Noise Reduction: Linear or Non-Linear

[jkmorse]

Got to sign on with Warhen here.  I now really only use MLT in the linear stage and TGVD in the non-linear phase for noise reduction.  With TGVD I like to use both a mask to protect to target and a lightness image, with boosted contrast, as local support, with a noise setting of 1.  You really need to experiment with the settings to get the right effect, but eventually you get great results.

Another thing that helps, especially if you are having issues with color artifacts, is to build a mask to protect everything but your background and then to desaturate the background using CurvesTransformation.  That may not be exactly "true" to the image data, but I'm not trying to show off the background.  Note you need to be really careful with this, or simply not use this technique, if you have lots of nebulosity, but for galaxies and clusters, it helps.

Best,

Jim

 

[iksose7]

Good tip Jim about TGVD there Jim, i'll be sure to give it a go. I've not tried TGVD yet due to reading countless times how hard it can be to get good results, but i've also read that if you get the parameters right it will give great NR! I'll play about with it on the image i'm processing now once i get to the non linear stage.

Callum

[Warhen]

JKM, yes- we're in agreement if you look back at my post.