From help-request at octave dot org Tue Jul 19 03:15:11 2005
Subject: Re: Wiki Wavelab
From: Stefan van der Walt <stefan at sun dot ac dot za>
To: Ken Simpson <ken at MILitho dot COM>
Cc: help at octave dot org
Date: Tue, 19 Jul 2005 10:06:26 +0200

Hi Ken

On Mon, Jul 18, 2005 at 08:20:48PM -0500, Ken Simpson wrote:
> Hi - I've install Wavelab under Octave 2.1.70
> 
> 	http://wiki.octave.org/wiki.pl?WavelabOnOctave
> 
> and ran the following example (lifted from the above URL and modified 
> slightly)
> 
>   	octave:2> img = imread('/home/ken/images/lena256.jpg');
>   	octave:3> qmf = MakeONFilter('Symmlet',8); 
>   	octave:4> [n,J] = dyadlength(img); 
>   	octave:5> wc = FWT2_PO(img,J-1,qmf); 
>   	octave:5> imshow(wc) 
> 
> using the recommended fix for the reverse.m problem by P.Kienzle, 
> namely, 
> 
> 	dispatch("reverse","Wavelab_reverse","matrix");
> 
> It appeared to worked in the sense the forward transformation generated 
> the image I expecetd, however, when I attempted the inverse transformation 
> 
> 	octave:6> img = IWT2_PO(wc,J-1,qmf);
> 	octave:7> imshow(img) 
> 
> it appears to be executing the forward wavelet transform on img instead 
> of the inverse.
> 
> Has anyone else used this package? 
> 
> Am I doing the inverse transformation correctly? 

I've used the WaveLab package extensively with Octave.  Even the MEX
functions run correctly!  See the attached InstallMEX.m file.

The dispatch used on 'reverse' has nothing to do with the inverse
transform, though.  The example above works fine on my side.  You said
you modified it slightly -- what exactly did you change?

Regards
Stéfan



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