Flowchart of the photGalIMF code, original to the present work, which couples the galaxy chemical evolution code GalIMF (Yan et al. 2019b) with stellar evolution models to calculate photometric properties of galaxies. The GalIMF code calculates the stellar population of a galaxy for given galaxy evolution assumptions (Sect. 2.2) and a variable IMF that depends on the environment at each timestep. The metallicity, mass, and age distributions of stars are then combined with the photometric module to calculate the luminosity for selected photometric bands. See details in Sect. 2.4.