respective values stored by capacitors 322 and 330 are compared and the difference between the two voltage levels indicates the level of exposure of the photodiode 304 to the incident light horizontal bus 312 and horizontal bus 314 are fed into respective inputs of a differential amplifier 355 when respective column select switches 360 365 are closed the output of the differential amplifier 355 is fed into an analog to digital converter adc 370 for converting the analog difference signal into a digital value the output of adc 370 is fed into a pixel processor 375 for additional processing which may include compression of the digital values forming of the resulting image processing of damaged pixels etc the output of the pixel processor is fed into an output circuit 380 the output of which is then forwarded to additional processing e g the data may then be forwarded to the peripheral bus 410 of fig4 fig3 also depicts the pixel sensor array 350 as being integrated onto or within a chip 380 the chip 380 may be made of any material suitable for use with pixel sensor arrays including silicon based materials glass based materials etc fig4 shows system 400 a typical processor based system modified to include an image sensor ic as in fig3 processor based systems exemplify systems of digital circuits that could include an image sensor examples of processor based systems include without limitation computer systems camera systems scanners machine vision systems vehicle navigation systems video telephones surveillance systems auto focus systems star tracker systems motion detection systems image stabilization systems and data compression systems for high definition television any of which could utilize the invention system 400 includes central processing unit cpu 402 that communicates with various devices over bus 404 some of the devices.