tion. In geothermal areas this operation is particularv 
meaningful. 
3 Ratio between thermal channels. 
In this way a relative emissivity map is obtained (Fig. 10). 
The captions of the images related to the above examples 
will give detailed information on the applications of this 
techniques. 
AKNOWLEDGEMENTS 
The authors recognize the valuable assistance of Dr. 
G. Platania of Rossi Ent-Italv, during the play-back opera 
tions . 
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