Photometric vs stellar population-based ellipticities. The mean ellipticity of the metallicity (orange), [Mg/Fe] (green), and IMF slope maps (blue) is shown as a function of the photometric ellipticity. Stellar population-based ellipticities are higher than the photometric ones and the difference is larger for the metallicity and the [Mg/Fe] maps than for the IMF slope ones, hinting toward a different internal distribution of IMF slope and chemical enrichment values.