Derived limb displacement (β) in milliarcseconds and the relative limb brightness (α) in relative units are plotted for MDI roll data obtained in 2001. The distribution of points to the lower right in this graph shows the influence of data contaminated by active region faculae. They brighten and steepen the LDF to cause an apparent inward (negative) limb displacement. The solid line shows the model we use to correct the shape data using the measured brightness.