In this work we present new weighting functions for the anisotropic Kuwahara filter. The anisotropic Kuwahara filter is an edge-preserving filter that is especially useful for creating stylized abstractions from images or videos. It is based on a generalization of the Kuwahara filter that is adapted to the local shape of features. For the smoothing process, the anisotropic Kuwahara filter uses weighting functions that use convolution in their definition. For an efficient implementation, these weighting functions are therefore usually sampled into a texture map. By contrast, our new weighting functions do not require convolution and can be efficiently computed directly during the filtering in real-time. We show that our approach creates output of similar quality as the original anisotropic Kuwahara filter and present an evaluation scheme to compute the new weighting functions efficiently by using rotational symmetries.

Photorealistic visualizations used in 3D applications designed for typical desktops usually show high visual information density. In [Kyprianidis and Döllner 2008] we present non-photorealistic image processing techniques to distill the perceptually important information and optimize the content for the limited screen space of small displays. Our method extends the approach of [Winnemöller et al. 2006] to use iterated bilateral filtering for abstraction and difference-of-Gaussians (DoG) for edge extraction by adapting it to the local orientation of the input.

We investigate stereo coherence – or consistency of stereoscopic views – in non-photorealistic rendering (NPR) by example. We designed and carried out a pilot user study that compared stereoscopic animations created using two different watercolour rendering styles. The rendering styles use image-space and object-space noise respectively. A clear majority of participants preferred the object-based technique and found it more comfortable to watch than the image-space technique which suffers from the ‘shower door effect’. Based on these preliminary results, we conclude that stereo coherence is indeed a desirable property for non-photorealistic rendering techniques.