Central surface brightness μ₀ versus scale-length h for the disk (or exponential) component of the different Hubble types. The linear fit obtained for E and cD types (upper left panel) is shown in all panels as solid lines, along with the parallel dashed lines at ±3 times the rms dispersion in μ₀ around the fit. Points are color-coded with the g − r color of the disk (or exponential) component. For all lenticular types as well as early and intermediate spirals up to Scd, h is correlated with μ₀ with different intercept values, but a common slope would be an acceptable approximation to each distribution. For Sdm and Sm late-type spirals, the distribution is more dispersed.