Now showing items 1-10 of 85
Optimally Weighted Highpass Filters using Multiscale Analysis
An obvious approach to image enhancement is to sharpen bright regions of an image more than darker regions. One very simple method to accomplish this is to weight the amount of highpass filtering proportional to the local mean. This gives rise to a class of nonlinear image enhancement filters known as mean-weighted highpass filters. We propose a ...
Hybrid Linear/Quadratic Time-Frequency Attributes
We present an efficient method for robustly calculating time-frequency attributes of a signal, including instantaneous mean frequency, bandwidth, kurtosis, and other moments. Most current attribute estimation techniques involve a costly intermediate step of computing a (highly oversampled) two-dimensonal (2-D) quadratic time-frequency representation ...
Applications of Terahertz Imaging
The recent advances involving imaging with sub-picosecond terahertz pulses have opened up a wide range of possibilities in the applications of far-infrared technology. For the first time, a commercially viable terahertz imaging spectrometer seems a realizable prospect. However, several substantial engineering research challenges remain to be overcome ...
Throughput Measures for Delay-constrained Communications in Fading Channels
Fading channels, often seen in wireless systems, provide an unfavorable environment for reliable communications. Current methods for evaluating the performance of fading channels include ergodic capacity and <i>epsilon</i>-capacity. Ergodic capacity quantifies the ultimate reliable communication limit of the fading channel. It is only achievable with ...
JPEG Compression History Estimation for Color Images
We routinely encounter digital color images that were previously compressed using the Joint Photographic Experts Group (JPEG) standard. En route to the image's current representation, the previous JPEG compression's various settingsâ termed its JPEG compression history (CH)â are often discarded after the JPEG decompression step. Given a JPEG-decompressed ...
Sparse Signal Detection from Incoherent Projections
The recently introduced theory of Compressed Sensing (CS) enables the reconstruction or approximation of sparse or compressible signals from a small set of incoherent projections; often the number of projections can be much smaller than the number of Nyquist rate samples. In this paper, we show that the CS framework is information scalable to a wide ...
Optimal Transmit Spectra for Communication in the Presence of Crosstalk and Imperfect Echo Cancellation
In many communication systems, including Digital Subscriber Lines, performance is severely limited by crosstalk interference. Previous work has presented a general framework for designing optimal transmit spectra for crosstalk avoidance . The technique uses the channel, noise, and interference characteristics to setup and solve an optimization problem ...
An On-Line Signal-Dependent Time-Frequency Representation
Blind Crosstalk Cancellation for DMT Systems
As the deployment of broadband communication systems such as DSL continues to grow, system performance in terms of capacity and error rates is severely limited by crosstalk interference. In order to continue deploying high speed DSL service, it becomes necessary to mitigate this crosstalk interference. All current crosstalk mitigation techniques ...
Network and User Driven Alpha-Beta Onâ Off Source Model for Network Traffic
We shed light on the effect of network resources and user behavior on network traffic through a physically motivated model. The classical onâ off model successfully captures the long-range, second-order correlations of traffic, allowing us to conclude that transport protocol mechanisms have little influence at time scales beyond the round trip time. ...