Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

Daubechies-4 wavelet transform in MATLAB

9 views
Skip to first unread message

Mariya

unread,
Apr 14, 2010, 5:04:46 PM4/14/10
to
Hello:

I have a 4x4 matrix which I wish to decompose into 4 frequency bands
(LL, HL, LH, HH where L=low, H=high) by using a one-level Daubechies-4
wavelet transform. As a result of the transform, each band should
contain 2x2 coefficients. How can I do this in MATLAB? I know that
MATLAB has dbaux and dbwavf functions. However, I'm not sure how to
use them and I also don't have the wavelet toolbox.

I have read the wikipedia article (http://en.wikipedia.org/wiki/
Daubechies_wavelet) and also this paper (http://www.springerlink.com/
content/57540u87733k1861/fulltext.pdf). I have no prior experience
necessary so any help is greatly appreciated.

Thanks.

Rune Allnor

unread,
Apr 14, 2010, 5:10:36 PM4/14/10
to
On 14 apr, 23:04, Mariya <mariya.nago...@gmail.com> wrote:
> Hello:
>
> I have a 4x4 matrix which I wish to decompose into 4 frequency bands
> (LL, HL, LH, HH where L=low, H=high) by using a one-level Daubechies-4
> wavelet transform. As a result of the transform, each band should
> contain 2x2 coefficients. How can I do this in MATLAB? I know that
> MATLAB has dbaux and dbwavf functions. However, I'm not sure how to
> use them and I also don't have the wavelet toolbox.

Well, both those functions are from the wavelet toolbox,
so getting that toolbox would be an obvious starting point.
Once you get it, there is a chance that there is some
documentation included, which might help explain how to
use the functions...

Rune

Dirk Bell

unread,
Apr 15, 2010, 1:49:21 PM4/15/10
to

That is an expensive answer if it is gotten legitimately.

Cheaper solution, web search.

Dirk

Rune Allnor

unread,
Apr 15, 2010, 2:05:30 PM4/15/10
to

I've heard some rumours that matlab has some safety features
built in, such that a function name from a toolbox you do
not have a lisence for somehow gets blocked. I haven't tested
it - don't even know if it is true - but this seems to be a
'reasonable' countermeasure against pirate versions of useful
functions. (Although it would be a nuisance for somebody who
might want to write a function with a name that happens to be
taken by a toolbox function.)

So if the OP wants to use those functions mentioned, getting
the toolbox seems to be the only option.

> Cheaper solution, web search.

Or learning the material from scratch and implement yourself.
But that was, of course, what you meant...?

Rune

Dirk Bell

unread,
Apr 15, 2010, 4:54:32 PM4/15/10
to
> Rune- Hide quoted text -
>
> - Show quoted text -

That is what I meant (I like to understand what I use, I have little
faith in unknown apps), but I guess realistically it may not be the
most efficient way.

Dirk

0 new messages