Nonlinear Image Processing

Image Enhancement and

Analysis with Weighted

Medians

GONZALO R. ARCE AND JOSE L. PAREDES*

Department of Electrical and Computer Engineering

University of Delaware

Newark, Delaware

2.1 Introduction

Digital image enhancement and analysis have played and will continue to play an

important role in scientific, industrial, and military applications. In addition to

these, image enhancement and analysis are being used increasingly in consumer

electronics. World Wide Web users, for instance, not only rely on built-in image

processing protocols such as JPEG and interpolation but also have become image

processing users equipped with powerful yet inexpensive software such as Pho-

toShop. Users not only retrieve digital images from the Web but now are able to

acquire their own by use of digital cameras or through digitization services of

standard 35-mm analog film. The end result is that consumers are beginning to

use home computers to enhance and manipulate their own digital pictures.

Image enhancement tools are often classified into (a) point operations and (b)

spatial operators. Point operations include contrast stretching, histogram modi-

fication, and pseudo-coloring. Point operations are, in general, simple nonlinear

*Jos~ L. Paredes is also with the Electrical Engineering Department, University of Los Andes,

M~rida-Venezuela.

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