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Detecting Salient BlobLike Image Structures with a ScaleSpace Primal Sketch: A Method for FocusofAttention
 INT. J. COMP. VISION
, 1993
"... This article presents: (i) a multiscale representation of greylevel shape called the scalespace primal sketch, which makes explicit both features in scalespace and the relations between structures at different scales, (ii) a methodology for extracting significant bloblike image structures from ..."
Abstract

Cited by 151 (14 self)
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This article presents: (i) a multiscale representation of greylevel shape called the scalespace primal sketch, which makes explicit both features in scalespace and the relations between structures at different scales, (ii) a methodology for extracting significant bloblike image structures from this representations, and (iii) applications to edge detection, histogram analysis, and junction classification demonstrating how the proposed method can be used for guiding later stage visual processes. The representation gives a qualitative description of image structure, which allows for detection of stable scales and associated regions of interest in a solely bottomup datadriven way. In other words, it generates coarse segmentation cues, and can hence be seen as preceding further processing, which can then be properly tuned. It is argued that once such information is available, many other processing tasks can become much simpler. Experiments on real imagery demonstrate that the proposed theory gives intuitive results.
Shape From Texture for Smooth Curved Surfaces in Perspective Projection
 Journal of Mathematical Imaging and Vision
, 1992
"... Projective distortion of surface texture observed in a perspective image can provide direct information about the shape of the underlying surface. Previous theories have generally concerned planar surfaces; in this paper we present a systematic analysis of first and secondorder texture distortion ..."
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Cited by 49 (6 self)
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Projective distortion of surface texture observed in a perspective image can provide direct information about the shape of the underlying surface. Previous theories have generally concerned planar surfaces; in this paper we present a systematic analysis of first and secondorder texture distortion cues for the case of a smooth curved surface. In particular, we analyze several kinds of texture gradients and relate them to surface orientation and surface curvature. The local estimates obtained from these cues can be integrated to obtain a global surface shape, and we show that the two surfaces resulting from the wellknown tilt ambiguity in the local foreshortening cue typically have qualitatively different shapes. As an example of a practical application of the analysis, a shape from texture algorithm based on local orientationselective filtering is described, and some experimental results are shown. i Figure 1: This image of a slanting plane covered with circles illustrates several...
Shape from Texture and Contour by Weak Isotropy
 J. of Artificial Intelligence
, 1993
"... A unified framework for shape from texture and contour is proposed. It is based on the assumption that the surface markings are not systematically compressed, or formally, that they are weakly isotropic. The weak isotropy principle is based on analysis of the directional statistics of the projected ..."
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Cited by 25 (6 self)
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A unified framework for shape from texture and contour is proposed. It is based on the assumption that the surface markings are not systematically compressed, or formally, that they are weakly isotropic. The weak isotropy principle is based on analysis of the directional statistics of the projected surface markings. It builds on several previous theories, in particular by Witkin [25] and Kanatani [15]. It extends these theories in various ways, most notably to perspective projection. The theory also provides an exact solution to an estimation problem earlier solved approximately by Kanatani. The weak isotropy principle leads to a computationally efficient algorithm, WISP, for estimation of surface orientation. WISP uses simple image observables that are shown to be direct correlates of the surface orientation to compute an initial approximate estimate in a single step. In certain simple cases this first estimate is exact, and in experiments with natural images it is typically within 5...
A Twocomponent Model of Texture for Analysis and Synthesis
, 1998
"... A model of natural texture based on a structural component which uses affine coordinate transformations and a stochastic residual component is presented. It is argued that the selection of an appropriate analysis scale can be formulated in terms of a tradeoff between the rate at which parameters ..."
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Cited by 21 (5 self)
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A model of natural texture based on a structural component which uses affine coordinate transformations and a stochastic residual component is presented. It is argued that the selection of an appropriate analysis scale can be formulated in terms of a tradeoff between the rate at which parameters are generated and the distortion resulting from the approximation by the structural component. An efficient algorithm for identifying the parameters of the structural model is described and its utility demonstrated on a number of synthetic and natural textures. 1 Introduction The analysis and synthesis of natural textures is one of the most intriguing and difficult problems in image processing, which has received much attention over the years [2, 20, 26, 21, 16, 10, 34, 35, 5, 4, 17]. Apart from their significance in applications ranging from remote sensing to computer graphics, the analysis and synthesis of texture have remained challenging problems because of the combination of stru...
Matching Perspective Views of Coplanar Structures using Projective Unwarping and Similarity Matching
 IN PROC.INT.CONF. OF COMPUTER VISION AND PATTERN RECOGNITION, CVPR
, 1994
"... We consider the problem of matching perspective views of coplanar structures composed of line segments. Both modeltoimage and imagetoimage correspondence matching are given a consistent treatment. These matching scenarios generally require discovery of an eight parameter projective mapping. Howe ..."
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Cited by 19 (5 self)
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We consider the problem of matching perspective views of coplanar structures composed of line segments. Both modeltoimage and imagetoimage correspondence matching are given a consistent treatment. These matching scenarios generally require discovery of an eight parameter projective mapping. However, when the horizon line of the object plane can be found in the image, done here using vanishing point analysis, these problems reduce to a simpler six parameter affine matching problem. When the intrinsic lens parameters of the camera are known, the problem further reduces to four parameter affine similarity matching.
Direct Estimation of Shape from Texture
 IEEE Transactions on Pattern Analysis and Machine Intelligence
, 1992
"... In [12], Witkin proposed a maximum likelihood (ML) estimator of surface orientation based on the observed directional bias of projected texture elements. However, a drawback of this procedure is that the estimate is only defined indirectly in terms of a set of nonlinear equations. In this paper we ..."
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Cited by 9 (1 self)
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In [12], Witkin proposed a maximum likelihood (ML) estimator of surface orientation based on the observed directional bias of projected texture elements. However, a drawback of this procedure is that the estimate is only defined indirectly in terms of a set of nonlinear equations. In this paper we propose an alternative method, which allows an estimate of the surface orientation to be computed directly in a single step from certain simple statistics of the image data. We also show that this direct estimate allows Witkin's ML estimate to be computed to within 0:05 ffi in only two or three iterative steps. The performance of the new estimator is demonstrated experimentally and compared to that of the ML estimator, using both synthetic data and real graylevel images. Index Terms: Shape from texture, surface orientation, foreshortening, isotropy, distributions on the circle, maximum likelihood, method of moments i 1 Introduction Although direct information about depth and threedim...
Adaptive Scale Filtering: A General Method for Obtaining Shape From Texture
 IEEE Trans. Pattern Anal. Machine Intell
, 1995
"... this paper, these modified versions are basically the same as those described in [8, 1]. Other shape from texture methods (see [13]) have also been tested using other images, with similar results to those presented here. Detailed results are presented for method K&C. This method assumes that the tex ..."
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Cited by 8 (0 self)
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this paper, these modified versions are basically the same as those described in [8, 1]. Other shape from texture methods (see [13]) have also been tested using other images, with similar results to those presented here. Detailed results are presented for method K&C. This method assumes that the texture on the surface is homogeneous in a sense which amounts informally to assuming that the distribution of surface texture in the image is the same as the distribution of surface area in the image.
Texture Analysis using the Multiresolution Fourier Transform
 In Scandinavian Conference on Image Analysis
, 1993
"... A new frequency domain approach to the analysis of texture is described. The method works by identifying, for pairs of texture `patches' of a given size, the affine coordinate transformation which gives the best match between them. This allows the analysis to take account of the geometric warping w ..."
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Cited by 8 (3 self)
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A new frequency domain approach to the analysis of texture is described. The method works by identifying, for pairs of texture `patches' of a given size, the affine coordinate transformation which gives the best match between them. This allows the analysis to take account of the geometric warping which is typically found in images of natural textures. The scheme is implemented efficiently in the Fourier domain, and, by variation of scale using the Multiresolution Fourier Transform (MFT), it is possible to identify the smallest scale which gives acceptable results in the matching process. The technique has the potential to deal effectively with textures having varying amounts of structure and can be used both for segmentation and resynthesis of textures from a single prototype block. 1 Introduction The analysis of textures is one of the oldest problems in image processing, but continues to generate interest and a degree of controversy because of the limited success with which most of ...
Image Representation Based On The Affine Symmetry Group
, 1996
"... The representation of 2D signals which are symmetric under the affine group of transformations is considered. An extension of the Multiresolution Fourier Transform (MFT) is presented and shown to have a predictable redistribution of energy as a result of affine transformations of the input signal. ..."
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Cited by 7 (1 self)
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The representation of 2D signals which are symmetric under the affine group of transformations is considered. An extension of the Multiresolution Fourier Transform (MFT) is presented and shown to have a predictable redistribution of energy as a result of affine transformations of the input signal. An approximation based on the discrete MFT then forms the basis of a computationally efficient algorithm for estimating local affine coordinate transformations between pairs of image regions. Results of applying the technique to an image registration problem illustrate its potential.
Direct computation of shape cues by multiscale retinotopic processing
 J. OF COMPUTER VISION
, 1994
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