1 INTRODUCTION

THE PURPOSE OF digital image processing is threefold; to improve the appearance of an image to a human observer, to extract from an image quantitative information that is not readily apparent to the eye, and to calibrate an image in photometric or geometric terms. Image processing is an art as well as a science. It is a multidisciplinary field which contains elements of photography, computer technology, optics, electronics, and mathematics.

Image processing was first developed largely in response to the needs of the space program. The Jet Propulsion Laboratory (JPL) of the California Institute of Technology began working in the field over twenty years ago. In 1965 JPL established the Image Processing Laboratory (IPL)1 in support of NASA's unmanned spacecraft exploration of the moon and planets. But in recent years, these techniques have found wide application outside this initial application. Medical science has applied digital image processing; Landsat images have led to more efficient oil exploration. mining, improved forest management, and the measurement of broad scale insect infestation. A newly developed area of application is in conservation research and condition documentation, an example of which is the study at hand.