We present a novel error concealment algorithm for block-based video transmission over error-prone networks. We develop a spatial error concealment technique, which combines edge-preserving interpolation and texture a...
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ISBN:
(纸本)0780377133
We present a novel error concealment algorithm for block-based video transmission over error-prone networks. We develop a spatial error concealment technique, which combines edge-preserving interpolation and texture analysis and synthesis, providing a reconstruction of lost macroblocks optimized for visual perception. In particular, the algorithm recovers image edges by coarse-to-fine MAP estimation with a Markov random field prior, and replenishes lost textured areas with a texture synthesized from neighboring macroblocks. Experimental results show that texture synthesis allows achieving improved visual quality of the reconstructed area with respect to other state-of-the-art spatial concealment techniques.
The indexing and retrieval of images in a multimedia database can be a very time consuming process, considering the amount of visual data stored in digital video libraries (DVLs). This paper proposes a semiautomated m...
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ISBN:
(纸本)0780374029
The indexing and retrieval of images in a multimedia database can be a very time consuming process, considering the amount of visual data stored in digital video libraries (DVLs). This paper proposes a semiautomated method to categorize images into groups as a pre-processing step in order to enable faster retrieval from a DVL. The wavelet transform is used to extract low-level features such as colour, texture and shape from images. The extracted features are employed to categorize the images using a novel neural network, the self-organizing tree map. The classification results are then used to train a feed forward neural network to identify the image classes an incoming query image belongs to. Initial experiments show promising results.
The widespread adoption of digital video techniques has generated a requirement for authenticity verification in applications such as criminal evidence, insurance claims and commercial databases. This work addresses p...
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The widespread adoption of digital video techniques has generated a requirement for authenticity verification in applications such as criminal evidence, insurance claims and commercial databases. This work addresses problems that arise from a spatial digital watermarking technique developed to detect frame reordering and dropping scenarios. It discusses the differences between mutual frame types at different bit-rates. Many papers consider detection after MPEG-2 decoding as a naïve approach. However, this approach does offer significant advantages for a slight increase of computation load. This paper also establishes a link between the detector performance and the sequence content. The uniqueness of this work is the comparison of the test results using 18 different standard MPEG test-sequences. The functionality of the algorithm is demonstrated with a simulated attack.
Speech not only conveys the linguistic information, but also characterizes the talker's identity and therefore can be used in personal authentication. While most of the speech information is contained in the acous...
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Speech not only conveys the linguistic information, but also characterizes the talker's identity and therefore can be used in personal authentication. While most of the speech information is contained in the acoustic channel, the lip movement during speech production also provides useful information. In this paper we investigate the effectiveness of visual speech features in a speaker veri£cation task. We £rst present the visual front-end of the automatic speechreading system. We then develop a recognition engine to train and recognize sequences of visual parameters. The experimental results based on the XM2VTS database [I] demonstrate that visual information is highly effective in reducing both false acceptance and false rejection rates in speaker veri£cation tasks.
For inverse filtering methods of blind image restoration, great emphasis has been put into considering the global features of images. Local space statistics of the observed image are estimated recursively and integrat...
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ISBN:
(纸本)0780374886
For inverse filtering methods of blind image restoration, great emphasis has been put into considering the global features of images. Local space statistics of the observed image are estimated recursively and integrated to approach those of the original image. These estimated statistics are refined iteratively and gradually converge to the true values. Combined with the technique of nonnegativity and support constraints recursive inverse filtering (NAS-RIF), an improved recursive inverse filtering algorithm is proposed. Simulations show that the new regularized method behaves better in respect of computational stability, noise resistance, and edge preservation ability.
Objective quality measures or measures of comparison are of great importance in the field of imageprocessing. These measures can be useful for the evaluation and comparison of different algorithms; designed to solve ...
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Objective quality measures or measures of comparison are of great importance in the field of imageprocessing. These measures can be useful for the evaluation and comparison of different algorithms; designed to solve a particular problem. For example, one of the possible applications is the comparison of different filters for image noise reduction. It is well-known that classical quality measures, such as the MSE (mean square error) or the PSNR (peak signal to noise ratio), do not always correspond to visual observations. Therefore, several researchers are - and have been - looking for new quality measures, better adapted to human perception. The existing similarity measures are all pixel-based, and have therefore not always satisfactory results. To cope with this drawback, we propose a similarity measure based on a neighbourhood, so that the relevant structures of the images are observed very well. The new similarity measure is designed especially for use in imageprocessing.
We have analyzed the properties of the HSV (hue, saturation and value) color space with emphasis on the visual perception of the variation in hue, saturation and intensity values of an image pixel. We extract pixel fe...
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We have analyzed the properties of the HSV (hue, saturation and value) color space with emphasis on the visual perception of the variation in hue, saturation and intensity values of an image pixel. We extract pixel features by either choosing the hue or the intensity as the dominant property based on the saturation value of a pixel. The feature extraction method has been applied for both image segmentation as well as histogram generation applications - two distinct approaches to content based image retrieval (CBIR). Segmentation using this method shows better identification of objects in an image. The histogram retains a uniform color transition that enables us to do a window-based smoothing during retrieval. The results have been compared with those generated using the RGB color space.
Combat developers and aviation program managers require knowledge of helmet-mounted display (HMD) performance under operational conditions in order to determine HMD luminance and contrast requirements. In order to eas...
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ISBN:
(纸本)0819444618
Combat developers and aviation program managers require knowledge of helmet-mounted display (HMD) performance under operational conditions in order to determine HMD luminance and contrast requirements. In order to ease this problem, we developed a computer model that predicts available gay-shades based on hardware, ambient light condition, and HMD properties. Included in the model are windscreens, visors, laser protection devices, and properties of developed and fielded HMDs. A graphical user interface and user variables specification allow the developer/manager to model HMDs in specific aircraft. Included with the model is a color model that predicts see-through color imagery. The model produces a visualization of see-through imagery superimposed with HMD symbology based upon model predictions. This allows the user to view simulated imagery as though he were wearing the HMD.
Adaptive processing of structured data using a supervised learning scheme has been successfully applied to many domains, e.g., molecular biology, image classification and retrieval. A self organizing map (SOM) type al...
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Adaptive processing of structured data using a supervised learning scheme has been successfully applied to many domains, e.g., molecular biology, image classification and retrieval. A self organizing map (SOM) type algorithm for processing of structured data using an unsupervised learning approach has previously been proposed. We present an approach using quadtree representation to extract an image structure, and the application of such a structured SOM to image classification problems. Encouraging results achieved by using only six simple visual features show that the structured SOM works well for structural information.
Lossy multimedia transmissions need efficient channel coding schemes. We propose here a specific classification of JPEG2000 data for progressive quality image transmission. We deduce that hierarchical channel coding s...
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Lossy multimedia transmissions need efficient channel coding schemes. We propose here a specific classification of JPEG2000 data for progressive quality image transmission. We deduce that hierarchical channel coding schemes providing Unequal Error Protection (UEP) can be used. In particular, we focus on the use of RCPC codes.
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