Normalized SNR as a function of the number of co-added cubes used for the final post-processed image. The curves were obtained by computing the spatial rms in a 20 × 20 pixels box at 3′′, 2′′ and 1′′ from the primary. Recall that in the present data one cube is composed of 1000 images with 30 ms exposure from which the 30% “best” (brightest speckle) images are selected. We overplotted the power-law that best reproduce the experimental data for 3′′ separation, namely a N^-0.4 law (dotted line). The x-axis starts at value 0, and each sub-interval represents 5 cubes.