Stretching for Bill Blanshan’s narrowband normalisation tool - Forums

Topic starter

Oct 27, 2023

Hi All.

I use a OSC camera and find Bill’s narrowband normalisation tool really useful for creating images in the HOO palette. However, it’s recommended not to colour calibrate beforehand. Normally I use Bill’s “Unlinked HT Stretch” tool before narrowband normalisation but I’ve been learning GHS and would like to start using GHS to stretch. However, if I don’t colour calibrate, I just get a green overlay when using GHS due to the RGGB bayer pattern.

Do those of you who use narrowband normalisation stretch via GHS and if so, how do you overcome this issue?

Thanks.

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TurtleCat

Oct 28, 2023

My typical procedure, and it's worked great for me, is to run SPCC and DBE before I do NarrowbandNormalization. I only use Mode 2 for HOO since I'm using the L-Ultimate dual band. I believe on the PixInsight forum that was the only recommended option for a dual band setup. I may try it without color calibrating. I'll load up an image I have handy and see if it looks any different. I just looked and it looked the same to me.

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TurtleCat

Oct 28, 2023 · Edited: Oct 28, 2023

Now in both of those cases, I should add, I did background extraction before running SPCC and/or NN which takes care of the green bias.

Craig Dixon

Topic starter

Oct 29, 2023

Thanks, that’s really helpful. I’ll try this on some data today.

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Craig Dixon

Topic starter

Nov 3, 2023

I've had a go at using SPCC and then GHS but I can't get the narrowband normalisation tool to work as expected using this method. I'm still getting far better results by just using Bill's "unlinked stretch" tool.

TurtleCat

Nov 3, 2023

I would do GHS after you’ve done NN. It’s much better used before any stretching IMO.

Danny Lee

Nov 3, 2023

I had the same issue, narrowband normalisation (NN) works best on an unlinked stretch but stretching with GHS first didn't produce good results with NN.

You could try a combination and as Turtlecat has said, try applying a light unlinked STF or Bill's stretch, run NN and you can then try and get a bit more with GHS after narrowband normalisation.

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Craig Dixon

Topic starter

Nov 5, 2023

I didn’t realise I could use NN before stretching so thanks for that. I’ll try on the next image I process.