Stephen Herman

Locally-adaptive processing of television images based on real-time image segmentation

Current methods of processing television images at the receiver are either performed globally, or locally with globally constant parameters. By contrast, greater levels of enhancement can be achieved if television images are segmented into regions of similar features. Then, each region is enhanced using algorithms optimized for the local properties of the segment. New methods of segmentation have been developed to allow for real-time processing at video rates. Some examples of this include grass and sky detection. We present models for color, luminance, position and texture that have been successfully used to identify grass and sky areas in TV images.

Ferroelectric capacitors for discharge lamp ballast circuits

Abstract Discharge-lamp ballast circuits of the type commonly used in the USA utilize an organic ballast capacitor. We have shown that substituting a ferroelectric ceramic capacitor with its dielectric nonlinearity improves the performance of the ballast circuit. Fluorescent and other discharge lamps operate more efficiently, and the ballast transformer circuit power losses are reduced. We will show that the ballast related characteristics of such nonlinear capacitors can be described by six parameters of an equation which represents the nonlinearities as well as hysteresis. A high-precision computer simulation was used to optimize the ballast-capacitor combination and find the shape of optimum nonlinearities. A tolerance study was also performed on the capacitor parameters. Extensive in-circuit testing of several different materials was used to define system and material requirements.

Commercial Echo Canceller For Television

Cancellation of television ghost images promises to improve the quality of NTSC reception. However, receivers with cancellation abilities can not be used until the broadcasters transmit a requisite reference signal. This paper will describe some ghost cancellation systems, will touch on the issues that go into a choice for such a reference signal and describe preliminary results of field tests with two such reference signals.

Some Simple Generalizations Of Morphological Filters

Morphological operators such as erosion, dilation, opening and closing have been used for image processing. These classical operators modify an image feature based only on the size and polarity of that feature. We introduce a 3 by 3 pixel operator which can be used to perform repeated erosion and dilation like operations that are functions of not only size and polarity, but also local derivatives or ratios of adjacent pixel values. These operations can be mixed to implement new types of nonlinear filtering functions. Examples are given in 1 and 2 dimensions.

An Introduction To Sifting Theory

A common class of nonlinear signal and image processing methods involves the use of median filters or the more general rank-ordered operators. Sifting theory models these operators in a manner that allows intuitive parallels to be drawn to analogous linear filtering procedures. Such insights should provide guidance on how to utilize these available techniques and synthesize new ones.