61448634
Single-Image Vignetting Correction
In this paper, we propose a method for determining the vignetting function given only a single image. Our method is designed to handle both textured and untextured regions in order to maximize the use of available information. To extract vignetting information from an image, we present adaptations of segmentation techniques that locate image regions with reliable data for vignetting estimation. Within each image region, our method capitalizes on frequency characteristics and physical properties of vignetting to distinguish it from other sources of intensity variation. The vignetting data acquired from regions are weighted according to a presented reliability measure to promote robustness in estimation. Comprehensive experiments demonstrate the effectiveness of this technique on a broad range of images.
47117010
Stylizing 2.5-D video
In recent years considerable interest has been given to non-photorealistic rendering of photographs, video, and 3D models for illustrative or artistic purposes. Conventional 2D inputs such as photographs and video are easy to create and capture, while 3D models allow for a wider variety of stylization techniques, such as cross-hatching. In this paper, we propose using video with depth information (2.5-D video) to combine the advantages of 2D and 3D input. 2.5-D video is becoming increasingly easy to capture, and with the additional depth information, stylization techniques that require shape information can be applied. However, because 2.5-D video contains only limited shape information and 3D correspondence over time is unknown, it is difficult to create temporally coherent stylized animations directly from raw 2.5-D video. In this paper, we present techniques for processing 2.5-D video to overcome these drawbacks, and demonstrate several styles that can be created using these techniques.
16190492
Noise Estimation from a Single Image
In order to work well, many computer vision algorithms require that their parameters be adjusted according to the image noise level, making it an important quantity to estimate. We show how to estimate an upper bound on the noise level from a single image based on a piecewise smooth image prior model and measured CCD camera response functions. We also learn the space of noise level functions how noise level changes with respect to brightness and use Bayesian MAP inference to infer the noise level function from a single image. We illustrate the utility of this noise estimation for two algorithms: edge detection and featurepreserving smoothing through bilateral filtering. For a variety of different noise levels, we obtain good results for both these algorithms with no user-specified inputs.
40596005
Survey of image-based representations and compression techniques
We survey the techniques for image-based rendering (IBR) and for compressing image-based representations. Unlike traditional three-dimensional (3-D) computer graphics, in which 3-D geometry of the scene is known, IBR techniques render novel views directly from input images. IBR techniques can be classified into three categories according to how much geometric information is used: rendering without geometry, rendering with implicit geometry (i.e., correspondence), and rendering with explicit geometry (either with approximate or accurate geometry). We discuss the characteristics of these categories and their representative techniques. IBR techniques demonstrate a surprising diverse range in their extent of use of images and geometry in representing 3-D scenes. We explore the issues in trading off the use of images and geometry by revisiting plenoptic-sampling analysis and the notions of view dependency and geometric proxies. Finally, we highlight compression techniques specifically designed for image-based representations. Such compression techniques are important in making IBR techniques practical.
44673585
Characterization of Errors in Compositing Panoramic Images
A panoramic image has a 360° horizontal field of view, and it can provide the viewer the impression of being immersed in the scene. A panorama is created by first taking a sequence of images while rotating the camera about a vertical axis. These images are then projected onto a cylindrical surface before being seamlessly composited. The cross-sectional circumference of the cylindrical panorama is called thecompositing length. This work characterizes the error in compositing panoramic images due to errors in some of the intrinsic parameters. The intrinsic camera parameters that are considered are the camera focal length and the radial distortion coefficient. We show that the error in the compositing length is more sensitive to the error in the camera focal length. Especially important is the discovery that the relative error in compositing length is always smaller than the relative error in the focal length. This means that the error in focal length can be corrected by iteratively using the composited length to compute a new and more correct focal length. Thiscompositing approach to camera calibrationhas the advantages of not requiring both feature detection and separate prior calibration.
2096181
Video editing using figure tracking and image-based rendering
We describe a new approach to video editing based on the semi-automatic segmentation of video into multiple layers and the composition of layers using image-based rendering. Using figure tracking and background motion estimation, we can segment a moving figure and reconstruct the background. Using geometrically-correct pixel reprojection, layers can be composited on the basis of the geometry of the underlying scene and the position of a virtual camera. We have implemented a prototype editing system called SpliceWorld.
29231099
A new circuit optimization technique for high performance CMOS circuits
A novel transistor sizing technique with a concise problem formulation and rigorous optimization scheme is described. A circuit optimization technique for high-performance CMOS circuits is presented for proper balance of chip speed and area. The timing specification is accommodated as a design constraint, and reliability issues in the charge sharing and noise margin, which have been neglected in previous optimization tools, are also embedded into the design constraints. The optimization scheme used in this approach does not require derivatives, and therefore, can be used for a broad class of continuous cost functions. Special attention is given to the most effective use of silicon area based on the sensitivity of the delay time with respect to the transistor size. Excessively large transistor sizes are avoided by using the resource redistribution scheme. This timing allocation scheme allows the computation time to be linearly proportional to the number of gates. >
353647
On Estimating Tight-Link Bandwidth Characteristics over Multi-Hop Paths
In this paper, we explore multi-hop bandwidth estimation assuming arbitrary cross-traffic at each node and develop a new probing method called Envelope that can asymptotically estimate not only the available bandwidth but also the raw capacity of the tight link. Envelope is based on a multi-link recursive extension of unbiased single-hop estimators proposed in the past (e.g., [14]) and a variation of the packet-cartouche technique [6]. Through extensive simulations, we evaluate Envelope in various network settings and cross-traffic conditions and find that it can measure tight-link bandwidth characteristics with accuracy that significantly surpasses that of the existing methods. We also find that Envelope can measure non-tight links in certain path and cross-traffic configurations.
9186181
New simulation methods for MOS VLSI timing and reliability
A novel approach to incorporating the channel length modulation in a direct-equation solving fast timing simulator is presented along with a mixed event-driven and waveform relaxation algorithm to handle MOS VLSI circuits with feedback. Simulation speedup of 3N over SPICE-like simulators has been observed, where N is the number of transistors. The simulator is able to simulate circuits as large as 235000 transistors in 10 min real time. Also presented is a novel approach to fast hot-carrier reliability simulation. These methods make it possible to achieve accurate and fast hot-carrier reliability simulation of MOS circuits each with as many as hundreds of thousands of MOS transistors in a workstation environment.<<ETX>>
8347342
Keyword-based document clustering
Document clustering is an aggregation of related documents to a cluster based on the similarity evaluation task between documents and the representatives of clusters. Terms and their discriminating features of terms are the clue to the clustering and the discriminating features are based on the term and document frequencies. Feature selection method on the basis of frequency statistics has a limitation to the enhancement of the clustering algorithm because it does not consider the contents of the cluster objects. In this paper, we adopt a content-based analytic approach to refine the similarity computation and propose a keyword-based clustering algorithm. Experimental results show that content-based keyword weighting outperforms frequency-based weighting method.
32568915
Event Sentence Extraction in Korean Newspapers
Information extraction is to extract information about the main events in the text. This paper presents an event sentence extraction method in Korean newspapers for information extraction. Event sentences contain meaningful information such as the agent, the time and the place of an event. To extract these sentences, we acquire various features such as verbs, nouns, noun phrases, 3Ws, and their weights. And then, the system computes weights of sentences and extracts event sentences by our extraction algorithm. The experimental result shows the average precision of 86.1%.