Comparison of KiDS r-band GAaP photometry to Gaia DR1 G-band and SDSS DR9 r-band photometry. Stars with dereddened g − i colours, based on colour-calibrated KiDS GAaP data (x-axis), between 0.2 and 1.5 are selected to iteratively derive the median photometric offsets (r − G)₀ (left sequence) and (r − r_SDSS) (right sequence). The latter sequence of data points is shifted by 1.6 mag in (g − i)₀ for clarity. The red and green outlines show the regions encompassing the data points used in the final iteration of each fit.