Adaptive Filter Techniques For Digital Image Enhancement

A survey of several adaptive techniques for image enhancement and filtering is presented under a com-mon framework. With the proliferation high-speed processors, such as array and image display processors, the increased computational power has shifted emphasis in image processing away from "global" to "local" techniques. These local techniques frequently use sliding windows which compute local properties of the image. These properties, in turn, are used to locally control the enhancement or filter applied to the image. The types of operations discussed encompass contrast, edge or information enhancment, noise or artifact reduction, and feature extraction or removal. Algorithmic implementations include real-time con-trast enhancement filters, zonal filters, short-space FFT filters, and a multi-dimensional adaptive least-squares technique. In this review paper, an adaptive frame-work, discussions on various enhancement approaches, and an extensive bibliography are presented.