Image Sensor with Controllable Exposure Response Non-Linearity

An image sensor comprising:

• an array of pixels, each pixel configured to accumulate photocharge corresponding to photoconversion of photons incident on the pixel;
• readout circuitry configured to discriminate individual photocharge, wherein the readout circuitry includes an analog-to-digital converter (ADC) configured to generate a digital signal having a maximum integer bit depth of nmax corresponding to a value of (2nmax−1), and wherein the value of the digital signal output by the readout circuitry for each pixel readout is (i) an integer number equal to the corresponding number of individual accumulated photocharge being readout when the number of individual accumulated photocharge being readout is between 0 and (2nmax−1), inclusive, and (ii) (2nmax−1) when the number of individual accumulated photocharge being readout is greater than (2nmax−1);
• and
• a controller comprising at least one of hardware, software, and firmware configured to selectively adjust the non-linearity of the exposure response of the image sensor, wherein the non-linearity of the exposure response is based on photon arrival statistics;
• and
• wherein the least-significant-bit (LSB) of the ADC corresponds to no more than one photoelectron independent of the non-linearity of the exposure response being selectively adjusted, single-photon sensitivity and resolution thereby being maintained while varying the exposure response.