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.

# Daubechies-4 wavelet transform in MATLAB

Started by ●April 14, 2010

Reply by ●April 14, 20102010-04-14

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

Reply by ●April 15, 20102010-04-15

On Apr 14, 5:10�pm, Rune Allnor <all...@tele.ntnu.no> wrote:> 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... > > RuneThat is an expensive answer if it is gotten legitimately. Cheaper solution, web search. Dirk

Reply by ●April 15, 20102010-04-15

On 15 apr, 19:49, Dirk Bell <bellda2...@cox.net> wrote:> On Apr 14, 5:10�pm, Rune Allnor <all...@tele.ntnu.no> wrote: > > > > > > > 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 > > That is an expensive answer if it is gotten legitimately.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

Reply by ●April 15, 20102010-04-15

On Apr 15, 2:05�pm, Rune Allnor <all...@tele.ntnu.no> wrote:> On 15 apr, 19:49, Dirk Bell <bellda2...@cox.net> wrote: > > > > > > > On Apr 14, 5:10�pm, Rune Allnor <all...@tele.ntnu.no> wrote: > > > > 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 > > > That is an expensive answer if it is gotten legitimately. > > 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- 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