Photometric redshift results as a function of the r magnitude and the i − z colour. These results were obtained with a 100-fold cross-validation strategy on the galaxy set with the five magnitudes available (𝒯₅). Left panel: average standard deviation of the redshifts of the nearest neighbours σ(z_NN), middle panel: rms of the actual error z_phot − z_spec, and right panel: average estimated errors δ_zphot. The colour scale and the black contours are set as in Fig. 6.