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   -> Volume 2, Issue 6

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Author Message (Xuemei Chen)

PostPosted: Fri Nov 29, 2002 2:30 pm    
Subject: Question
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I used matlab to visualise the result of wavelet transform on a set of data
on a time-frequency plane. Basically I tried the function imagesc, with the
image gray levels representing the WT amplitudes. However I found no way to
control the axis scaling. I don't like the YDir to be inversed, and I would
prefer the origin to be (0, 0).
PCOLOR seems to satisfy these two requirments but I don't like its grid to be
shown. The image and pcolor both use built-in funcs.
So I have no way to control the output.

The automatic thresholding of these image utils is also a problem,
for which I can not compare the WT results of different data.

Could anybody who is implementing WT methods advise me as to a better visual
representation of the WT, references, publically available software, or solution
within the matlab? Thanks a lot!

-P.S. One way to see the amplitude for each level clearly is to plot
the amplitude along the time axis for each level. But this is not efficient as
I may need 10 such plot if I have 1024 data, which is hard to handle. Hence my
concern here is about a good method to represent all the information
that WT can provide in a complete and efficient way.

Xuemei Chen
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