Patent ID: 8184173

Claim:
A method for reading a pixel, the method comprises: generating a first signal responsive to light sensed by the pixel during a first exposure period; writing a second value to the pixel by utilizing an analog feedback circuit that comprises an analog memory cell; wherein the second value is responsive to a value of the first signal, to an analog writing process threshold that is characteristic of the writing and to a first threshold; generating a third signal responsive to the second value and to light sensed by the pixel during a second exposure period; reading a third value of the third signal; writing a fourth value to the pixel by utilizing the analog feedback circuit; wherein the fourth value is responsive to third value, to the analog writing process threshold and to the first threshold; reading the fourth value; and calculating a digital detection signal in response to the third value and in response to the fourth value; wherein the first threshold does not exceed a product of a full well value multiplied by a ratio between a length of the first exposure period and an aggregate length of the first and second exposure periods.