This module corrupts a Cimage with additive Gaussian noise
or with ``transmission noise''. 
\index{noise}

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With the \verb+-g+ option, a white Gaussian noise with standart deviation $std$
is added to each sample of the signal (see \verb+fnoise+ module for
more details on Gaussian noise).

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With the \verb+-t+ option, each sample is set to zero with probability
$t/100$.
