Illustration of the differential reddening correction towards NGC 1751. Panel (a) shows the original uncorrected m_F814W vs m_F435W − m_F814W CMD of well-measured stars. Also shown as a red arrow is the direction of the reddening vector. Panel (b) shows the same CMD after the corrections for the effects of differential reddening have been applied. Panel (c) presents the resulting reddening map. The grey contours follow the density distribution of the reference stars used for the correction.