Photon counting electronics and method that allow for counting single photons with sensitivity, linearity, and accuracy. The method for accurately counting photon numbers entering a photon multiplier tube comprising the steps of counting the number of the electrical pulses generated by photons; measuring the duration of the electrical pulses with a timing clock, wherein the timing clock can count the number of temporally overlapped photons; measuring the intensity of the electrical pulses with an intensity discriminator, wherein the intensity discriminator can count the number of intensity-overlapped photons; and summing the number of the electrical pulses, the number of temporally overlapped photon, and the number of intensity-overlapped photons, that is equal to the total number of photons.