Images and Image-Based Techniques (IBR)

By Hal Newnan
17 August 2001 Friday, West Hall A

Chair: Brian A. Barsky, University of California, Berkeley

Image-Based Motion Blur for Stop Motion Animation
Gabriel J. Brostow, Irfan Essa, Georgia Institute of Technology
Keywords: Animation, Applications, Computer Vision, Image Processing, Image-Based Rendering, Object Tracking, and Video

Brostow speaks of being able to segment pixels that are moving from one image to the next, blurring these, and leaving the pixels that are not changing unscathed. This is a major improvement over older methods, as seen in the demo video.

A Simple and Efficient Error-Diffusion Algorithm
Victor Ostromoukhov, Universite de Montreal
Keywords: Halftoning and Dithering

Ostromoukhov speaks of "Halftoning" as basic but important, and of the "Floyd-Steinberg E-D" as obsolete. He answers the question "What is halftoning?" with: "a method of producing an illusion (dithering) of smoothness." By audience response Ostromoukhov's offering is the "best of class" for this session.
His solution offers visual quality, excellent speed, conceptual simplicity and legal availability (i.e. all of the criterion needed) in visual quality for low -res displays. The DBS-based Algorithm is still the best for quality but it is slow and complex. Our solution verges on the best quality but is quick, easy, and FREE. All the documentation is available to you for download at http://www.iro.umontreal.ca/~ostrom/.

Simulating Decorative Mosaics
Alejo Hausner, University of Toronto
Keywords: Computational Geometry, Frame Buffer Algorithms, Non-Realistic Rendering, Paint Systems, Scientific Visualization

Hausner says that his topic is pointing in the opposite way from Ostromoukhov's, because he is looking to emphasize the visual artifacts (albeit in a highly organized way). Decorative Mosaics are among the most long-lasting graphics to be found, and usually graphics are disposable items.
Pixels have orientation, and Hausner suggests that they were developed three thousand years ago as tiles, and that edges are visually important in mosaics. His scientific discussion unfurls around the use of Centroidal Voronoi Diagrams (or CVDs). CVDs after convergence appear as a honeycomb shape that is associated with minimum energy arrangements. Key idea 1: CVDs and tilings use best circle packing, and that equals hexagonal tiling. Key idea 2: Why Cones? It is a plot of a distance function for a Manhattan Metric as a square cone (a pyramid).
This is an effective way to make mosaics of any 2D image.

Real-Time Hatching
Emil Praun, Matthew Webb, Adam Finkelstein all of Princeton University
Hugues Hoppe of Microsoft Research
Keywords: Animation Systems, Frame Buffer Algorithms, Nonrealistic Rendering, Texture Mapping, Automatic Indication

This is a way to apply a non-realistic style that will be consistent through multiple frames, and is therefore suitable for use in animation.