Bert Deknuydt

A deblocking scheme suitable for use inside the codec loop

In many coding algorithms, one of the most annoying types of image deterioration occurring at lower bit rate is the so called blocking effect. It is caused by the unnatural way of dividing up images in rectangular blocks with a fixed grid. Because the coding of each block is independent, nothing assures the continuity of the coded image values at the border between blocks. This gives rise to sometimes prominent artificial edges in the coded image. In image sequences, a background grid of non-moving edges viewed against a moving scene, results in a very unnatural and unpleasing type of degradation. To prevent these blocking effects from occurring, a lot of algorithms have been used. However, many are not suitable for incorporation in the main codec loop, but can only be seen as a cosmetic post filter. The simple algorithm described here is usable for that purpose.<<ETX>>

Coding of Dynamic Texture on 3D Scenes

As cheap and powerful 3D render engines become commonplace, demand for nearly realistic 3D scenes is increasing. Besides more detailed geometric and texture information, this presupposes the ability to map dynamic textures. This is obviously needed to model movies, computer and TV screens, but also for example the landscape as seen from inside a moving vehicle, or shadow and lighting effects that are not modeled separately. Downloading the complete scene to the user, before letting him interact with the scene, becomes very unpractical and inefficient with huge scenes. If the texture is not a canned sequence, but a stream, it is altogether impossible. Often a back channel is available, which allows on demand downloading so the user can start interacting with the scene immediately. This can save considerable amounts of bandwidth. Specifically for dynamic texture, if we know the viewpoint of the user (or several users), we can code the texture taking into account the viewing conditions, i.e. coding and transmitting each part of the texture with the required resolution only. Applications that would benefit from view-dependent coding of dynamic textures, include (but are not limited to) multiplayer 3D games, walkthroughs of dynamic constructions or scenes and 3D simulations of dynamic systems. In this paper, a scheme based on an adapted OLA (Optimal Level Allocation) video codec is shown. Important data rate reductions can be achieved with it.

Initial segmentation of a scene using the results of a classification based motion estimator

This paper describes a possible strategy to migrate from block-based coding towards object-based coding. We use the results of an intelligent motion estimation algorithm to define low resolution (block based) starting islands. The information from the motion vector field and the image data together with spatial relations are used to measure the cost to belong to a given object. Finally a selection procedure is used to generate the high resolution (pixel based) objects.<<ETX>>