RE: [WM]: bior4.4 matlab function

["Dr. Fatih Kurugollu" <f.kurugollu@qub.ac.uk>]

Hi,

Your problem arises from the boundary extension process of the image to perform convolution filters in DWT to ensure the perfect
reconstruction.
Default extension mode in Matlab is half-point symmetric-padding extension.
If you change the extension scheme to periodic one using DWTMODE('per') you will get the smallest length decomposition which comply
with your expectation.

All the best,

Fatih



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Dr. Fatih KURUGOLLU

Lecturer

School of Electronics, Electrical and Computer Science Queen's University, Belfast

18 Malone Road, Belfast, BT7 1NN, UK

T: +44 (0) 28 9097 4628

+44 (0) 28 9097 1824

F:+44 (0) 28 9097 4879

E: f.kurugollu@qub.ac.uk

kurugol@yahoo.com

W: www.cs.qub.ac.uk/~f.kurugollu

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-----Original Message-----
From: watermarking-owner@watermarkingworld.org
[mailto:watermarking-owner@watermarkingworld.org] On Behalf Of Mostafa mohsen
Sent: Tuesday, March 06, 2007 8:59 PM
To: watermarking@watermarkingworld.org
Subject: [WM]: bior4.4 matlab function

hi watermarker

                     I tried to decompose 512 * 512 grayscale image using
bior4.4 matlab function by using wavedec2 function  but always get output of the corresponding bookkeeping matrix S as

>>[w s]=wavedec2(double(I),4,'bior4.4');
>>s =

          40    40
          40    40
          71    71
          134   134
          260   260
          512   512

But I expected  it to be in the form

  32    32
  32    32
  64    64
  128  128
  256  256
  512  512

I would be thankfull if any one tell me why the corresponding bookkeeping matrix S is equal the values i mentiones not the value i
expected

Mostafa


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