The Wavelet Digest Homepage
Return to the homepage
Search the complete Wavelet Digest database
Help about the Wavelet Digest mailing list
About the Wavelet Digest
The Digest The Community
 Latest Issue  Back Issues  Events  Gallery
The Wavelet Digest
   -> Volume 5, Issue 9

Question: Help Using Non-Haar Wavelets in Code
images/spacer.gifimages/spacer.gif Reply into Digest
Previous :: Next  
Author Message (Bill Hoy)

PostPosted: Wed Oct 30, 1996 10:48 am    
Subject: Question: Help Using Non-Haar Wavelets in Code
Reply with quote

#25 Question: Help Using Non-Haar Wavelets in Code

For my research project at WPI, I am studying denoising methods using
wavelets. My advisor wanted me to write my own algorithms, so
starting with no previous knowledge of wavelets, I set out to learn
how to code the Discrete Wavelet Transform. After a few months of
work, I now can take the DWT of a signal using the Haar wavelet,
denoise it (threshold the DWT), and take the IDWT to see what I have
done to the original signal.

Since I was just starting with wavelets, I used the Haar wavelet. I
can understand how to get the two filter coefficients, use them on 2
input data points, and then slide it over 2 input data points and
repeat. This gives me the "halving" nature of using wavelets ( I see
the averaging and differencing feature).

I now would like to see if I could modify my existing Matlab code so
that I could use something better than a Haar wavelet. I have looked
at these wavelets, and I see that some have 4 or 6 coefficients. How
do I apply these 4 coefficients to my input array? I'm thinking that
I need to apply 4 input data points at a time to the 4 coefficients of
the wavelet. Do I then slide it over 4 points and repeat, or slide it
over 2 points and repeat (then there will be overlap)?

I realize my question is very-very basic and it shows my lack of experience
using wavelets! I've been having a hard time learning wavelets by myself!
Could anyone provide me with some ideas as to the above question, or
perhaps pointers where I could find some more articles for beginners? Is
it considered possible for a beginner to write their own DWT algorithms?
It would also be nice to hear from other people using wavelets to do


All times are GMT + 1 Hour
Page 1 of 1

Jump to: 

disclaimer -
Powered by phpBB

This page was created in 0.025486 seconds : 18 queries executed : GZIP compression disabled