Left: relative difference between the calibrated and CLV-corrected image with our method and the original image (within 0.98 R) for all the synthetic data of subset 8. rms difference (green), mean absolute difference (blue), mean difference (orange) and maximum difference (red). Each of these values refers to a single image at a time (for example the difference averaged over all pixels, or the maximum value found in one pixel of the image). These differences are plotted vs. the date on which the original Rome/PSPT images (that were randomly distorted) were recorded. Note that the maximum difference values have been divided by ten to plot them on the same scale as the other quantities. The solid lines are 100 point averages (that is averages over the values obtained for 100 images) and the shaded surfaces denote the asymmetric 1σ interval. Right: distribution of the relative difference values.