Average brighter-fatter slope in the X and Y direction for the MegaCam mosaic. The observations gather all the deep field (D1) r-band images of the CFHTLS (≈1.8 M stars). The redistribution prediction is based on the mean correlations of all the CCDs; this is necessary to palliate the lack of statistics given the small frame of the flatfields data set. The prediction is compatible with the observations but with a significant uncertainty.