In this paper, we present a new entropy-based minimum description length (MDL) criterion for simultaneous classification and visual word selection. Conventional MDL criteria focus on how to minimize cluster size and m...
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ISBN:
(纸本)0769525210
In this paper, we present a new entropy-based minimum description length (MDL) criterion for simultaneous classification and visual word selection. Conventional MDL criteria focus on how to minimize cluster size and maximize the likelihood of data points. We extend the MDL by replacing the likelihood term with the entropy of class posterior. This new criterion can provide optimal visual words with enough classification accuracy. We validate the entropy-based MDL to learn optimal visual words for place classification and categorization of the Caltech 101 object database
We present a probabilistic technique for matching part-based shapes. Shapes are represented by unlabeled point sets, so discontinuous boundaries and non-boundary points do not pose a problem. Occlusions and significan...
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We present a probabilistic technique for matching part-based shapes. Shapes are represented by unlabeled point sets, so discontinuous boundaries and non-boundary points do not pose a problem. Occlusions and significant dissimilarities between shapes are explained by a 'background model' and hence, their impact on the overall match is limited. Using a part-based model, we can successfully match shapes which differ as a result of independent part transformations - a form of variation common amongst real objects of the same class. A greedy algorithm that learns the parts sequentially can be used to estimate the number of parts and the initial parameters for the main algorithm
"Caltech Calibration Toolbox" by Jean-Yves Bouguet is one of the most famous open-source calibration tools. Although it works well for general camera lenses, it reveals problems in case of wide-angle lens. T...
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ISBN:
(纸本)0769525210
"Caltech Calibration Toolbox" by Jean-Yves Bouguet is one of the most famous open-source calibration tools. Although it works well for general camera lenses, it reveals problems in case of wide-angle lens. This paper analyzes the problem and shows that the insufficient calibration of radial distortion is caused by lease-square based polynomial fitting. To overcome the problem, this paper proposes novel refinement method using inverse mapping-based extrapolation. The proposed method is expected to be an efficient supplement and is opened to the public in the appendix as a short Matlab script
In this paper, we propose new camera calibration methods assuming a static camera. Two corresponding imaged rectangles whose aspect ratios are unknown are sufficient to calibrate a camera. By warping the images proper...
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ISBN:
(纸本)0769525210
In this paper, we propose new camera calibration methods assuming a static camera. Two corresponding imaged rectangles whose aspect ratios are unknown are sufficient to calibrate a camera. By warping the images properly, we show that the information from the imaged rectangles can be transformed to the form of camera constraints. Based on these results, we propose two methods, one for three or more images and the other for only two images. The proposed methods are verified with synthetic and real images, and the results are comparable with less assumption on cameras and on scenes
In this paper we propose a novel technique to image completion that addresses image renaissance through a graph-based matching process. To this end, a number of candidate seeds with content similar to the one of the a...
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In this paper we propose a novel technique to image completion that addresses image renaissance through a graph-based matching process. To this end, a number of candidate seeds with content similar to the one of the area to be inpainted are considered. They are selected through a particle filter method and then positioned over the missing area. Markov random fields are used to formalize inpainting as a labeling estimation problem while a combinatorial approach is used to recover the optimal partition of patches that completes the missing area with the alpha-expansion process. Promising results in image and texture completion demonstrate the potentials of the proposed method
While face detection seems a solved problem under general conditions, most state-of-the-art systems degrade rapidly when faces are partially occluded by other objects. This paper presents a solution to detect partiall...
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ISBN:
(纸本)0769525210
While face detection seems a solved problem under general conditions, most state-of-the-art systems degrade rapidly when faces are partially occluded by other objects. This paper presents a solution to detect partially occluded faces by reasonably modifying the AdaBoost-based face detector. Our basic idea is that the weak classifiers in the AdaBoost-based face detector, each corresponding to a Haar-like feature, are inherently a patch-based model. Therefore, one can divide the whole face region into multiple patches, and map those weak classifiers to the patches. The weak classifiers belonging to each patch are re-formed to be a new classifier to determine if it is a valid face patch - without occlusion. Finally, we combine all of the valid face patches by assigning the patches with different weights to make the final decision whether the input subwindow is a face. The experimental results show that the proposed method is promising for the detection of occluded faces
Texture boundaries or edges are useful information for segmenting a texture image. We propose a texture edge detection algorithm using a bank of 1D multi-channel, multi-resolution filters and self organizing map (SOM)...
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Texture boundaries or edges are useful information for segmenting a texture image. We propose a texture edge detection algorithm using a bank of 1D multi-channel, multi-resolution filters and self organizing map (SOM). 2D filtering smears the effect of an edge in all directions, and hence we used 1D filtering that will only smear the edge in the direction of filtering. SOM reduces the dimension of a feature vector by producing a 1D map which plots the similarities of data by grouping similar items together. The output of SOM is processed to obtain the texture edge map. The proposed methodology is tested on simulated as well as natural texture images and produces satisfactory results
In industrial quality inspection obtaining the training data needed for classification problems is still a very costly task. Nevertheless, the classifier quality is crucial for economic success. Thus, the question whe...
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In industrial quality inspection obtaining the training data needed for classification problems is still a very costly task. Nevertheless, the classifier quality is crucial for economic success. Thus, the question whether the influence of the training data on the classification error has been fully exploited and enough data has been obtained is very important. This paper introduces a method to answer this question for a specific problem. To be able to make a concrete statement and not only general recommendations, we focus on the k-NN classifier, since it is widely used in industrial implementations. The method is tested on four different multiclass problems: original data from an optical media inspection problem, the MNIST database, and two artificial problems with known probability densities
Face pose estimation forms an important part in a face recognition system. However, fully automated and accurate pose determination still remains an unsolved problem in the research community. In this paper, we propos...
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Face pose estimation forms an important part in a face recognition system. However, fully automated and accurate pose determination still remains an unsolved problem in the research community. In this paper, we propose a novel elastic energy model to automatically estimate face poses. Our method employs statistical energy contributions of a set of feature points, which can avoid over-trusting selected anchor points. It provides a robust solution to the feature localisation inaccuracy problem, which is inevitable in practical applications with cluttered backgrounds. As a general configuration, our model can be easily implemented and extended to other non-rigid objects. Its effectiveness and robustness are revealed in our experiments
We introduce an efficient method for recovering the camera parameters automatically from the cast shadows of two 3D points observed over time. Compared to previous related work, our method has less restrictions in the...
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ISBN:
(纸本)0769525210
We introduce an efficient method for recovering the camera parameters automatically from the cast shadows of two 3D points observed over time. Compared to previous related work, our method has less restrictions in the sense that object-to-shadow correspondences do not have to be available in the image. We demonstrate how the horizon line may be recovered from only shadow points, and how the camera intrinsic and extrinsic parameters are determined using the pole-polar relationship and minimizing the algebraic distance of the principal point. The approach is fully validated on both synthetic and real data, and tested against various sources of error. We finally present an application to metrology from shadows only - i.e. when the object is not visible in the image
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