Surface brightness and color profiles extracted by AutoProf, as described in the text: Holmberg II and IC 10 in the top row; and NGC 2403 and NGC 6744 in the bottom. The four bands are given by purple, blue, green, and red for I_E, Y_E, J_E, and H_E, respectively. The 1σ SB limits from AutoProf in units of mag arcsec^-2 are shown as dashed horizontal lines, with colors corresponding to the Euclid bands. The fluxes have been corrected for foreground extinction (Sect. 4.1) in order to be consistent with the I_E - H_E radial color gradient shown in the middle panel, and Y_E - H_E shown at the bottom. The uncorrected I_E profile is shown as a dotted (purple) curve in the top panel. The mean I_E - H_E color over typically a factor of 100 in radius in the inner galaxy is shown as a horizontal dashed line in the middle panel.