IEEE Transactions on Circuits and Systems for Video Technology

This paper analyzes the statistical characters of rate-distortion performances of the fast motion estimation (ME) algorithms in H.264/AVC and introduces an additional early termination scheme with adaptive thresholds for UMHS and CBFPS. This keeps the R-D performance of the original UMHS and CBFPS, while reducing the computational complexity of encoding process considerably. Simulation results in ... View full abstract»

A highly desirable feature in storage video applications is uniform quality. Variable bit rate (VBR) coding has the potential to produce nearly constant quality throughout an entire movie. This can be defined as a bit allocation problem with a long-term constraint on distortion variation. We consider the optimal bit allocation with multiple constraints including disk capacity and the distortion bo... View full abstract»

Nearly all block-based transform schemes for image and video coding developed so far choose the 2-D discrete cosine transform (DCT) of a square block shape. With almost no exception, this conventional DCT is implemented separately through two 1-D transforms, one along the vertical direction and another along the horizontal direction. In this paper, we develop a new block-based DCT framework in whi... View full abstract»

Implementing MPEG-2 to H.264 transcoding schemes in the pixel domain introduces a high degree of computational complexity. In the transform domain, this transcoding is more computationally efficient, and several methods have been developed to address that approach. However, incompatibilities between the two standards, such as the mismatches between the MPEG-2 and H.264 motion compensation processe... View full abstract»

Imperceptibility requirement in video watermarking is more challenging compared with its image counterpart due to the additional dimension existing in video. The embedding system should not only yield spatially invisible watermarks for each frame of the video, but it should also take the temporal dimension into account in order to avoid any flicker distortion between frames. While some of the meth... View full abstract»

Recently, a new image scrambling (i.e., encryption) scheme without bandwidth expansion was proposed based on two-dimensional discrete prolate spheroidal sequences. A comprehensive cryptanalysis is given here on this image scrambling scheme, showing that it is not sufficiently secure against various cryptographical attacks including ciphertext-only attack, known/chosen-plaintext attack, and chosen-... View full abstract»

In this paper, model-based approaches for real-time 3-D soccer ball tracking are proposed, using image sequences from multiple fixed cameras as input. The main challenges include filtering false alarms, tracking through missing observations, and estimating 3-D positions from single or multiple cameras. The key innovations are: 1. incorporating motion cues and temporal hysteresis thresholding in ba... View full abstract»

This paper describes the design and VLSI implementation of a highly efficient, single-port SRAM-based deblocking filter. It can achieve 204 cycles/macroblock throughput for H.264/AVC real-time decoding. Several deblocking filter designs in the literature have been compared and the possibility of realizing them in a pipeline is studied. Eventually we came up with a completely new design which has a... View full abstract»

This paper presents efficient VLSI architectures of the shape-adaptive discrete cosine transform (SA-DCT) and its inverse transform (SA-IDCT) for MPEG-4. Two of the challenges encountered during the exploitation of more efficient architectures for the SA-DCT and SA-IDCT are addressed. One challenge is to handle the architectural irregularity due to the shape-adaptive nature. The other one is to pr... View full abstract»

Congestion control of a variable bit-rate video stream crossing the Internet is crucial to ensuring the quality of the received video. When a fuzzy-logic congestion controller (FLC) changes the sending rate of a video transcoder, it does so without feedback of packet loss, using packet dispersion instead. Compared with the well-known TFRC and RAP controllers, the FLC's sending rate is significantl... View full abstract»

The existing methods to perform motion compensation (MC) in discrete cosine transform (DCT) treat each 8 times 8 block as a fundamental unit and, therefore, involve the high cost of reconstructing prediction frames, especially when the half-pixel motion vectors (MVs) are involved. The proposed method operates on a block of variable size 16 N_y times 16 N<sub>x</sub&g... View full abstract»

This paper proposes a simple yet effective mechanism to select proper reference frames for H.264 motion estimation. Unlike traditional video codecs, H.264 permits more than one reference frame for increased precision in motion estimation. However, motion estimation is complicated by variable block-size motion estimation, which requires significant encoding complexity to identify the best inter-cod... View full abstract»

Many existing techniques for image restoration can be expressed in terms of minimizing a particular cost function. Iterative regularization methods are a novel variation on this theme where the cost function is not fixed, but rather refined iteratively at each step. This provides an unprecedented degree of control over the tradeoff between the bias and variance of the image estimate, which can res... View full abstract»

An effective video copy detection framework should be robust against spatial and temporal variations, e.g., changes in brightness and speed. To this end, a content-based approach for video copy detection is proposed. We define the problem as a partial matching problem in a probabilistic model and transform it into a shortest-path problem in a matching graph. To reduce the computation costs of the ... View full abstract»

Estimation of the facial pose in video sequences is one of the major issues in many vision systems such as face-based biometrics, scene understanding for humans, and others. The proposed method uses a novel pose estimation algorithm based on mutual information to extract any required facial poses from video sequences. The method extracts the poses automatically and classifies them according to vie... View full abstract»