Anisotropic shock filter for enhancement and non-photorealistic generation of flow patterns

An anisotropic shock filter is presented for edge-preserving enhancement of flow patterns in images. The filter consists of an anisotropic smoothing filter and a shock filter. Edges in images are sharpened in the direction of the principal eigenvector of the structure tensors. The filter is suitable for enhancing and visualizing flow patterns in images. This characteristic of the filter is used for actively generating flow patterns in images, and this technique is applied to non-photorealistic rendering for transforming photographs into oil-painting-like images or crayon-scratch-like pictures.