**Name**

**precond2d** (Un)Preconditionning of an image

**Command Synopsis**

**precond2d** [-i] *Image* *PrecImage* *FicEdgeRi*

-i : Inverse preconditionning

Image: Input image

PrecImage: Preconditionned image

FicEdgeRi: Preconditionning matrices

**Function Summary**

void precond2d (Inverse , Image , Output , Edge_Ri )

int *Inverse ;

Fimage Image ;

Fimage Output ;

Fimage Edge_Ri ;

**Description**

*precond2d* performs the preconditionning (resp. unpreconditionning) of the first and last columns and lines of a digitized image, before (resp. after) an orthogonal wavelet decomposition or reconstruction
with adapted filters for edge coefficients.
This transformation is separable, i.e. the corresponding one-dimensional transform is applied successively to each line and each column of the image.
See *precond1d* module's documentation for a descripton of the one-dimensional algorithm.

The sample values of the input image are read in the file *Image*.

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

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