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Recently, sample-based texture synthesis techniques have drawn significant attention from researchers. These existing approaches mainly use the Markov Random Field (MRF) or texture features as texture model to analyze the local properties of sample textures. Indeed, human perception is sensitive to structure and periodicity. In this paper, we perform texture synthesis by taking into account the distribution of texels. Given a sample texture, the analysis procedure consists in segmenting texture into individual texels, and detecting each texel in order to analyze their neighborhood relationships by constructing connectivity. Then the synthesis process consists in reproducing a new large texture directly on a user-specified canvas by recomposing segmented texels, which synthesizes two-dimensional texel arrangements based on the previously constructed neighborhood relationships of texels. Results show that the proposed method is successful in generating textures visually indistinguishable to the sample textures. Moreover, the method especially deals with the near-regular textures, which well preserves underlying structural regularity. [ABSTRACT FROM AUTHOR]

Camera calibration is a necessary step in many computer vision or photogrammetry tasks. During the execution of these tasks, initial camera calibration may be no longer valid because of intentional or accidental changes of camera parameters. We propose a camera on-line recalibration framework which is aimed at automatically maintaining the calibration of computer vision or photogrammetry system without using any particular calibration pattern again and interrupting the execution of the tasks. The proposed framework consists of initial calibration, followed by recalibration based on SIFT feature point detector and descriptor and a feature point match strategy proposed by us. Both synthetic data and real data have been used to test the framework, and very good results have been obtained. The experimental results of the framework are also compared with those of general on-line self-calibration methods. Both accuracy and speed are also reported. The proposed on-line recalibration framework yields higher accuracy and higher speed on calibrating camera parameters than on-line self-calibration methods do. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates techniques used in locating and determining the components on a printed circuit board (PCB) used for surface mount device inspection. The two phases involved in the proposed scheme include solder joint extraction and protective coating extraction. Results demonstrate that the novel approach can extract most of components in an effective manner.

The article presents a study, which proposes for an extended photometric stereo algorithm for the recovery of the shape of a surface with specularities and its reflectance properties. The study seeks to represent any potential specular reflection as a linear combination of specular terms with predetermined roughness values. It shows that the photometric stereo algorithm can deal with any isotropic reflection.

Color transfer is an image processing technique which can produce a new image combining one source image's contents with another image's color style. While being able to produce convincing results, however, Reinhard et al.'s pioneering work has two problems—mixing up of colors in different regions and the fidelity problem. Many local color transfer algorithms have been proposed to resolve the first problem, but the second problem was paid few attentions. In this paper, a novel color transfer algorithm is presented to resolve the fidelity problem of color transfer in terms of scene details and colors. It's well known that human visual system is more sensitive to local intensity differences than to intensity itself. We thus consider that preserving the color gradient is necessary for scene fidelity. We formulate the color transfer problem as an optimization problem and solve it in two steps—histogram matching and a gradient-preserving optimization. Following the idea of the fidelity in terms of color and gradient, we also propose a metric for objectively evaluating the performance of example-based color transfer algorithms. The experimental results show the validity and high fidelity of our algorithm and that it can be used to deal with local color transfer. [ABSTRACT FROM AUTHOR]

Purely rotation-based self-calibration receives the most attention among various self-calibration methods, owing to its algorithmic simplicity. However, it is actually impossible to ensure that the camera motion for this kind of self-calibration is a pure rotation, since the rotation center should--but unfortunately may never--completely coincide with the optical center with an unknown position. Almost all conventional pure rotation methods tend to ignore any translation, so the significant errors of calibration results could be inevitably introduced. We propose a practical and effective approach to improve the purely rotation-based self-calibration approach. The proposed approach accounts for translational offsets. According to the fact that the rotational angles between camera orientations have a very strong impact on the calibration errors from the translations, we compute the relative camera orientations prior to calibrating, then use different and very appropriate strategies for self-calibration in different angle circumstances, to achieve better calibration results. Both synthetic data and real data are used to test the proposed approach and very good results are obtained. Comparing the experimental results with those of conventional methods, the proposed approach significantly yields higher accuracy, and therefore reduces the calibration errors by the translations. [ABSTRACT FROM AUTHOR]

Abstract  We present a novel mesh denoising and smoothing method in this paper. Our approach starts by estimating the principal curvatures and mesh saliency value for each vertex. Then, we calculate the uniform principal curvature of each vertex based on the weighted average of local principal curvatures. After that, we use the weighted bi-quadratic Bézier surface to fit the neighborhood of each vertex using the least-square method and obtain the new vertex position by adjusting the parameters of the fitting surface. Experiments show that our smoothing method preserves the geometric feature of the original mesh model efficiently. Our approach also prevents the volume shrinkage of the input mesh and obtains smooth boundaries for non-closed mesh models. [ABSTRACT FROM AUTHOR]

This paper presents a virtual sculpting method for interactive 3D object deformation. The method is based on the use of an electronic glove. A parametric control hand surface defined by an open-uniform B-spline tensor product surface is first created to model the hand gesture. The geometric attributes of the object in the Euclidean 3D space are then mapped to the parametric domain of the control hand surface through a ray projection method. By maintaining the distances between the mapped pairs, change of hand gesture can be efficiently transferred to control the deformation of the object. Copyright © 2000 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]