(a) Radial profile of ellipticity. It rises as the radius increases, peaking at the bar length and then decreasing, matching the disc’s ellipticity, shown at the top. (b) SDSS r-band image in terms of surface brightness μ_r (mag arcsec⁻²) is shown at the bottom, along with the various apertures used to represent distinct regions, such as the bulge region (red), elliptical bar region (blue), circular bar region (brown), and annular disc region (magenta) of a galaxy.