Author Topic: Combining Wavelet Planes  (Read 4577 times)

Offline Radar

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Combining Wavelet Planes
« on: 2005 July 05 11:07:40 »
Hi again Pteam,

When I am attempting noise reduction, by using the A Trous Wavelet Transform, is there a standard setting for Bias, Noise Reduction and Deringing? Or is it trial and error?

Also, when selecting certain Wavelet Planes, is it possible to reverse the colour of just one Wavelet Plane to see how it looks by itself? Or do Wavelet Planes have to be combined?

And, when combining Wavelet Planes to form a final image, should I just use pixel math? I use the add function on Pixel Match and simply drag the cursor over the original image to add the Wavelet plane, which seems to reduce noise. Sometimes, I add more than one Wavelet Plane at a time.

Is this the recommended way to do it?

Also, I notice that when adding Wavelet Planes to the Original Image, the color of the original image fades slightyly, should I just adjust the colors afterward combining, or is there a way to keep them to where they were?

And Finally, should both inverse check boxes in Pixel Math be ticked when adding Wavelet Planes to the original image?

I'm loving the software so far. The more I learn, the more fun it is.

Thanks very much for the software.

Ray
www.TheCosmicArtGallery.com
www.MyAstroSpace.com
C14, AstroPhysics 1600GTO, Coronado SolarMax90 DSII BF30, Sirius Dome.

Offline Carlos Milovic

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Combining Wavelet Planes
« Reply #1 on: 2005 July 05 14:18:07 »
Hi Radar!

>When I am attempting noise reduction, by using the A Trous Wavelet >Transform, is there a standard setting for Bias, Noise Reduction and >Deringing? Or is it trial and error?

Becouse each image is a different world, we strongly recommend a trial and error procedure to determine the best settings. Anyway, ussually more aggressive paramethers are almost always required by the smaller scales.

>Also, when selecting certain Wavelet Planes, is it possible to reverse the >colour of just one Wavelet Plane to see how it looks by itself? Or do >Wavelet Planes have to be combined?

There is a "Preview" checkbox at the right of the À Trous Waveles window. If you enables this mode, only the selected wavelet plane will be enabled. If you apply this to a preview or image, the result will show the contents of this plane, with inversed brightness.


>And, when combining Wavelet Planes to form a final image, should I just >use pixel math?

You may use PixelMath, but the ATrousWavelet process do the recombination process by itself. I'll explain this further.  If you just play with the paramethers avalaible in this window (bias, noise reduction, deringing, etc.), there is no need to extract the planes into several images. You are allowed to modify those paramethers for each layer independly, so if you apply the process with all the layers enabled, they are transformed and finally recombined to generate the resulting image.
By the other hand, if you do another kind of processing to individual wavelet planes (like morphological filters, convolutions, etc.), to recombine them PixelMath is the way to go.
If you just want to increase the weight of a given wavelet plane, i.e. adding it, just use the bias paramether.


>Also, I notice that when adding Wavelet Planes to the Original Image, the >color of the original image fades slightyly, should I just adjust the colors >afterward combining, or is there a way to keep them to where they were?

I highly recomend you to use the bias paramether instead of adding the wavelet planes manually. Also, if you just want to increase details (or decrease any structures), you may use the "luminance" option to preserve the color information.

>And Finally, should both inverse check boxes in Pixel Math be ticked >when adding Wavelet Planes to the original image?

It depends on what do you want to do. If you inverse the plane, and add it, it is exactly the same thing as substracting (inverting an image is equal to 1-value, in the normalizated range, and becouse PixelMath rescales the data, the 1 vanishes).
Again, I recommend you to use the bias paramether. Negative values decrease the weigt of the layer.

> I'm loving the software so far. The more I learn, the more fun it is.

Nice to heard this! Thanks for trying PixInsight LE and sharing your doubs and comments.
Regards,

Carlos Milovic F.
--------------------------------
PixInsight Project Developer
http://www.pixinsight.com

Offline Radar

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Combining Wavelet Planes
« Reply #2 on: 2005 July 08 03:01:19 »
Cheers for the support Carlos. That should keep me busy for a few days.

I'm going to post some before and after images on here to show my newly aquired digital processing skills off, and also maybe for some pointers.

Cheers

Ray aka Radar
www.TheCosmicArtGallery.com
www.MyAstroSpace.com
C14, AstroPhysics 1600GTO, Coronado SolarMax90 DSII BF30, Sirius Dome.