We present a method for computer generated pen-and-ink

A new method is presented f o r watermarking digital images and video streams. This technique embeds information in a n image by changing the geometric features of the image. The method is essentially different from existing techniques in which a pseudonoise pattern is added t o the image. T h e new method has the advantage that the detection is computationally faster than existing methods. Furthermore, it is easier to detect the watermark an images that have been rotated, scaled, or distorted by a geometric transformation. The watermark is formed by a predefined dense pixel pattern, such as a collection of lines. Salient points in a n image are warped into the vicinity of the line pattern in such a way that the changes t o the image are imperceptible.

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Phong shading is one of the best known, and at the same time simplest techniques to arrive at realistic images when rendering 3D geometric models. However, despite (or maybe due to) its success and its widespread use, some aspects remain to be clarified with respect to its validity and robustness. This might be caused by the fact that the Phong method is based on geometric arguments, illumination models, and clever heuristics. In this article we address some of the fundamentals that underlie Phong shading, such as the computation of vertex normals for nonmanifold models and the adequacy of linear interpolation and we apply a new interpolation technique to achieve an efficient and qualitatively improved result.

No abstract