K. Fazekas

Full scheme of MPEG4-like codec based on wavelet transform

We propose a full scheme of video codec with enhanced features, which are very useful for multimedia applications. Our codec supports video object based compression: the encoder automatically detects and tracks moving video objects with minor human interactivity. Each object is represented in constrained Delaunay mesh structure and encoded in motion-compensation manner to reduce the needed bit-rate for transmission. By transforming the residual errors (used as correction-values after motion-estimation) into wavelet domain followed by quantising phase, we not only reduce the bandwidth to even lower limit but also guarantee the proper quality (up to the possibly maximum deployed level) for various end-users with a bitstream possessing a famous property - the scalability - regardless the speed of the user-access to the communication network. Simulation is also implemented to demonstrate these virtues.

The presentation of three-dimensional objects with single image stereogram

A number of techniques offer us, at last, the possibility of viewing nature - the world of three dimensions - in a more realistic way with the deployment of three-dimensional display systems. Among these various methods, we chose the one based on the single image stereogram algorithm as the target of this paper, with respect to its simplicity, but efficiency in representing the vivid depth information of the real world. The goal of the paper is the improvement of the conventional implementation with our fixed-eyes-based calculation of constraints and with a new way to detect hidden surfaces in a three-dimensional scene. Going further than that, the paper extends the algorithm to moving objects, which is a new aspect, and, therefore, it has not yet been researched well. We also discuss the depth perception obtained by the algorithm and its visibility, a key question for the usability of the images of this category.

Mesh-based error-scalable video object codec for variable bandwidth multimedia communications

The work introduces a complete chain of video object compression. The process is based on an automatic extraction of video objects from raw video. The recent MPEG-4 standard philosophy, including mesh models and wavelet-based compression are involved in the scheme. Constrained Delaunay meshes are used to represent articulated video objects in a flexible manner conveying shape and motion information. The wavelet transform is applied to residual errors for scalable and efficient compression. Results on MPEG-4 test sequences for very low bitrate video communications are encouraging.

Character localization in video sequences

Character localization in video sequences is considered a complex and diverse problem. This task can be decomposed into two clearly separate problems: localizing the character regions in the source image, and recognizing characters within the regions found. This paper presents a character localization strategy that significantly reduces the computing requirement of this task. First we present the edge detection algorithms considered. Then the results are used to create a histogram of the source image that helps localize character coordinates within the image. Finally, erroneously found regions are discarded using three rapid and effective solutions, featuring very high reliability of the proposed methods.

Multimedia courseware: applied photonics

The proposed paper presents development work related to create distance education courseware: applied photonics. In order to minimize the cost at the end-user domain, simple WWW browser with fundamental plug-in (Java applets, HTML pages and LabWindows applets) to support the remote control and video transmission functionality of the system is proposed. The proposed system was tested with remote teaching of MSc and PhD students

Implementation of MPEG4-based transmission in DVB-T technology

Implemented in the 1990s, the MPEG-2 standard as one of todays most widely used image compressing methods provides the basis for baseband data transmission in DVB technology. However, the requirements of the current multimedia applications exceed the capabilities of MPEG-2 systems. On the other hand, these requirements are the driving forces of the MPEG-4 related developments worldwide. Our aim is to contribute to these activities by elaborating procedures that are more effective than the image compressing methods used in MPEG-2 systems, as well as by integrating them into DVB systems

Content-based mesh generation algorithm

The work presents an alternative method for encoding shape-information of video objects, which is a new requirement in the recent evolution of video codec scheme: compressing and transmitting object-based video streams. The proposed method takes the advantage of the latest development in video encoding - motion compensation on the base of mesh presentation of frame -to complete its target. The content-based mesh is deployed to represent video objects, which are detected by a previous video object detector (in a consistent case of scene, detection can simply be a segmenting phase of video frame) or from the whole frame. This special mesh structure constructs the base for successive motion compensation based on mesh-vertices. With content-based mesh, shape information of objects is represented by polygons, therefore it is lossy. Increasing the number of boundary vertices at the cost of bandwidth can alleviate the problem. Integrating the proposed method into a full VOP codec scheme is our perspective.

DEPLOYMENT OF CONSTRAINED DELAUNAY MESH IN VOP SHAPE CODING

The work presents an alternative method for encoding shape-information of video objects, which is a new requirement in the recent revolution of video codec scheme: compressing and transmitting object-based video streams. The proposed method takes the advantage of the latest development in the video encoding – motion compensation on the base of mesh presentation of frame – to complete its target. The so-called constrained Delaunay mesh is deployed to represent video objects, which are detected from a previous video object detector (in a consistent case of scene, detector can simply function like a segmenting phase of video frame). This special mesh structure in one hand constructs the base for successive motion compensation taking root on mesh-vertices. In another hand, the virtue of constrained property opens a possibility to encode the shape of video object implicitly, therefore it reduces the amount of transmitted information. With constrained Delaunay mesh, shape information of objects is presented with polygon, therefore lossy. The problem can be alleviated by increasing the number of boundary vertices at the cost of bandwidth. The work also puts a stress on controlling this trade-off. Results of integrating the proposed method into a full VOP codec scheme are encouraging.