Maps of photometric corrections (relative to the twilight flat-field). Each panel displays a low resolution map (36 × 36 super-pixels of 256 × 256 real pixels, i.e. a resolution of about 2′) of the corrections. Those corrections are determined on dithered observations of dense stellar fields in a given photometric band. Observations for the corrections displayed in u_Mg_Mr_Mi_M and z_M panels have been obtained during the same night in 2005 under remarkably stable atmospheric conditions. The i2_M panel displays the result of an observation taken in 2008, about 1 year after the replacement of the i_M filter. CCD boundaries are figured by white dotted lines.