It has often been conjectured that the effectiveness of line drawings can be explained by the similarity of edge images to line drawings. This article presents several problems with explaining line drawing perception in terms of edges, and how the recently proposed Realism Hypothesis resolves these problems. There is nonetheless existing evidence that edges are often the best features for predicting where people draw lines; this article describes how the Realism Hypothesis can explain this evidence.
Keywords: line drawing; perception of art, shape perception, abstracted shading, edge processing.