Figure 3
Maximum likelihood photon number thresholding method. An example of the maximum likelihood method to estimate the number of photons in a pixel for (a) pixels with low readout noise, and (b) pixels with a large readout noise. In the case of the pixel with a low readout noise the peaks corresponding to different photon numbers are well resolved and thresholds to distinguish the number of photon events that were detected by that pixel can be well estimated using the maximum likelihood method. In the case of pixels with high readout noise the thresholds are set higher than for those pixels with a low readout noise through the implementation of the maximum likelihood method. Implementing this method that considers the pixel readout noise reduces the number of false positives for one-photon and two-photon events, however, this will also result in an increase in the number of false negatives for these events as can be seen in the overlap of the red (zero-photon events) and orange (one-photon event) curves in (b).
