**Name**

**precond1d** Preconditionning of an image

**Command Synopsis**

**precond1d** [-i] *Signal* *PrecSignal* *FicEdgeRi*

-i : Inverse preconditionning

Signal: Input signal

PrecSignal: Preconditionned signal

FicEdgeRi: Preconditionning matrices

**Function Summary**

void precond1d (Inverse , Signal , Output , Edge_Ri )

int *Inverse ;

Fsignal Signal ;

Fsignal Output ;

Fimage Edge_Ri ;

**Description**

*precond1d* performs the preconditionning (resp. unpreconditionning)
of the first and last coefficients of a univariate digitized signal,
before (resp. after) an orthogonal wavelet decomposition or reconstruction
with adapted filters for edge coefficients.
If the Daubechies wavelet used for the wavelet transform has cancellation degree *N*,
then the (un)preconditionning consists in applying an invertible linear transformation
to the first *N* and last *N* coefficients of the signal.

The sample values of the input signal are read in the file *Signal*.

The sample values of the output (un)preconditionned signal are stored in the file *PrecSignal*.

The coefficients of the preconditionning matrices or filters are read in the file *FicEdgeRi*. This file contains also the coefficients of the edge adapted filters for the wavelet decomposition.

The -i option specifies the inverse transformation.

**See Also**

**Version 1.01**

Last Modification date : Thu Nov 29 20:23:57 2001

**Author**

Jean-Pierre D'Ales