This module performs a ``phase randomization'' on a Fimage, defined by
$$u' = F^{-1} \{ |F \{ u \} | e^{i \phi} \} ,$$
where $F \{u\}$ means the Fourier Transform of $u$, and $\phi$ is an
antisymetric field of random independant variables uniformely distributed
on $[0,2\pi[$.
In addition to that, a gain-offset correction is finally applied on $u'$ 
in order to keep the $u$'s original mean and variance.
\index{Fourier Transform}

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This operator can be viewed as a ``texturization'', since it is well-known
that microscopic textures can be caracterized by their correlation function
$$\Gamma_u(x) = <u(t)u(t+x)>_t,$$
which Fourier Transform equals $| F \{ u \} | ^2$ up to a multiplicative 
coefficient (Wiener-Kichnine theorem). Thus, this function is a kind of 
projection on the space of microscopic textures.
\index{texture}

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The random seed used ({\sf drand48}) is reinitialized with the current time
plus the process id unless the -i option is set.

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NB: Calling this C-subroutine with $out=in$ is possible 
