MIME-Version: 1.0 Server: CERN/3.0 Date: Sunday, 01-Dec-96 19:46:18 GMT Content-Type: text/html Content-Length: 3971 Last-Modified: Saturday, 10-Aug-96 00:52:08 GMT Image and Video Transition FX for Rivl

Image and Video Transition FX for Rivl

Jose-Luis Fernandez, Valerie J. Ohm and Amith Yamasani

16 October 1995


1. Overview

Rivl is a language extension to Tcl/Tk for manipulating images and video sequences. It comes with a set of primitives such as fade, rotate, overlay, etc. The purpose of this project is to extend the set of primitives and use them for creating complex transitional effects between two images or video sequences.

2. Deliverables

  1. A set of primitives to create transitional effects between two images or on one image by creating a sequence of intermediate images. Effects would include Flip, Deform, Squish, Peel, Fold-up, Melt, Bounce-squish, Morph(?).

  2. The same transitional effects on video sequences.

3. Milestones

4. Technical Overview

The effects

Flip: This is basically a shearing operation with a fixed line on either of the two axes. The parameters would be the position and orientation of the fulcrum, the image, and the angle through which to flip the image. In the case of flipping video, the frames would be processed one by one with the angle increasing gradually.

Melt: The image seems to melt into a liquid and flow down out of sight. This would involve generating a random smooth wave and shearing the image with the wave. The wave would also have to change in shape gradually so that it doesn't look like a curtain falling.

Fold-up: This effect simulates the folding up of a piece of paper over and over again. How the image is to be folded can be determined by parameters to the function. The image can be folded as an opaque piece of paper or as a transparent one.

Peel: This is a real cool effect - like peeling off a sheet of paper placed over another one. Even a video sequence can be "peeled" off to expose another sequence. The direction of peeling can be specified as a parameter. This effect could be extended to rolling it away like a scroll.

Squish: Squishing an image would cause it to get compressed with a bulge in the middle. Bounce-squish is a variant of this where the squishing is a little springy. This involves shearing the image unevenly, applying a sine function to the shear and gradually increasing the amplitude of the sine wave.

Deform: Deforming an image would involve squeezing a rectangular image into a nonrectangular area which could be a quadrilateral or an oval. First the image would be resized in both dimensions to fit the bounding rectangle of the destination shape and then it would be sheared to fit the actual shape.

In most of these effects, as one video sequence gets transformed, the next sequence fills the background.