Surface flows for image-based shading design

We present a novel method for producing convincing pictures of shaded objects based entirely on 2D image operations. This approach, which we call image-based shading design , offers direct artistic control in the picture plane by deforming image primitives so that they appear to conform to specific 3D shapes. Using a differential analysis of reflected radiance, we identify the two types of surface flows involved in the depiction of shaded objects, which are consistent with recent perceptual studies. We then introduce two novel deformation operators that closely mimic surface flows while providing direct artistic controls in real-time.