Kyprianidis | Jan Eric

Kyprianidis, J. E., Kang, H., & Döllner, J. (2009). Image and Video Abstraction by Anisotropic Kuwahara Filtering. Computer Graphics Forum 28, 7. Special issue on Pacific Graphics 2009.

We present a non-photorealistic rendering technique to transform colorimages and videos into painterly abstractions. It is based on a generalization of the Kuwahara filter that is adapted to the local shape of features, derived from the smoothed structure tensor. Contrary to conventional edge-preserving filters, our filter generates a painting-like flattening effect along the local feature directions while preserving shape boundaries. As opposed to conventional painting algorithms, it produces temporally coherent video abstraction without extra processing. The GPU implementation of our method processes video in real-time. The results have the clearness of cartoon illustrations but also exhibit directional information as found in oil paintings. Read More »

Kyprianidis, J. E. and Döllner, J. (2008). Image abstraction by structure adaptive filtering. In Proc. EG UK Theory and Practice of Computer Graphics, pp. 51-58.

In this work we present a framework of automatic non-photorealistic image processing techniques that create simplified stylistic illustrations from color images, videos and 3D renderings. To smooth low-contrast regions while preserving edges, we present a new fast separated implementation of the bilateral filter. Our approach works by filtering in direction of the gradient and then filtering the intermediate result in perpendicular direction. When applied iteratively, our approach does not suffer from horizontal or vertical artifacts and creates smooth output at curved boundaries. To extract salient important edges we first apply a one-dimensional difference-of-Gaussians filter in direction of the gradient and then apply smoothing along a flow field which we derive from the smoothed structure tensor. Our method creates smooth coherent output for line and curve segments. Read More »