OBJECTIVE Preoperative magnetic resonance imaging (MRI), functional MRI, diffusion tensor MRI, magnetic resonance spectroscopy, and positron-emission tomographic scans may be aligned to intraoperative MRI to enhance visualization and navigation during image-guided neurosurgery. However, several effects (both machine- and patient-induced distortions) lead to significant geometric distortion of i...

Non-linear distortion of OFDM signals can significantly increase the receiver BER. Currently, distortion analyses rely on simulation, not yielding insight into the problem, or apply to specific non-linearities only. In this paper, general analytic results are presented on the errors resulting from distortion. The results are applicable to smooth non-linear distortion of an OFDM signal, which is...

Asymptotic expressions for the optimal scaling factor and resulting minimum distortion , as a function of codebook size N, are found for xed-rate k-dimensional lattice vector quantization of generalized Gaussian sources with decay parameter 1. These expressions are derived by minimizing upper and lower bounds to distortion. It is shown that the optimal scaling factor a N decreases as (lnN) 1== ...

In this paper a perceptual video distortion measure system based on the human vision model is presented. This system is an extension of the still perceptual distortion measure system. One advantage of the distortion measure is that the distortion can be weighted for frames in the vicinity of scene cuts. Our video distortion measure also requires less computation compared to other approaches. Th...

In this paper we propose a new method to automatically correct wide-angle lens distortion from the distorted lines generated by the projection on the image of 3D straight lines. We have to deal with two major problems: on the one hand, wide-angle lenses produce a strong distortion, which makes the detection of distorted lines a particularly difficult task. On the other hand, the usual single pa...

For user convenience, document image processing captured with a digital camera instead of a scanner has been researched. However, existing methods of document image processing are not usable for a perspective document image captured by a digital camera because most of them are designed for the one captured by a scanner. Thus, we have to rectify the perspective of the document image and obtain t...

Previous work on camera calibration, and particularly work on self-calibration, has assumed that the camera is well modeled by an ideal, relatively simple, parametric model. Real camera systems, however, diverge signiicantly from a simple pinhole perspective imaging model. Therefore, parametric calibration models are typically extended to include parameters which model distortions from perspect...

aqueous polymer quenchants are being used increasingly in steel heat treatment industries as a substitution for conventional quenchants. by adjusting the quench parameters of the polymeric media, it is possible to achieve desirable microstructure and mechanical properties in addition to reduction in distortion and cracking. in this work, polyalkylene glycol (pag) aqueous solution was used as th...

We develop new rate distortion bounds for narrowband and wideband speech coding based on composite source models for speech and perceptual PESQ-MOS/WPESQ distortion measures. It is shown that these new rate distortion bounds do in fact lower bound the performance of important standardized speech codecs, including, G.726, G.727, AMR-NB, G.729, G.718, G.722, G.722.1, and AMR-WB. The approach is t...

This paper presents the results of three psychophysical experiments designed to investigate the effects of spatial correlations and the disruption of global precedence on the visual fidelity of natural images. The first two experiments used a psychophysical scaling paradigm in which subjects placed distorted images along a linear, one-dimensional “distortion axis” where physical distance corres...