design of an image sensor that contains pixels with both pseudorandom and convectional lattice placement using an identical active pixel sensor (APS) pixel circuit. We also describe the preliminary experimental results obtained by testing the fabricated image sensors.