Imaging apparatus inevitably impose undesirable noises onto acquired images during real imaging process. Usually these noises are too faint to cause unpleasing visual effects, however they degrade image fidelity and s...
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ISBN:
(纸本)0819437034
Imaging apparatus inevitably impose undesirable noises onto acquired images during real imaging process. Usually these noises are too faint to cause unpleasing visual effects, however they degrade image fidelity and significantly lower the compression ratio of lossless coding. More baffling, in this case, there leaves little room for traditional noise filtering methods to work. This paper will introduce some of our efforts trying to weaken the effect of such Micro Noise during near-lossless compression. Experimental results on ISO test images and micro Gassian noises demonstrate that with potentiality of filtering micro noise, an improved near-lossless coder (MNF) can not only achieve obviously higher compression ratio but also provide better image fidelity (measured by mean squared error) than lossless coding.
A compression scheme for calibrated images depicting a static scene from arbitrary viewpoints is presented. 3-D scene geometry is reconstructed, and view-dependent texture maps are generated from all images. Texture i...
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ISBN:
(纸本)0819437034
A compression scheme for calibrated images depicting a static scene from arbitrary viewpoints is presented. 3-D scene geometry is reconstructed, and view-dependent texture maps are generated from all images. Texture is wavelet-coded using the SPIHT coding scheme extended to 4-D, exploiting correlations within as well as between texture maps. During decoding, all texture maps are simultaneously and progressively reconstructed. The coder provides 3-D scene geometry and multiple texture maps, enabling the use of graphics hardware to accelerate the rendering process. Three image sets acquired from real-world objects are used to evaluate the model-based coding scheme. Coding efficiency is shown for geometry approximations of different accuracy.
A system for automatic detection of eye movements in medical applications is presented. It is designed to register exactly the dynamic motions of human eyes. In principle, the system runs independently of specific app...
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ISBN:
(纸本)0819437034
A system for automatic detection of eye movements in medical applications is presented. It is designed to register exactly the dynamic motions of human eyes. In principle, the system runs independently of specific applications and may de used for different medical diagnoses. The method for motion analysis is applied to video image sequences of the retina recorded by a scanning laser ophthalmoscope (SLO). A modified block-matching algorithm has been developed for tracking the ocular fundus in the SLO sequences. The imageprocessing strategies implemented provide high reliability of the motion detection which is used to process off-line. Several modifications have been developed in order to take into account the video quality of the SLO sequences. Additionally, some improvements have been implemented to increase the speed of the software. The system includes a phase of automatic motion detection followed by a subsequent phase of manual quality control. In the latter phase, an efficient tool for error detection and correction guarantees high quality and security of movement detection, which is of great importance in clinical applications.
To retrieve efficiently a specific image in their voluminous image database, users need of appropriate tools. That is the reason why, over the last years, content-based image retrieval systems have been developed. In ...
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ISBN:
(纸本)0819437034
To retrieve efficiently a specific image in their voluminous image database, users need of appropriate tools. That is the reason why, over the last years, content-based image retrieval systems have been developed. In these systems, users formulate their queries from both visual and textual descriptions. Consequently, these features must be described in a well-suited representation in order to satisfy the efficiency and relevant retrieval criterion In the sequel, we will only dwell on one of the most important visual features, namely the shape feature. This feature is essential as it corresponds to region of interest in images. As far as the shape is concerned, an interesting representation can not be reached without efficient synergy between image analysis techniques, mathematics, and database technology. In this paper, the development of our theoretical model describing shape representation for content-based retrieval is presented as well. as the numerical results computed for different simulations. These results are used to show the usefulness of the considered Fourier descriptors (first order and second order interpolations). Under MATLAB, a powerful mathematical software, we analyzed and easily validated the proposed method. To conclude, the relation between Moment theory (another interesting shape representation) and Fourier analysis is discussed.
This paper introduces a novel image coding principle: the coding of an image to maximise its interpretability versus bit-rate performance. For large surveillance images it would be more appropriate if the encoded wave...
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ISBN:
(纸本)0819437034
This paper introduces a novel image coding principle: the coding of an image to maximise its interpretability versus bit-rate performance. For large surveillance images it would be more appropriate if the encoded wavelet coefficients were prioritised in their order of importance for interpretability. This paper presents one method for such a system. The importance values are derived from the estimates of the local dimension in image regions, which is a measure on the local image dynamics. The scale of the area used for the estimates is dyadic and maps to the image scale-space. The wavelet coefficients from a Mallat(1) decomposition are prioritised according to their importance, based on the focal information dimension estimates. Subjective evaluations have shown that this importance prioritisation schema is preferred over the traditional progressive PSNR optimal approach. The paper will discuss the implementation of an importance prioritisation schema for the EBCOT2 image coder, which is the algorithm used in JPEG2000.(3) The concept of importance prioritisation for interpretability may benefit future low bit-rate image and video coding.
A camera used in video communication over Internet is usually placed on top of a monitor, therefore it is hard for an user to make a natural eye contact with the peer communicator since the user gazes at the monitor, ...
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ISBN:
(纸本)0819437034
A camera used in video communication over Internet is usually placed on top of a monitor, therefore it is hard for an user to make a natural eye contact with the peer communicator since the user gazes at the monitor, not the camera lens. In this paper, we propose a simple 3D mesh warping technique for gaze-correction. It performs 3D rotation of face image by a certain correction angle to obtain a gaze-corrected image. The correction angle is estimated in an unsupervised way by using invariant face feature, and a very simple face section model is used in 3D rotation instead of precise, but not easily attainable in most cases, 3-D face models. The method is computationally simple enough to implement for real-time casual video communication applications.
This paper tackles the 3D model-based representation of video sequences of real scenes and focuses on sequences derived from a camera moving in static scenes. 3D models can be used advantageously for compression purpo...
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ISBN:
(纸本)0819437034
This paper tackles the 3D model-based representation of video sequences of real scenes and focuses on sequences derived from a camera moving in static scenes. 3D models can be used advantageously for compression purposes. Moreover, they are quite adapted to interactive viewpoint synthesis. The objective is here to build a compact 3D-based representation of a given video sequence. It first requires establishing correspondence between images from which viewpoint parameters and depth maps are estimated. The representation is then built by selecting in the image sequence the data that are necessary and sufficient to reconstruct the sequence at a given quality level. This paper presents this second part of the system. Our representation is a structured view-dependent 3D model composed of an ordered set of rectangular patches describing 2.5D regions (flag+texture+depth for each pixel) with attached viewpoint parameters sets.
On October 1, 1999, the 2nd-generation HDTV prototype system of China has been successfully used for the first experimental live HDTV terrestrial broadcasting in China. Shanghai Jiao Tong University has developed the ...
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ISBN:
(纸本)0819437034
On October 1, 1999, the 2nd-generation HDTV prototype system of China has been successfully used for the first experimental live HDTV terrestrial broadcasting in China. Shanghai Jiao Tong University has developed the HDTV video encoder and the system multiplexer of the system. This paper will focus on the design and implementation of HDTV video encoder. Firstly, the backgrounds of developing HDTV in China are introduced briefly. Secondly, the whole second-generation HDTV prototype system scheme is overviewed. Thirdly, design and implementation of the HDTV video encoder are discussed in detail. Finally, the author discusses the development prospects of HDTV in China.
To generate highly realistic scenes of a virtual studio, we are developing technology of a new virtual studio based on image components from real videos instead of CG. And we carl this system an image-Based Virtual St...
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ISBN:
(纸本)0819437034
To generate highly realistic scenes of a virtual studio, we are developing technology of a new virtual studio based on image components from real videos instead of CG. And we carl this system an image-Based Virtual Studio. Two types of image components are now being developed for the system. These are an environmental image component for long distant view and a three-dimensional image component for short distant view. We have newly developed a principal-point alignment camera head for composing a large number of camera images to a high-resolution omnidirectional image as the environmental image component. We constructed an omnidirectional image (16,000 x 16,000 pixels) from about 1000 camera images, and finally could compose them to the whole view image seamlessly. We also experimentally developed a high-definition image-based virtual studio with these two types of image components. And the system has been confirmed as useful for TV program production.
Concentric mosaics have the ability to quickly capture a complete 3D view of a realistic environment and to enable a user to wander freely in the environment. However, the data amount of the concentric mosaics is huge...
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ISBN:
(纸本)0819437034
Concentric mosaics have the ability to quickly capture a complete 3D view of a realistic environment and to enable a user to wander freely in the environment. However, the data amount of the concentric mosaics is huge. In this paper, we propose an algorithm to compress the concentric mosaic image array through motion compensation and residue coding, which we called reference block codec (RBC). A two-level index table is embedded in the compressed bitstream for random access. During the rendering, the entire compressed concentric mosaic scene is not fully expanded at any time. In stead, only the contents necessary to render the current view are decoded in real time. We denote such rendering scheme as just-in-time (JIT) rendering. Four decoder caches are implemented to speed up the rendering.
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