IEEE Transactions on Circuits and Systems for Video Technology

Power consumption is very critical for portable video applications such as portable videophone and digital camcorder. Motion estimation (ME) in the video encoder requires a huge amount of computation, and hence consumes the largest portion of power. We propose a novel method of reducing power consumption of the ME by adaptively changing the pixel resolution during the computation of the motion vec... View full abstract»

We first present new concepts applicable to the design of multimedia search and retrieval schemes in general, and to MPEG-7 in particular, the multimedia description standard in progress. Raw multimedia data is assumed to exist in the form of programs that typically consist of a combination of media types such as visual, audio, and text. We partition each such media stream into smaller units based... View full abstract»

Variable bit-rate (VBR) MPEG video traffic is highly bursty due to group of pictures structure, and shows time-variant statistical characteristics due to scene changes. These characteristics make it more difficult to manage network resources, and leads to the significant reduction in network utilization. We deal with the issues related to efficiently transmitting VBR MPEG video traffic over asynch... View full abstract»

The extensive use of discrete transforms in image and video coding suggests the investigation on filtering before downsampling (FBDS) and filtering after upsampling (FAUS) methods directly acting on the transform domain. We describe the "transform-damain resolution translation" technique that gives flexibility to resize windows of each video conferencing session for a server compositing without ex... View full abstract»

Multipoint videoconference service allows multiple and far-away conferees to conduct a meeting without leaving their offices. Variable-bit-rate video compression is attractive for videoconferencing, because it can provide a constant image quality and it can effectively utilize the communication bandwidth via statistical multiplexing. When some conferences temporarily generate heavy traffic to a li... View full abstract»

This paper presents a shape-adaptive wavelet coding technique for coding arbitrarily shaped still texture. This technique includes shape-adaptive discrete wavelet transforms (SA-DWTs) and extensions of zerotree entropy (ZTE) coding and embedded zerotree wavelet (EZW) coding. Shape-adaptive wavelet coding is needed for efficiently coding arbitrarily shaped visual objects, which is essential for obj... View full abstract»

This paper investigates ways to explore the between frame correlation of shape information within the framework of an operationally rate-distortion (ORD) optimized coder. Contours are approximated both by connected second-order spline segments, each defined by three consecutive control points, and by segments of the motion-compensated reference contours. Consecutive control points are then encoded... View full abstract»

Previous developments in digital video compression, transmission, and displays have made object-based video viable for many applications, e.g., coding chroma-keyed video for digital TV and manipulating video objects on interactive multimedia terminals, etc. To facilitate these applications, there is a demand on international standards for coding methods and transmission formats for object-based na... View full abstract»

The ability to construct intracoded frame from motion-compensated intercoded frames directly in the compressed domain is important for efficient video manipulation and composition. In the context of motion-compensated discrete cosine transform (DCT)-based coding of video as in MPEG video, this problem of DCT-domain inverse motion compensation has been studied and, subsequently, improved faster alg... View full abstract»

A novel video-object segmentation algorithm is proposed, which takes the previously estimated 2-D dense motion vector field as input and uses the generalized recursive shortest spanning tree method to approximate each component of the motion vector field as a piecewise planar function. The algorithm is successful in capturing 3-D planar objects in the scene correctly, with acceptable accuracy at t... View full abstract»

With the popularity of multimedia acceleration instructions such as MMX, MPEG decompression is increasingly executed on general purpose processors instead of dedicated MPEG hardware. The gap between processor speed and memory access means that a significant amount of time is spent in the memory system. As processors get faster-both in terms of higher clock speeds and increased instruction level pa... View full abstract»

Arithmetic coding in H.263 is based on models that assign a fixed probability to each possible value of some syntax element. The effect of adapting the models according to the dynamically changing statistics is analyzed. Simulation results show improvements in all studied cases. View full abstract»

We propose a post-processing method in the wavelet transform domain that can significantly reduce the blocking effects in low-bit-rate block-transform-coded images. Although the quantization noise of the transform coefficients is the sole source of error in a coded image, the properties of block transform make the errors appear in two categories: blocky noise, which causes blocking effects, and gr... View full abstract»

This paper has developed a fast variable-length decoder which uses a plane separation technique to reduce the processing time of the feedback path in the decoder. The developed decoder performs two shift processes and a decision process concurrently. Therefore, the processing time in the feedback path of our developed variable length decoder can be improved and determined by the longest time among... View full abstract»

This paper proposes a polynomial search (PS) algorithm and architecture to solve the motion estimation problem in video coding. Simulation results show that the proposed method is not only flexible, but also requires fewer computations to achieve the same mean absolute error results (for QCIF and sub-QCIF video) compared with the existing fast-search algorithms. Finally, a VLSI architecture is als... View full abstract»

Although it is established that the distribution of the discrete cosine transform coefficients can be modeled, it is not known how this knowledge can best be applied to improve the JPEG compression algorithms. We studied this problem by making modifications to both the JPEG baseline encoder and decoder separately. Experimental results show that modifications to the decoder alone do not reduce any ... View full abstract»

We present a multiresolution approach for video indexing and feature matching of subband-coded video databases. Four different scene-change detectors were tested; scene-change detection is applied only on the lowest subband for computational efficiency. Two kinds of scene changes, abrupt and smoothly accumulated, mark the beginning of new scene segments. The index for each scene segment is the pai... View full abstract»