Rest-frame colour–colour plane F365 − F551 versus F551 − J for the 76642 ALHAMBRA galaxies with F814W ≤ 23 at z < 1.5. This plane is equivalent to the commonly used UVJ diagram, and the quiescent selection box from the literature (Williams et al. 2009) is delimited by dashed lines. The coloured lines show level contours in the density of galaxies, starting at 0.1 galaxies dex⁻² and increasing in 0.6 galaxies dex⁻² steps. Red contours show the quiescent population, and blue contours show the star-forming population, as defined by DG17. The side panels show the normalised distribution in F365 − F551 (right panel) and F551 − J (top panel). In both panels the total distribution is presented in black, the quiescent population in filled red, and the star-forming population in filled blue.