Where to find specifics about the Gamma Map Speckle Filter?

Hi Radar Geeks,
I need specifics about the Gamma Map Speckle Filter, I didn’t find anything in the help.

I did a Gamma Map 3x3, “Estimate Equivalent number of Looks” is ticked. (on a Sentinel-1 scene)
I now want to describe the specifics in a paper.

I found in the processing node metadata:
1 Filter: Gamma Map
2 enl: 1.0
3 windowsSize: 7x7
4 anSize 50
5 FilterSizeY: 3
6 targetWindowSizeStr.: 3x3
7 filterSizeX: 3
8 sigmaStr. 0.9
9 numlooksStr.1
10 dampingFactor 2
11 estimateENL: true

1,2,5,7,9,11 are very understandable
the rest gives me some headaches:
actually, 6 would be very important, does 3x3 mean that:
a) 9 pixels
b) 8 pixels
c) 5 pixels
d) 4 pixels
are used to calculate the new pixel?

Also, why 7x7 when I choose 3x3? And what is anSize 50?

Any hints would be highly appreciated, also where to look (source code would be an option, but I know from experience it is sometimes hard to read). The issue is important to me.
Cheers, Christoph

For Gamma Map filter, only the following parameters are used:
Filter Size X
Filter Size Y
Estimate ENL

The other parameters are for other filters. For example, Damping Factor is for Frost filter, Target Window Size for Lee Sigma filter.

3x3 means 9 pixels

Wow, thank you so much for your reply. :+1: :pray: :fist_left:

Is there any reason why the shape of the image is altered? I have performed a Speckle Filtering using Gamma Map and found out that the resulting image has a different count of rows and columns. The window used was a 5x5 with default ENL.