1. A CMOS active pixel sensor, comprising: a silicon-on-insulator substrate having a top silicon layer formed on an insulator layer which is formed on a silicon substrate; a stacked pixel sensor cell, comprising: a first photodiode fabricated on said silicon substrate for sensing longer wavelength light; and a second photodiode fabricated on said top silicon layer, stacked above said first photodiode, for sensing shorter wavelength light; a pixel transistor set for said stacked pixel sensor cell, fabricated on the top silicon layer; electrical connections between each of said stacked pixel sensor cells and its pixel transistor set; and CMOS control circuitry fabricated adjacent to an array of pixel sensor cells and electrically connected thereto.