Implemented in the 1990s, the MPEG-2 standard as one of today's most w i d e b used image compressing methods provides the basis for baseband data transmission in D VB technology. However, the requirements of the cuwenf multimedia applications exceed fhe 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 b-v elaborating procedures that are more effective than the image compressing methods used in MPEG-2 systems, as well as by integrating them into DYB systems. Keywords-MPEG4, DVB-T, MPEGZ-TS, BIFS, wavelet transform 1. DEVELOPMENT Our development activities covered the following major areas: Design and implementation of the internal interfaces of DVB signal transmission subsystems Interfacing the DVB-T baseband channel for MPEG-4 stream transmission and system integration MPEG 4 codec R&D MPEG4 RELATED RESEARCH AND CODEC DEVELOPMENTThe MPEG-4 codec developed by our group and uniquely optimized in some of its properties applies the so-called wavelet transform instead of blockbased compression used in MPEG-2 systems. Wavelet transform is currently one of the most effective methods in image processing. Its advantage to the conventional algorithms (e.g. DCT) is that it simultaneously handles the spatial and frequency domain behavior of the signal. More to the point, it also fits well to the properties of the human vision system (HVS), i.e. the information relevant for the human eye can be extracted by this method and the less important ones can be suppressed. Besides of all the above mentioned, wavelet transform requires less computational timeiresources than the accelerated algorithms of the conventional procedures, what is highly important in image processing: signals cannot be handled in real-time by complicated algorithms, due to the huge amount of information to be processed.The properties of the coefficients resulted by wavelet transform [ l , 2, 31 are severely affected by the base functions of the transform. In the recent decades, several research activities aimed to develop optimal base functions for different applications (Daubechies, Hair, Coiflet, UCLA, etc), We used Daubechies 7/9 filters for transforming the first intra frames, because this provided the best quality and also the P E G 2000 standard uses this base for coding still pictures. The Daubechies 9/3 base was used for coding the differential images, which is also applied by MPEG-4 for coding moving pictures. We used symmetrical extension during the transform, avoiding this way the false edges that would have been resulted by periodic extensions at the picture boundaries. The transform has separately been completed for all the three components (Y, U, V) in case of color pictures. Naturally the size of the U and V components is half of that of the luminance signal in both horizontal and vertical direction.The coefficients resulted by the wavelet transform are quantized and collected. The three components are handled ...
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.
The work presents an altemative 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.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.