Performance of iEFC as a function of photon flux. The top figure shows the Strehl ratio as a function of calibration flux after closed-loop control and, the bottom figure shows the median contrast as a function of calibration flux. Both the Strehl ratio and contrast are measured after a number of closed-loop iterations. Each line corresponds to a different number of iterations. The brightest green (blue) shows the Strehl ratio (contrast) after 10 iterations while the darkest green (blue) shows the Strehl ratio (contrast) after 100 iterations. A large improvement is visible if enough photons are used to calibrate the system matrix. The achieved performance converges when roughly 10¹⁰ photons per calibration frame are used.