Simulations of the dynamic range evolution DR_s, computed from the short-exposure images as a function of the number of cycles in the photon-counting regime for various pairs in the metric-phase diversity range. The number of photons per frame is close to 1000. The co-phasing algorithm works with the data from the channel operated in the photon-counting system. DR_s evolution is measured on high flux level data. In this framework, we assume that the THT is ideal (i.e. no more instrumental defects) and that only the photon noise corrupts the short-exposure image. The metrics M₂ and M₃ are more efficient than the M1 and M4 ones and require a large PDR [ − π;π ].