XII Preface to the First Edition
with means for correction. This also contains material on registration of images to
maps and images to each other. Here, as in all techniques chapters, real and modelled
image data examples are given. Chapter 3 establishes the role of computer processing
both for photointerpretation by a human analyst and for machine analysis. This may
be skipped by the remote sensing professional but is an important position chapter
if the book is to be used in teaching.
Chapters 4 and 5 respectively cover the range of radiometric and geometric en-
hancement techniques commonly adopted in practice, while Chap. 6 is addressed to
multispectral transformations of data. This includes the principal components trans-
formation and image arithmetic. Chapter 7 is given over to Fourier transformations.
This material is becoming more important in remote sensing with falling hardware
costs and the ready availability of peripheral array processors. Here the properties
of discrete Fourier analysis are given along with means by which the fast Fourier
transform algorithm can be used on image data.
Chapters 8, 9 and 10 provide a treatment of the tools used in image classification,
commencing with supervised classification methods, moving through commonly
used clustering algorithms for unsupervised classification and concluding with means
for separability analysis. These are drawn together into classification methodologies
in Chap. 11 which also provides a set of case studies.
Even though the treatment provided is intended for the non-specialist image
analyst, it is still necessary that it be cast in the context of some vector and matrix
algebra. Otherwise it would be impracticable. Consequently, an appendix is provided
on essential results on vectors and matrices, and all important points in the text are
illustrated by simple worked examples. These demonstrate how vector operations are
evaluated. Beyond this material it is assumed the reader has a passing knowledge of
basic probability and statistics including an appreciation of the multivariate normal
distribution.
Several other appendices are provided to supplement the main presentation. One
deals with developments in image processing hardware and particularly the archi-
tecture (in block form) of interactive image display sub-systems. This material high-
lights trends towards hardware implementation of image processing and illustrates
how many of the algorithms presented in the book can be executed in near real time.
Owing to common practice, some decisions have had to be taken in relation to
definitions even though they could offend the purist. For example the term “pixel"
strictly refers to a unit of digital image data and not to an area on the ground. The latter
is more properly called an effective ground resolution element. However because the
practice of referring to ground resolution elements as pixels, dimensioned in metres,
is so widespread, the current treatment seeks not to be pedantic but rather follows
common practice for simplicity. A difficulty also arises with respect to the numbering
chosen for the wavebands in the Landsat multispectral scanner. Historically these
have been referred to as bands 4 to 7 for Landsats 1 to 3. From Landsat 4 onwards
they have been renumbered as bands 1 to 4. The convention adopted herein is mixed.
When a particular satellite is evident in the discussion, the respective convention is