Illumination with a spot having 100 ke⁻ in pixel maximum and a Gaussian shape with a rms of 1.6 pixel results in boundary displacements (multiplied by a factor 5, red lines) that depend on the distribution of charges within surrounding pixels (colored circles). The displacements between the intial boundaries (black) and their final positions (red) correspond to the δ^X terms of our model. It shows that the central pixel effective size shrinks as illumination increases, while pixels away from spot center tend to grow.