We present a multi-resolution space carving algorithm that reconstructs a 3D model of visual scene photographed by a calibrated digital camera placed at multiple viewpoints. Our approach employs a level set framework ...
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We present a multi-resolution space carving algorithm that reconstructs a 3D model of visual scene photographed by a calibrated digital camera placed at multiple viewpoints. Our approach employs a level set framework for reconstructing the scene. Unlike most standard space carving approaches, our level set approach produces a smooth reconstruction composed of manifold surfaces. Our method outputs a polygonal model, instead of a collection of voxels. We texturemap the reconstructed geometry using the photographs, and then render the model to produce photo-realistic new views of the scene.
Objective image/video quality measures play important roles in various image/video processing applications, such as compression, communication, printing, analysis, registration, restoration and enhancement. Most propo...
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Objective image/video quality measures play important roles in various image/video processing applications, such as compression, communication, printing, analysis, registration, restoration and enhancement. Most proposed quality assessment approaches in the literature are error sensitivity-based methods. In this paper, we follow a new philosophy in designing image/video quality metrics, which uses structural distortion as an estimation of perceived visual distortion. We develop a new approach for video quality assessment. Experiments on the video quality experts group (VQEG) test data set shows that the new quality measure has higher correlation with subjective quality measurement than the proposed methods in VQEG's Phase I tests for full-reference video quality assessment.
In this paper, we present an adaptive two-pass median filter to remove impulsive noise. In two-pass median filtering, an image contaminated by impulsive noise is processed by a median filter twice. Median filtering is...
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In this paper, we present an adaptive two-pass median filter to remove impulsive noise. In two-pass median filtering, an image contaminated by impulsive noise is processed by a median filter twice. Median filtering is a non-reversible process, i.e., useful information discarded by the filter cannot be recovered. This behavior becomes more apparent in two-pass median filtering. To correct this problem, between the two filtering processes we introduce an adaptive process to selectively replace some pixels by their original values based on the spatial distribution of estimated impulsive noise. Compared with standard median filtering and two-pass median filtering, better results are obtained in terms of visual appreciation and mean squared error. We use examples to demonstrate the performance of the method.
A method of improving the traditional polygonal approximation methods is described. It has properties such as scalability, resilience to noise, controlled levels of approximation and good visual representation. These ...
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A method of improving the traditional polygonal approximation methods is described. It has properties such as scalability, resilience to noise, controlled levels of approximation and good visual representation. These properties are direct result of the use of scale information to derive the vertices positions of the polygonal approximation. The vertices are situated on the contour points where the changes of the contour directions are at their major sharp positions. An encoding method with a scalable polygonal approximation of shapes is defined, which results in a good relation between the distortion and the bit rate.
Region-of-interest coding and unequal error protection are two important tools in video communication systems to improve received visual quality. One common property of the two techniques is that unequal coding or tra...
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Region-of-interest coding and unequal error protection are two important tools in video communication systems to improve received visual quality. One common property of the two techniques is that unequal coding or transmission is applied to improve the quality of the most important parts of images. The proposed sub-picture coding technique facilitates both region-of-interest coding and unequal error protection by partitioning images to regions of interest and separating the corresponding coded data units from each other. Simulation results show that the overall subjective quality is considerably improved compared to the conventional coding schemes.
In this paper, we propose an automatic method for the objective evaluation of segmentation results. The method is based on computing the deviation of the segmentation results from a reference segmentation. The discrep...
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In this paper, we propose an automatic method for the objective evaluation of segmentation results. The method is based on computing the deviation of the segmentation results from a reference segmentation. The discrepancy between two results is weighted based on spatial and temporal contextual information, by taking into account the way humans perceive visual information. The metric is useful for applications where the final judge of the quality is a human observer or the results of segmentation are otherwise processed in a human-like fashion. The proposed evaluation has been applied both to automatically provide a ranking among different segmentation algorithms and to optimally set the parameters of a given algorithm.
The wavelet based SPIHT algorithm has recently attracted significant attentions from researchers in image coding. SPIHT maximizes PSNR (or minimize MSE) for each bit it transmitted, however, it is well known that PSNR...
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The wavelet based SPIHT algorithm has recently attracted significant attentions from researchers in image coding. SPIHT maximizes PSNR (or minimize MSE) for each bit it transmitted, however, it is well known that PSNR is not a good indicator of the perceptual image fidelity. Human visual perception is more sensitive to distortions in lower frequency components than distortions in the higher frequency components. In this paper, we enhance SPIHT by introducing a process called JND_SQ, between wavelet transform and SPIHT. JND_SQ allows SPIHT to maximize perceptual fidelity instead of PSNR for each bit transmitted. We proposed a perceptual fidelity criterion called JND_PSNR based on the SY JND model, the new criterion is more consistent with human perception than PSNR. Experimental results show that JND_SPIHT outperforms SPIHT in terms of JND_PSNR. The JND_SQ process results in a large amount of zeros, which can be further utilized to improve the speed of SPIHT. Finally, JND_SQ can be turned off if the original SPIHT is desired.
This paper presents a novel accelerated predictive-transform (APT) modeling methodology for use in compression. The APT scheme is illustrated with a monochrome 2D image compression application yielding very promising ...
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ISBN:
(纸本)0780374029
This paper presents a novel accelerated predictive-transform (APT) modeling methodology for use in compression. The APT scheme is illustrated with a monochrome 2D image compression application yielding very promising results. For example, when the Lena image is compressed to 0.056 bits per pixel and the pixel blocks are of dimension 16×16, it is shown that both the design and implementation computational complexity of the prior predictive-transform (PT) modeling art is improved by a factor of 12 without any loss in the visual quality of the compressed image. The APT methodology can also be used in other application areas such as estimation;detection, identification, channel and source integrated coding, and control and other related areas.
In the future, digital set-top boxes may serve as the primary access point for wireless home networks, enabling mobile users to use video conferencing as well as streaming applications on hand-held devices. In this sc...
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In the future, digital set-top boxes may serve as the primary access point for wireless home networks, enabling mobile users to use video conferencing as well as streaming applications on hand-held devices. In this scenario, an important issue that must be addressed is the limited energy supply of a mobile device. This is of course a relevant issue for any wireless device. We focus on methods for efficiently utilizing transmission energy in wireless video communications. We present a general framework for the problem of minimizing the transmission energy required to provide an acceptable level of video quality. We discuss two special cases in which communication resources are adjusted simultaneously with the source coding parameters in order to provide (i) packet loss adaptation and (ii) transmission rate adaptation.
In this paper, we present a probabilistic approach to decide whether or not the extracted facial features are appropriate for creating 3D face models. Automatically extracted 2D facial features from a video sequence a...
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In this paper, we present a probabilistic approach to decide whether or not the extracted facial features are appropriate for creating 3D face models. Automatically extracted 2D facial features from a video sequence are fed into the proposed probabilistic framework before a corresponding 3D face model is built to avoid generating unnatural or non-realistic 3D faces. In addition, a new algorithm for audio-to-visual conversion based on the constrained optimization is presented to generate visual parameters for driving the mouth movement of the 3D face models from speech. Lagrangian optimization is applied to transform a constrained problem into an unconstrained problem. Experimental results are provided to show the effectiveness and validity of the proposed algorithms for various video sequences and speech.
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