[WM]: Re: decomposing a image using filter banks

[Malapati Sekhar <malapatirs@yahoo.com>]

Dear Mathias,
 
Thanks for your fast and detailed reply. 
 
My doubt more elaborately:

 
I used DWTMODE('sym') which sets the DWT mode to symmetrization (boundary value replication). 
 
Kindly look at this site:
http://www.watermarkingworld.org/WMMLArchive/0307/msg00031.html
 
in the above site,
Dr. Barni mentions that (in his referring paper db6 filtering kernel as used) the increase in the number of pixels in level 4 (in
paper,  he counts from level 0 to 3)  is just one pixel.
But I am getting 10 pixels increased. (26, I got)
 
Where I am erroring while considering his statement?
 
Thank you,
Raja

Mathias Schlauweg  wrote:

Hi,

when using a filter with 6 taps (i.e. the Daubechies-6 filter) for computing the DWT every row and then every column is shifted
through this filter to get subband at resolution level 1. After that the columns and rows of this first subband are shifted through
the 6 tap filter to get resolution level 2 and so on ...
The pixel number your Daubechies-6 filtering kernel computed is correct.


Best Regards,
Mathias

----- Original Message -----
From: "Malapati Sekhar" 
To: 
Sent: Wednesday, November 03, 2004 1:00 PM
Subject: [WM]: decomposing a image using filter banks


> Hi,
>
> I used Daubechies-6 filtering kernel for computing the DWT.
>
> Consider example image : 256 by 256.
>
> After decomposing (level 4, db6), I got
> subbands at resolution level =1 of size: 133 subbands at resolution level 
> =2 of size: 72 subbands at resolution level =3 of size: 41
> subbands at resolution level =4 of size: 26
>
> Question: so now the number of pixels increased is 10 in the level 4 .. is 
> this correct??
>
> Thanks,
> Raja



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