A logarithmic CMOS digital pixel sensor

A new imaging system which competes with the human eyes is proposed. This system includes an asynchronous self-resetting digital pixel sensor array, a readout circuit and a timing control circuit. The features of human eyes, which are wide dynamic range and logarithmic response, are realized by using a new adaptive-sampling algorithm. Depends on the received illumination, the information of light intensity is transformed to digital codes at pixel level in an adaptive sampling time. An approximated logarithmic response is obtained by combining several piecewise linear responses. This is all controlled by a timing control circuit. Compared to the multiple-sampling scheme, this system offers an excellent image quality with less hardware requirement and much lower power consumption.