may reach unacceptable proportions. Therefore, in this case, a meaningful
statement of the restoration problem would be as follows: calculate ra(x, y)
so as to make
c(x,
y) as close to an impulse as possible subject to the con-
straint that the variance of the noise in the restored image does not exceed a
predetermined value.
A digital solution to the above problem was recently provided by Chu
and McGillem [16]. They have used the following measure of "narrow-
ness"
of the composite PSF,
c(x,
y):
r2
_
\™„$™
x
w(x,y)c
2
(x,y)dxdy
]
™
a0
^
a>
c
2
{x,y)dxdy
where the smaller the r
2
, the closer the
c(x,
y) is to an impulse ...
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