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#### Image Denoising by Wavelet #2

```what is the actual meaning of the 1st parameter in the method WDENCMP() in MATLAB and how do i calculate the value of the 5th parameter i.e., THR of this method?

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Ajit
4/15/2010 6:11:03 AM
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```"Ajit " <ajits321@gmail.com> wrote in message <hq6aln\$4bf\$1@fred.mathworks.com>...
> what is the actual meaning of the 1st parameter in the method WDENCMP() in MATLAB and how do i calculate the value of the 5th parameter i.e., THR of this method?
>

Hi Ajit, The option 'gbl', uses a global threshold that is applied to all levels of the wavelet transform. 'lvd' allows you to specify level-dependent thresholds, which you supply as an input to wdencmp(). If you specify level dependent thresholds for an image, they have to be in the form 3xN, where N is the level of the decomposition. The row dimension (3) is for the horizontal, diagonal, and vertical detail coefficients respectively.

As a first pass, just try using the global threshold returned by ddencmp()

Just an example:

X = randn(256,256);
[thr,sorh,keepap]=ddencmp('den','wv',X);
[XC,CXC,LXC,PERF0,PERFL2] = ...
wdencmp('gbl',X,'sym4',4,thr,'s',1);

Hope that helps,
Wayne
```
 0
Wayne
4/15/2010 10:22:06 AM