from the original signal is applied to a double logarithmic 
amplifier which provides the dynamic compression (fig. 3). 
A 
DN, RA A t |! Lp rfr 
- SE K NL Nos | Hu M ! lu e ! n 
A N nd Ws E AM ns RE e DOSE PARET 7 
vh 1] ul nig sts Eu t vs 
Fo, TET PRG 
video signal extraction of high logarithmic ! logarithmic 
from scanner "| frequency component , | compression j————, compression  ;— to the printer 
ight no. | | | I^ step | | I1” step 
g 5 L - v Lt — a KL ZZ 
Fig. 3. Block-diagram for the harmonic analysis performance. 
B . . 4 t 
Moreover, to have a texture description as accurate as possible 
among the number of different components forming the video sig- 
nal, which is selected with wave frequency close to the maximum 
instrumental resolution (100 KHz in our case). 
Description of thermal behaviour 
By comparing the series of images from the initial analy- 
A sis, one can easily see the presence of thermal inversion phe- 
nomena caused by the various environmental conditions before 
sunrise and the subsequent heating. The body of water whose 
temperature seems to be constant, influences only those areas 
; of land rising little above the sea level. In our case the in- 
[ene no. o vestigated area, vith a morphology only slightly modified by 
man's direct intervention, it traversed in its central section 
by a long, natural canal which forks into diverse branches of 
minor importance and varying depth. 
B The islands present contain beds of water with a control- 
led flow of water, "Valli da Pesca" (fishing marshes), and shal 
low water zones (marshes) surrounded by "hummock" (areas cover- 
ed with vegetation submerged only during high tide). 
The comparison of the thermographs shows us exactly that 
for emerged areas, the inversion begins around 9 A.M. (see the 
island of Santa Cristina); the land becomes warmer than the