**Name**

**frthre** Thresold the pixel's gray-levels of a noisy fimage for optimal recovery

**Command Synopsis**

**frthre** [-l *noise*] *fimage* *result*

-lnoise: Absolute value of the additive noise

fimage: Input fimage

result: Output image

**Function Summary**

void frthre (A , B , noise )

Fimage A , B ;

float *noise ;

**Description**

*frthre* copies the input image *A* in the output *B* and makes a thresold
of the pixel's values according the rule:

`noise`

is the absolute maximal value of the noise (noise level).
In [DJ94], it is proved that this simple thresold rule is one
of the best estimator for recovering a noisy image (additive noise) using the MiniMax
error, when the coefficients in *A* and *B* are coordinates in an orthonormal basis
(such as wavelet basis).

**Version 1.0**

Last Modification date : Thu Nov 29 20:23:56 2001

**Author**

Jacques Froment