Author
C. Paramanand
Bio: C. Paramanand is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Image restoration & Motion blur. The author has an hindex of 4, co-authored 6 publications receiving 68 citations.
Papers
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TL;DR: This paper proposes and develops a formulation of unscented Kalman filter for depth estimation, and addresses a special and challenging scenario of depth from defocus with translational jitter.
Abstract: Space-variantly blurred images of a scene contain valuable depth information. In this paper, our objective is to recover the 3-D structure of a scene from motion blur/optical defocus. In the proposed approach, the difference of blur between two observations is used as a cue for recovering depth, within a recursive state estimation framework. For motion blur, we use an unblurred-blurred image pair. Since the relationship between the observation and the scale factor of the point spread function associated with the depth at a point is nonlinear, we propose and develop a formulation of unscented Kalman filter for depth estimation. There are no restrictions on the shape of the blur kernel. Furthermore, within the same formulation, we address a special and challenging scenario of depth from defocus with translational jitter. The effectiveness of our approach is evaluated on synthetic as well as real data, and its performance is also compared with contemporary techniques.
44 citations
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TL;DR: This work develops a technique to estimate the transformation spread function (TSF) which symbolizes the camera shake and recovers the complete depth map of the scene within a regularization framework using an unblurred–blurred image pair.
Abstract: Motion blur due to camera shake is a common occurrence. During image capture, the apparent motion of a scene point in the image plane varies according to both camera motion and scene structure. Our objective is to infer the camera motion and the depth map of static scenes using motion blur as a cue. To this end, we use an unblurred---blurred image pair. Initially, we develop a technique to estimate the transformation spread function (TSF) which symbolizes the camera shake. This technique uses blur kernels estimated at different points across the image. Based on the estimated TSF, we recover the complete depth map of the scene within a regularization framework.
21 citations
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13 Jun 2010TL;DR: It is shown that the relationship between the observation and the scale factor of the motion-blur kernel associated with the depth at a point is nonlinear and the use of the unscented Kalman filter for state estimation is proposed.
Abstract: In images and videos of a 3D scene, blur due to camera shake can be a source of depth information. Our objective is to find the shape of the scene from its motion-blurred observations without having to restore the original image. In this paper, we pose depth recovery as a recursive state estimation problem. We show that the relationship between the observation and the scale factor of the motion-blur kernel associated with the depth at a point is nonlinear and propose the use of the unscented Kalman filter for state estimation. The performance of the proposed method is evaluated on many examples.
5 citations
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01 Sep 2013TL;DR: This paper develops a method for motion segmentation using blur kernels to segment them according to their relative motion using transformation spread functions (TSFs) which represent the relative motions.
Abstract: In this paper, we develop a method for motion segmentation using blur kernels. A blur kernel represents the apparent motion undergone by a scene point in the image plane. When the relative motion between the camera and scene is not restricted to fronto-parallel translations, the shape of the blur kernels can vary across image points. For a dynamic scene, we effectively model motion blur using transformation spread functions (TSFs) which represent the relative motions. Given a set of blur kernels that are estimated at different points across an image, we develop a method to segment them according to their relative motion. We initially group the blur kernels based on their `compatibility'. We refine this initial segmentation by jointly estimating the TSF and removing the outliers.
5 citations
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TL;DR: A geometric matching technique in which line segments and elliptical arcs are used as edge features and the use of these higher-order features renders feature representation efficient.
Abstract: We propose a geometric matching technique in which line segments and elliptical arcs are used as edge features The use of these higher-order features renders feature representation efficient We derive distance measures to evaluate the similarity between the features of the model and those of the image The model transformation parameters are found by searching a 3-D transformation space using cell-decomposition The performance of the proposed method is quite good when tested on a variety of images
3 citations
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01 Nov 2015TL;DR: The basic theories of Kalman filter are introduced, and the merits and demerits of them are analyzed and compared, and relevant conclusions and development trends are given.
Abstract: Kalman filter is a minimum-variance estimation for dynamic systems and has attracted much attention with the increasing demands of target tracking. Various algorithms of Kalman filter was proposed for deriving optimal state estimation in the last thirty years. This paper briefly surveys the recent developments about Kalman filter (KF), Extended Kalman filter (EKF) and Unscented Kalman filter (UKF). The basic theories of Kalman filter are introduced, and the merits and demerits of them are analyzed and compared. Finally relevant conclusions and development trends are given.
240 citations
01 Apr 2005
TL;DR: This book is a comprehensive guide to the scientific and engineering principles of colour imaging that covers the physics of light and colour, how the eye and physical devices capture colour images, how colour is measured and calibrated, and how images are processed.
Abstract: Colour imaging technology has become almost ubiquitous in modern life in the form of monitors, liquid crystal screens, colour printers, scanners, and digital cameras. This book is a comprehensive guide to the scientific and engineering principles of colour imaging. It covers the physics of light and colour, how the eye and physical devices capture colour images, how colour is measured and calibrated, and how images are processed. It stresses physical principles and includes a wealth of real-world examples. The book will be of value to scientists and engineers in the colour imaging industry and, with homework problems, can also be used as a text for graduate courses on colour imaging.
116 citations
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TL;DR: A novel frame rate up-conversion method through high-order model and dynamic filtering (HOMDF) for video pixels that minimizes the auto-regressive prediction error of intensity variation by its past samples and minimizes video frame’s reconstruction error along the motion trajectory.
Abstract: This paper proposes a novel frame rate up-conversion method through high-order model and dynamic filtering (HOMDF) for video pixels. Unlike the constant brightness and linear motion assumptions in traditional methods, the intensity and position of the video pixels are both modeled with high-order polynomials in terms of time. Then, the key problem of our method is to estimate the polynomial coefficients that represent the pixel's intensity variation, velocity, and acceleration. We propose to solve it with two energy objectives: one minimizes the auto-regressive prediction error of intensity variation by its past samples, and the other minimizes video frame's reconstruction error along the motion trajectory. To efficiently address the optimization problem for these coefficients, we propose the dynamic filtering solution inspired by video's temporal coherence. The optimal estimation of these coefficients is reformulated into a dynamic fusion of the prior estimate from pixel's temporal predecessor and the maximum likelihood estimate from current new observation. Finally, frame rate up-conversion is implemented using motion-compensated interpolation by pixel-wise intensity variation and motion trajectory. Benefited from the advanced model and dynamic filtering, the interpolated frame has much better visual quality. Extensive experiments on the natural and synthesized videos demonstrate the superiority of HOMDF over the state-of-the-art methods in both subjective and objective comparisons.
45 citations
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TL;DR: This paper proposes and develops a formulation of unscented Kalman filter for depth estimation, and addresses a special and challenging scenario of depth from defocus with translational jitter.
Abstract: Space-variantly blurred images of a scene contain valuable depth information. In this paper, our objective is to recover the 3-D structure of a scene from motion blur/optical defocus. In the proposed approach, the difference of blur between two observations is used as a cue for recovering depth, within a recursive state estimation framework. For motion blur, we use an unblurred-blurred image pair. Since the relationship between the observation and the scale factor of the point spread function associated with the depth at a point is nonlinear, we propose and develop a formulation of unscented Kalman filter for depth estimation. There are no restrictions on the shape of the blur kernel. Furthermore, within the same formulation, we address a special and challenging scenario of depth from defocus with translational jitter. The effectiveness of our approach is evaluated on synthetic as well as real data, and its performance is also compared with contemporary techniques.
44 citations
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TL;DR: This study reviews several image processing methods in the feature extraction of leaves and discusses certain machine learning classifiers for an analysis of different species of leaves.
Abstract: Plants are fundamentally important to life. Key research areas in plant science include plant species identification, weed classification using hyper spectral images, monitoring plant health and tracing leaf growth, and the semantic interpretation of leaf information. Botanists easily identify plant species by discriminating between the shape of the leaf, tip, base, leaf margin and leaf vein, as well as the texture of the leaf and the arrangement of leaflets of compound leaves. Because of the increasing demand for experts and calls for biodiversity, there is a need for intelligent systems that recognize and characterize leaves so as to scrutinize a particular species, the diseases that affect them, the pattern of leaf growth, and so on. We review several image processing methods in the feature extraction of leaves, given that feature extraction is a crucial technique in computer vision. As computers cannot comprehend images, they are required to be converted into features by individually analyzing image shapes, colors, textures and moments. Images that look the same may deviate in terms of geometric and photometric variations. In our study, we also discuss certain machine learning classifiers for an analysis of different species of leaves.
38 citations