image compression based on transform coding appears to be approaching an asymptotic bit rate limit for application-specific distortion levels. However, a new compression technology, called object-based compression (OB...
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ISBN:
(纸本)0819454990
image compression based on transform coding appears to be approaching an asymptotic bit rate limit for application-specific distortion levels. However, a new compression technology, called object-based compression (OBC) promises improved rate-distortion performance at higher compression ratios. OBC involves segmentation of image regions, followed by efficient encoding of each region's content and boundary. Advantages of OBC include efficient representation of commonly occurring textures and shapes in terms of pointers into a compact codebook of region contents and boundary primitives. this facilitates fast decompression via substitution, at the cost of codebook search in the compression step. Segmentation cose and error are significant disadvantages in current OBC implementations. Several innovative techniques have been developed for region segmentation, including (a) moment-based analysis, (b) texture representation in terms of a syntactic grammar, and (c) transform coding approaches such as wavelet based compression used in MPEG-7 or JPEG-2000. Region-based characterization with variance templates is better understood, but lacks the locality of wavelet representations. In practice, tradeoffs are made between representational fidelity, computational cost, and storage requirement. this paper overviews current techniques for automatic region segmentation and representation, especially those that employ wavelet classification and region growing techniques. Implementational discussion focuses on complexity measures and performance metrics such as segmentation error and computational cost.
Recent progress in shape theory, including the development of object/image equations for shape matching and shape space metrics (especially object/image metrics), is now being exploited to develop new algorithms for t...
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ISBN:
(纸本)0819454990
Recent progress in shape theory, including the development of object/image equations for shape matching and shape space metrics (especially object/image metrics), is now being exploited to develop new algorithms for target recognition. this theory makes use of advanced mathematical techniques from algebraic and differential geometry to construct generalized shape spaces for various projection and sensor models, and then uses that construction to find natural metrics that express the distance (difference) between two configurations of object features, two configurations of image features, or an object and an image pair. Such metrics produce the most robust tests for target identification;at least as far as target geometry is concerned. Moreover, they also provide the basis for efficient hashing schemes to do target identification quickly and provide a rigorous foundation for error analysis in ATR.
We present the further development of a watermarking technique that embeds an authentication signal in an image. In this paper, we concentrate on the JPEG 2000 image format. the detection/extraction of this signal can...
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ISBN:
(纸本)0819454990
We present the further development of a watermarking technique that embeds an authentication signal in an image. In this paper, we concentrate on the JPEG 2000 image format. the detection/extraction of this signal can,then be used to decide whether the image has gone through any intentional malicious tampering. therefore, the watermark needs to be fragile to such tampering attacks. On the other hand, we need to make sure that the authentication is robust to change resulting from the watermarking process itself, or from necessary changes such as image compression. We address the robustness against watermarking process issue in two ways. First, we decompose the image into phase and magnitude values. A signature is then generated from the phase values. In particular, binary phase-only filters and their variants will are utilized for this. this signature is subsequently hidden into the magnitude part by a bit-plane embedding technique. the disjoint operations of signature generation and signature embedding minimize the embedding artifacts of the authentication signal. Secondly, we use wavelet decomposition, whereby, the signature can be generated from one subband, and then it can be embedded in other subband(s), or the same subband.
Recently, several watermarking schemes have been proposed that embed a watermark into two halftone images such that the watermark can be extracted by overlaying these halftone images. the watermark images in these sch...
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ISBN:
(纸本)0819454990
Recently, several watermarking schemes have been proposed that embed a watermark into two halftone images such that the watermark can be extracted by overlaying these halftone images. the watermark images in these schemes are binary images and the pixels in the two halftone images are correlated or not depending on whether the corresponding pixels in the watermark is on or off. In these schemes, the watermark is binary and does not contain detailed features. Furthermore, the extracted watermark contains residual patterns from the two images which reduces the fidelity of the extracted watermark image. this paper proposes a watermarking algorithm that addresses these problems. In addition, the proposed scheme admits more general watermark extraction functions and allows embedding of multiple watermark images.
An ongoing problem in remote sensing is that imagery generally consumes considerable amounts of memory and transmittance bandwidth, thus limiting the amount of data acquired. the use of high quality image compression ...
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ISBN:
(纸本)0819454990
An ongoing problem in remote sensing is that imagery generally consumes considerable amounts of memory and transmittance bandwidth, thus limiting the amount of data acquired. the use of high quality image compression algorithms, such as the wavelet-based JPEG2000, has been proposed to reduce much of the memory and bandwidth overhead;however, these compression algorithms are often lossy and the remote sensing community has been wary to implement such algorithms for fear of degradation of the data. We explore this issue for the JPEG2000 compression algorithm applied to Landsat-7 Enhanced thematic Mapper (ETM+) imagery. the work examines the effect that lossy compression can have on the retrieval of the normalized difference vegetation index (NDVI). We have computed the NDVI from JPEG2000 compressed red and NIR Landsat-7 ETM+ images and compared withthe uncompressed values at each pixel. In addition, we examine the effects of compression on the NDVI product itself. We show that boththe spatial distribution of NDVI and the overall NDVI pixel statistics in the image change very little after the images have been compressed then reconstructed over a wide range of bitrates.
Steganography is a technique of embedding information in innocuous data such that only the innocent data is visible. the wavelet transform lends itself to image steganography because it generates a large number of coe...
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ISBN:
(纸本)0819454990
Steganography is a technique of embedding information in innocuous data such that only the innocent data is visible. the wavelet transform lends itself to image steganography because it generates a large number of coefficients representing the information in the image. Altering a small set of these coefficients allows embedding of information (payload) into an image (cover) without noticeably altering the original image. We propose a novel, dual-wavelet steganographic technique, using transforms selected such that the transform of the cover image has low sparsity, while the payload transform has high sparsity. Maximizing the sparsity of the payload transform reduces the amount of information embedded in the cover, and minimizing the sparsity of the cover increases the locations that can be altered without significantly altering the image. Making this system effective on any given image pair requires a metric to indicate the best (maximum sparsity) and worst (minimum sparsity) wavelet transforms to use. this paper develops the first stage of this metric, which can predict, averaged across many wavelet families, which of two images will have a higher sparsity. A prototype implementation of the dual-wavelet system as a proof of concept is also developed.
A bit rate allocation (BRA) strategy is needed to optimally compress three-dimensional (3-D) data on a per-slice basis, treating it as a collection of two-dimensional (2-D) slices/components. this approach is compatib...
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ISBN:
(纸本)0819454990
A bit rate allocation (BRA) strategy is needed to optimally compress three-dimensional (3-D) data on a per-slice basis, treating it as a collection of two-dimensional (2-D) slices/components. this approach is compatible withthe framework of JPEG2000 Part 2 which includes the option of pre-processing the slices with a decorrelation transform in the cross-component direction so that slices of transform coefficients are compressed. In this paper, we illustrate the impact of a recently developed inter-slice rate-distortion optimal bit-rate allocation approach that is applicable to this compression system. the approach exploits the MSE optimality of all JPEG2000 bit streams for all slices when each is produced in the quality progressive mode. Each bit stream can be used to produce a rate-distortion curve (RDC) for each slice that is MSE optimal at each bit rate of interest. the inter-slice allocation approach uses all RDCs for all slices to optimally select an overall optimal set of bit rates for all the slices using a constrained optimization procedure. the optimization is conceptually similar to Post-compression Rate-Distortion optimization that is used within JPEG2000 to optimize bit rates allocated to codeblocks. Results are presented for two types of data sets: a 3-D computed tomography (CT) medical image, and a 3-D metereological data set derived from a particular modeling program. For comparison purposes, compression results are also illustrated for the traditional log-variance approach and for a uniform allocation strategy. the approach is illustrated using two decorrelation tranforms (the Karhunen Loeve transform, and the discrete wavelet transform) for which the inter-slice allocation scheme has the most impact.
the reconstruction of 3D visual data from 2D images is an important task in image processing. For the estimation of depth in the scene, a stereoscopic image pair is necessary. When dealing, withcoding and transmissio...
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ISBN:
(纸本)0889864543
the reconstruction of 3D visual data from 2D images is an important task in image processing. For the estimation of depth in the scene, a stereoscopic image pair is necessary. When dealing, withcoding and transmission of such stereoscopic imagedata, single imagecoding is not suitable here. the disparity, i.e. the local displacements in the image pair, can be used for an efficient coding approach. To ensure good quality, lossless coding is applied and compared. In order to the specific content of the disparity map, compression gains higher than factor 10 are achievable. At the receiver, the stereoscopic image pair can be reconstructed having only one original image and the disparity map. An interlaced image is produced to ensure the persistence of the 3D impression.
In this paper and its sequel, we will examine two fundamental problems related to object recognition for the generalized weak perspective model of image formation. We offer a complete solution to both problems for con...
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ISBN:
(纸本)0819450812
In this paper and its sequel, we will examine two fundamental problems related to object recognition for the generalized weak perspective model of image formation. We offer a complete solution to both problems for configurations of point features. Geometric Constraints (Object/image Equations): the problem of single view recognition is central to many image understanding and computer vision tasks. the results in this paper provide a way to understand the relationship that exists between the 3D geometry and its "residual" in a 2D image. this relationship is completely characterized (for a particular combination of features) by a set of fundamental equations in the 3D and 2D shape coordinates. these equations are know as object/image relations. they can be used to test for the geometric consistency between an object and an image. For example, by fixing point features on a known object, we get constraints on the 2D shape coordinates of possible images of those features. Conversely, if we have specific 2D features in an image, we will get constraints on the 3D shape coordinates of objects capable of producing that image. this yields a test for which object is being viewed. the object/image equations are thus fundamental tools for the identification/recognition problem. In this paper we give the complete solution, and find explicitly, the object/image equations for point features in the generalized weak perspective case. this entails working on spaces known as Grasssmannians and exploiting certain incidence correspondences and the so-called Phicker relations. Vision Metrics: We would like to know if two configurations of a fixed number of points in 2D or 3D are the same if we allow affine transformations. If they are, then we want a distance of zero, and if not, we want a distance that expresses their dissimilarity - always recounizing that we can transform the points. the Procrustes metric, described in the shape theory literature [4], provides such a notion of distance
In recent years technology developments for SAR front-end and for on-board SAR data processing have been performed at Astrium GmbH, Germany. Remarkable progress has been made in the respective demonstrator projects DE...
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In recent years technology developments for SAR front-end and for on-board SAR data processing have been performed at Astrium GmbH, Germany. Remarkable progress has been made in the respective demonstrator projects DESA, EUCLID RTP 9.7, and TOPAS. A summary of the major results and achievements is presented.
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