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Texture Optimization for Example-based Synthesis ( Project page | PDF ) Vivek Kwatra, Irfan Essa, Aaron Bobick, and Nipun Kwatra  To Appear in SIGGRAPH 2005

We present a novel technique for texture synthesis using optimization. We define a Markov Random Field (MRF)-based similarity metric for measuring the quality of synthesized texture with respect to a given input sample. This allows us to formulate the synthesis problem as minimization of an energy function, which is optimized using an Expectation Maximization (EM)-like algorithm. In contrast to most example-based techniques that do region-growing, ours is a joint optimization approach that progressively refines the entire texture. Additionally, our approach is ideally suited to allow for controllable synthesis of textures. Specifically, we demonstrate controllability by animating image textures using flow fields. We allow for general two-dimensional flow fields that may dynamically change over time. Applications of this technique include dynamic texturing of fluid animations and texture-based flow visualization.

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Graphcut Textures: Image and Video Synthesis Using Graph Cuts ( Project page ) Vivek Kwatra, Arno Schödl, Irfan Essa, Greg Turk, and Aaron Bobick Proc. ACM Transactions on Graphics, SIGGRAPH 2003

In this paper we introduce a new algorithm for image and video texture synthesis. In our approach, patch regions from a sample image or video are transformed and copied to the output and then stitched together along optimal seams to generate a new (and typically larger) output. In contrast to other techniques, the size of the patch is not chosen a-priori, but instead a graph cut technique is used to determine the optimal patch region for any given offset between the input and output texture. Unlike dynamic programming, our graph cut technique for seam optimization is applicable in any dimension. We specifically explore it in 2D and 3D to perform video texture synthesis in addition to regular image synthesis. We present approximative offset search techniques that work well in conjunction with the presented patch size optimization. We show results for synthesizing regular, random, and natural images and videos. We also demonstrate how this method can be used to interactively merge different images to generate new scenes.

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2D Cel Animation Compression ( Project page )

Space-Time Surface Simplification and Edgebreaker Compression for 2D Cel Animations Vivek Kwatra and Jarek Rossignac International Journal on Shape Modeling, Volume8, Number 2, December 2002

Surface Simplification and Edgebreaker Compression for 2D Cel Animations Vivek Kwatra and Jarek Rossignac Proc. International Conference on Shape Modeling and Applications (SMI 2002)

Digitized cel animations are typically composed of frames, which contain a small number of regions, which each contain pixels of the same color and exhibit a significant level of shape coherence through time. To exploit this coherence, we treat the stack of frames as a 3D volume and represent the evolution of each region by the bounding surface of the 3D volume V that it sweeps out. To reduce transmission costs, we triangulate and simplify the bounding surface and then encode it using the Edgebreaker compression scheme. To restore a close approximation of the original animation, the client player decompresses the surface and produces the successive frames by intersecting V with constant-time planes. The intersection is generated in real-time with standard graphics hardware through an improved capping (i.e. solid clipping) technique, which correctly handles overlapping facets. We have tested this approach on real and synthetic black&white animations and report compression ratios that improve upon those produced using the MPEG, MRLE, and GZIP compression standards for an equivalent quality result.

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