IEEE Transactions on Circuits and Systems for Video Technology

Active contours or snakes are an effective edge-based method in segmenting an object of interest. However, the segmented boundary of a moving object in one video frame may lie far from the same moving object in the next frame due to its rapid motion, causing the snake to converge on the wrong edges. To guide the snake toward the appropriate edges, we have added gradient directional information to ... View full abstract»

The impact of a regularization of motion vectors (MVs) on the performance of a block-DCT based video coder (H.263) is addressed. Postprocessing is accomplished by exploiting both the spatial correlation of the vector field and the confidence of the estimated block vectors. A previously proposed adaptive scheme for MV smoothing, based on the theory of vector median filters, is adjusted and embedded... View full abstract»

A systolic motion estimation processor (MEP) core architecture implementing the full-search block-matching (FSBM) algorithm is presented. A unique feature of this MEP architecture is its support of frame-level pipelined operation. As such, it is possible to process pixels from consecutive frames without any processor idle time. It is designed so that no data broadcasting operations are required, a... View full abstract»

Image authentication verifies the originality of an image by detecting malicious manipulations. Its goal is different from that of image watermarking, which embeds into the image a signature surviving most manipulations. Most existing methods for image authentication treat all types of manipulation equally (i.e., as unacceptable). However, some practical applications demand techniques that can dis... View full abstract»

In MPEG, the input pictures can be coded in three different types: I, P, and B. The three pictures require quite different numbers of bits because of different natures of their temporal processing. Hence, an intelligent bit-allocation strategy should assign a picture the number of bits according to the picture's type, as well as the picture organization. This implies a requirement of a prior knowl... View full abstract»

An efficient fractal image-coding method that exploits the correlation between range blocks is proposed. Four domain blocks mapped by the precious neighboring range blocks are considered as the good candidate blocks of the input range block. Experimental results show that when the proposed method is implemented with a fast fractal coding algorithm, it can further reduce the encoding time and bit r... View full abstract»

A fast full-search block-matching algorithm is developed. The matching criterion is the sum of absolute differences or the mean-square error. The algorithm evaluates lower bounds for the matching criteria for subdivided blocks in order to reduce the number of search positions. It also uses the lower bounds for a fast calculation of the matching criterion for the remaining search positions. The com... View full abstract»

This paper presents a new traffic model for MPEG-encoded video sequences. The hybrid gamma/Pareto distribution is used for all three types of frames in MPEG-encoded video sequences, and the present model takes scene changes into account. The autocorrelation structure is modeled using two second-order auto-regressive (AR) processes nested with each other. One AR process is used to generate the mean... View full abstract»

Multimedia processor-based implementations of digital image processing algorithms have become important since several multimedia processors are now available and can replace special-purpose hardware-based systems because of their flexibility. Multimedia processors increase throughput by processing multiple pixels simultaneously using a subword-parallel arithmetic and logic unit architecture. The e... View full abstract»

This paper presents a new technique for region-oriented video compression based on the minimization of a minimum description length (MDL) criterion. The proposed scheme is based on a region-based motion compensation approach, in which the displaced frame difference (DFD) is coded together with the segmentation map and the motion parameters. The region-based segmentation is approximated by a polygo... View full abstract»

Motion search is by far the most complex operation to be performed in a video encoder. This paper proposes a novel fast matching algorithm to help speed up the computation of the matching (distance) metric used in the search, e.g., the sum of absolute difference (SAD). Based on a partial distance technique, our algorithm reduces complexity by terminating the SAD calculation early once it becomes c... View full abstract»

In streaming video applications, video sequences are encoded off-line and stored in a server. Users may access the server over a constant bit rate channel. Examples of the streaming video applications are video-on-demand, archived video news, and noninteractive distance learning. Before the playback, part of the video bitstream is pre-loaded in the decoder buffer to ensure that every frame can be ... View full abstract»

The algorithm and architecture of a variable length code (VLC) codec system using a new group-based approach and achieving full table programmability are presented. According to the proposed codeword grouping and symbol memory mapping, both group searching and encoding/decoding procedures are completed by applying numerical properties and arithmetic operations to codewords and symbol addresses. By... View full abstract»