Ratio between the radial surface density profile of the mass and the luminosity of the galaxy, calculated with bins with an equal number of particles, as a function of cylindrical radius R of the IllustrisTNG galaxy. The black solid line is the mass-luminosity relation considering all the stellar particles. The solid lines correspond to the mass-luminosity relation for spheroids identified with the six methods of dynamic decomposition, while the dashed line corresponds to the discs. The dotted line represents the one-to-one ratio of these quantities.