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INTRODUCTION 
A number of investigators have proposed unsupervised clas 
sification schemes for ERTS data. Most consist of some form of 
cluster analysis on all four bands of the MSS computer compatible 
tapes, and while many are available in well-documented packages, 
they are not remarkably successful in comparison with supervised 
techniques; where the supervised techniques require tedious 
iteration of certain basic procedures, the unsupervised classi 
fiers substitute one-£ass consumption of exorbitant amounts of 
computer time, with little or no increase in classification 
accuracy. No criticism of advanced processing techniques or basic 
research is intended here; clearly, more sophisticated machine 
processing methods are vital to even approach optimum utilization 
of the data which will be supplied by ERTS and its successors. 
However, information of the nature of that provided by ERTS is 
urgently needed in many fields, and in the interest of early 
realization of its potential by those with little opportunity 
for extensive re-education, it should be noted that the nature 
of the data is such that even simple operations can produce re 
markable results. 
There is little reason for the land planner, ecologist, or 
limnologist, typically interested in small areas of an ERTS scene, 
to accept the grain size/pixel resolution limits, scale limi 
tations, and radiometric problems associated with standard ERTS 
photographic products. When requests to principal investigators 
for software assistance were not acknowledged, the author found 
it necessary to develop and apply an interactive computer pro 
cessing system using FORTRAN for enhancement and interpretation 
of ERTS raw. MSS data on Computer Compatible Tapes (CCT) , despite 
his limited programming experience. Of course, this work is re 
dundant with that of other investigators, with minor exceptions. 
However, it does demonstrate that users comparatively unsophisti 
cated in quantitative methods can apply these techniques to ad 
vantage, and that highly specialized, dedicated machinery is not 
a prerequisite to the efficiencies of interactive processing. 
In this context, the following paper is put forward, as a demon 
stration of what capabilities are inherent in the digital imagery, 
and require little in the way of expertise or expense to extract. 
THE INTERACTIVE SYSTEM 
The following is the core of an interactive (or batch) 
program package necessary for most users of ERTS imagery. 
"Window” creation 
Single band histogram 
Single band mapping