Photometric classification of the 10k zCOSMOS-bright high quality sample. In the lower panel colour B − z versus redshift z is shown: blue triangles are star-forming, red squares are quiescent, green dots are red emitting galaxies. Solid line represents the evolutionary B − z track of a template Sab galaxy from Coleman et al. (1980) (Sawicki et al. 1997). In the upper panel the distributions of Δ(B − z), as defined in Eq. (3), for star-forming galaxies (blue histogram), quiescent galaxies (red histogram) and red emitting galaxies (green histogram) are plotted. The dashed line represents Δ(B − z) of the Sab galaxy evolutionary track used as separator.