We explore creating ""cliplets"", a form of visual media that juxtaposes still image and video segments, both spatially and temporally, to expressively abstract a moment. Much as in ""cinemagraphs"", the tension between static and dynamic elements in a cliplet reinforces both aspects, strongly focusing the viewer's attention. Creating this type of imagery is challenging without professional tools and training. We develop a set of idioms, essentially spatiotemporal mappings, that characterize cliplet elements, and use these idioms in an interactive system to quickly compose a cliplet from ordinary handheld video. One difficulty is to avoid artifacts in the cliplet composition without resorting to extensive manual input. We address this with automatic alignment, looping optimization and feathering, simultaneous matting and compositing, and Laplacian blending. A key user-interface challenge is to provide affordances to define the parameters of the mappings from input time to output time while maintaining a focus on the cliplet being created. We demonstrate the creation of a variety of cliplet types. We also report on informal feedback as well as a more structured survey of users.

We present a new technique for interactive relighting of dynamic refractive objects with complex material properties. We describe our technique in terms of a rendering pipeline in which each stage runs entirely on the GPU. The rendering pipeline converts surfaces to volumetric data, traces the curved paths of photons as they refract through the volume, and renders arbitrary views of the resulting radiance distribution. Our rendering pipeline is fast enough to permit interactive updates to lighting, materials, geometry, and viewing parameters without any precomputation. Applications of our technique include the visualization of caustics, absorption, and scattering while running physical simulations or while manipulating surfaces in real time.

We investigate the general problem of reproducing color images on an offset press using custom inks in any combination and number.While this problem has been explored previously for the case of two inks, there are a number of new mathematical and algorithmic challenges that arise as the number of inks increases.These challenges include more complex gamut mapping strategies, more efficient ink selection strategies, and fast and numerically accurate methods for computing ink separations in situations that may be either over-or under-constrained.In addition, the demands of high-quality color printing require an accurate physical model of the colors that result from overprinting multiple inks using halftoning, including the effects of trapping, dot gain, and the interreflection of light between ink layers.In this paper, we explore these issues related to printing with multiple custom inks, and address them with new algorithms and physical models.Finally, we present some printed examples demonstrating the promise of our methods.

We present a new clustering algorithm for global illumination in complex environments. The new algorithm extends provious work on clustering for radiosity to allow for nondiffuse (glossy) reflectors. We represent clusters as points with directional distributions of outgoing and incoming radiance and importance, and we derive an error bound for transfers between these clusters. The algorithm groups input surfaces into a hierarchy of clusters, and then permits clusters to interact only if the error bound is below an acceptable tolerance. We show that the algorithm is asymptotically more efficient than previous clustering algorithms even when restricted to ideally diffuse environments. Finally, we demonstrate the performance of our method on two complex glossy environments.

We investigate a new approach for reproducing color images. Rather than mapping the colors in an image onto the gamut of colors that can be printed with cyan, magenta, yellow, and black inks, we choose the set of printing inks for the particular image being reproduced. In this paper, we look at the special case of selecting inks for duotone printing, a relatively inexpensive process in which just two inks are used. Specifically, the system we describe takes an image as input, and allows a user to select 0, 1, or 2 inks. It then chooses the remaining ink or inks so as to reproduce the image as accurately as possible and produces the appropriate color separations automatically. CR Categories: I.3.4 [Computer Graphics]: Graphics Utilities Additional Keywords: color reproduction, color printing, duotone, gamut mapping, Neugebauer model 1 Introduction Modern color reproduction typically employs a fixed set of processcolor inks: cyan, magenta, yellow, and sometimes black. Placed on top ...

We show how importance-driven refinement and a wavelet basis can be combined to provide an efficient solution to the global illumination problem with glossy and diffuse reflections. Importance is used to focus the computation on the interactions having the greatest impact on the visible solution. Wavelets are used to provide an efficient representation of radiance, importance, and the transport operator. We discuss a number of choices that must be made when constructing a finite element algorithm for glossy global illumination. Our algorithm is based on the standard wavelet decomposition of the transport operator and makes use of a four-dimensional wavelet representation for spatially and angularly varying radiance distributions. We use a final gathering step to improve the visual quality of the solution. Features of our implementation include support for curved surfaces as well as texture-mapped anisotropic emission and reflection functions.