A MORE DISCRIMINATING USE OF AERIAL PHOTOGRAPHIC 
EMULSIONS AND PROCESSING TECHNIQUES 
Livio Fent 
Photographic Science 
Alberta Forestry, Lands and Wildlife 
Resource Information Branch 
Edmonton, Alberta, Canada 
ISPRS Commission VII 
ABSTRACT 
Aerial photographic emulsions have generally been classed into four 
broad classes: true color, color infrared, black and white 
panchromatic, and black and white infrared. A number of recent 
developments have expanded the film use spectrum so that users can 
now be more exacting and specific in their applications. The 
introduction of panchromatic-infrared films, a negative process for 
color infrared film, a greater diversity of color films, plus a 
greater awareness of average gradient-gamma manipulation have all 
contributed to a more discriminating user approach in aerial 
photography. A review of the benefits and applications of these 
technologies and techniques is undertaken. 
INTRODUCTION 
The past five to eight years 
have seen significant 
advancements made in the field 
of photographic emulsion 
technology. The introduction of 
tabular, core shell, so called 
"twin crystal" grains, and the 
application of DIR (developer 
inhibiting releasing) couplers 
have produced emulsions with 
improved granularity, 
resolution, and color 
saturation characteristics [1- 
4]. 
Aerial photography has also had 
its share of improvements in 
emulsion technology, partly as 
a result of the general 
improvements in the amateur- 
professional markets, and 
partly due to specific 
requirements in the process of 
vertical imaging. The effects 
of these changes has been two 
fold: one, end users of the 
imagery have become more aware 
and demanding of products 
which suit their needs, two, 
acquisition firms have had to 
adapt to the proliferation of 
these new products and also to 
the more critical demands of 
their clients. Although the 
situation has generally been 
advantageous to both the 
production and user sectors, 
some confusion has inevitably 
arisen regarding the 
appropriate application of the 
various film types. 
The four spectral class types 
of aerial films have 
traditionally been black and 
white panchromatic, black and 
white infrared, true color 
negative and positive, and 
false color infrared. These 
classes are still valid in the 
general sense, however, the 
profusion of newer films and 
more controlled processing 
techniques have introduced 
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