18778381
Block truncation coding with adaptive decimation and interpolation
A modification of block truncation coding (BTC) is proposed in this paper. The modification is with a novel adaptive decimation and interpolation method, and predictive entropy coding of the quantization data. The decimation algorithm is designed based on the directional gradients of image blocks so as (1) to preserve the edge information, (2) to enable the interpolator utilize the already reconstructed data in decoder and (3) to better predict the mean value of a block. The quantization data is not directly coded by the two reconstruction levels, but by the block mean and the difference between the block mean and the lower reconstruction level, to further reduce the bit-rate. Compared to other interpolative methods, the new decimation and interpolation method substantially improves the image quality and removes the annoying blocky artifact at the same time. The proposed scheme, which has low computational complexity, is shown to have comparable or better performance to/than BTC methods combined with vector quantization/discrete cosine transform and the most recently BTC modification that utilize the inter-block correlation.
14856574
Error Resilient Video Coding Using Unequally Protected Key Pictures
This paper proposes the use of unequally protected key pictures to prevent temporal error propagation in error-prone video communications. The key picture may either be an intra-coded picture or a picture using a long-term motion compensation reference picture through reference picture selection. The inter-coded key picture uses previous key pictures as motion compensation reference. Key pictures are better protected than other pictures using forward error correction in either source or transport coding. Simulation results show significantly improved error resiliency performance of the proposed technique compared to conventional methods.
15352869
Error Resilient Video Coding using Redundant Pictures
Coding of redundant pictures is supported in the latest international video coding standard H.264 (also known as MPEG-4 part 10 or AVC). This paper proposes a standard-compliant way to encode and decode redundant pictures for improved error resilience. The method is based on a combination of picture-level reference picture selection, reference picture list ordering, and a hierarchical allocation of redundant pictures, which can efficiently prevent temporal error propagation without relying on feedback information. Simulation results show that the method outperforms the optimal loss-aware rate-distortion optimized intra refresh method. The proposed algorithm has been adopted into the H.264 joint model.
14708720
Coding of faded scene transitions
Coding of a scene transition is often a challenging problem, from the compression efficiency point of view, because motion compensation may not be a powerful enough method to represent changes between pictures in the transition. This paper proposes a overlay coding technique for coding faded scene transitions. As shown by extensive simulations, over 50% bit-rate savings in both cross-fades and through-black fades compared to earlier techniques can be achieved. Overlay coding suits situations where video is edited manually or automatically.
14888347
Error Resilient Mode Decision in Scalable Video Coding
Error resilient macroblock mode decision has been extensively investigated in the literature for single-layer video coding, for which error resilient mode decision is also called as intra refresh. In this paper, we present a loss-aware rate-distortion optimized macroblock mode decision algorithm for scalable video coding, wherein more macroblock coding modes than intra and inter are involved. Thanks to the good performance, the proposed method has been adopted into the joint scalable video model by the joint video team.
2496902
Improved Error Concealment Using Scene Information
Signaling of scene information in coded bitstreams was proposed by the authors and adopted into the emerging video coding standard H.264 (also known as MPEG-4 part 10 or AVC) as a supplemental enhancement information (SEI) message. This paper proposes some improved error concealment methods for intra coded pictures and scene transition pictures using the signaled scene information. Simulation results show that the proposed methods outperform conventional techniques significantly.
3124135
Perfectly Secure Message Transmission Revisited
Secure communications guaranteeing reliability and privacy (without unproven assumptions) in networks with active adversaries has been an important research issue. It has been studied for point to point networks by Dolev-Dwork-Waarts-Yung (J. ACM 1993), Desmedt-Wang (Eurocrypt 2002), and Srinathan-Narayanan-Rangan (Crypto 2004). Dolev-Dwork-Waarts-Yung gave necessary and sufficient conditions for secure communication in networks with the condition that (1) all the channels are two-way; or (2) all the channels are one-way from the sender to the receiver. In this paper, we study the general case with a network modeled by a directed graph. In this general case, there are communication channels from the sender to the receiver and there are feedback channels from the receiver to the sender. We give necessary and sufficient bounds on the number of channels that are required from sender to receiver given a number of ldquofeedbackrdquo channels from receiver to sender. We give these bounds for the case reliability is perfect, as well as for the case it is not perfect.
1746465
Pyramidal search of maximum coherence direction for biomedical image interpolation
A multiresolution technique for biomedical image interpolation is presented. It is an extension of the work on directional coherence interpolation (DCI) - a novel gray-level image interpolation method that interpolates the missing image data along the smoothed maximum coherence directions (MCDs). We propose to apply a pyramidal search strategy for MCD estimation. This coarse-to-fine scheme requires less computation time by starting with the reduced amount of data and propagating searching results to finer resolutions. In addition, it also improves robustness compared with our previous single resolution DCI.
6558099
A Generative Method for Textured Motion: Analysis and Synthesis
Natural scenes contain rich stochastic motion patterns which are characterized by the movement of a large number of small elements, such as falling snow, raining, flying birds, firework and waterfall. In this paper, we call these motion patterns textured motion and present a generative method that combines statistical models and algorithms from both texture and motion analysis. The generative method includes the following three aspects. 1). Photometrically, an image is represented as a superposition of linear bases in atomic decomposition using an overcomplete dictionary, such as Gabor or Laplacian. Such base representation is known to be generic for natural images, and it is low dimensional as the number of bases is often 100 times smaller than the number of pixels. 2). Geometrically, each moving element (called moveton), such as the individual snowflake and bird, is represented by a deformable template which is a group of several spatially adjacent bases. Such templates are learned through clustering. 3). Dynamically, the movetons are tracked through the image sequence by a stochastic algorithm maximizing a posterior probability. A classic second order Markov chain model is adopted for the motion dynamics. The sources and sinks of the movetons are modeled by birth and death maps. We adopt an EM-like stochastic gradient algorithm for inference of the hidden variables: bases, movetons, birth/death maps, parameters of the dynamics. The learned models are also verified through synthesizing random textured motion sequences which bear similar visual appearance with the observed sequences.
18961244
Flexible interface matching for Web-service discovery
The Web-services stack of standards is designed to support the reuse and interoperation of software components on the Web. A critical step, to that end, is service discovery, i.e., the identification of existing Web services that can potentially be used in the context of a new Web application. UDDI, the standard API for publishing Web-services specifications, provides a simple browsing-by-business-category mechanism for developers to review and select published services. In our work, we have developed a flexible service discovery method, for identifying potentially useful services and assessing their relevance to the task at hand. Given a textual description of the desired service, a traditional information-retrieval method is used to identify the most similar service description files, and to order them according to their similarity. Next, given this set of likely candidates and a (potentially partial) specification of the desired service behavior, a structure-matching step further refines and assesses the quality of the candidate service set. In this paper, we describe and experimentally evaluate our Web-service discovery process.
32026454
Color-texture image segmentation by integrating directional operators into JSEG method
We presented a new color-texture image segmentation method that combined directional operators and the JSEG (J measure based SEGmentation) algorithm. In particular, two major contributions were set forth in this paper. (1) The two measures defined in JSEG and HSEG (H measure based SEGmentation) were discussed respectively and then we found the over-segmentation problem of JSEG could be attributed partly to the absence of color discontinuity in the J measure. Moreover, we have also proven in essence the H measure is isotropic operators for edge detection in images. (2) A new measure was proposed by integrating directional operators into the J measure, on which our segmentation method was based. The new segmentation method took account of both textural homogeneity and color discontinuity in local regions. Performance improvement due to the proposed modification was demonstrated on a variety of real color images.