GIMP, Reprocessing and C12 / NGC6946

Many thanks to Andy for posting his instructions for image processing – obviously caught the bug!

Its nice that someone else is also trying things out. The simple method there for reducing star trails had never occurred to me for example!

There are many different ways of achieving an objective once you have a general purpose toolbox, and often a combination of methods is the best option, The GIMP “pyastro” plugin is pretty good for rounding stars for instance, but doesn’t always work, especially when the stars are in front of an extended DSO.

That brings me to C12 / NGC6946. Rob has just posted a really good image of this. I posted one way back in 2015 (that is very poor compared to Rob’s) at

It suffers from all sorts of problems such as star trails and halos, so can we do anything about it?

I’ll not bore everyone by recounting the exact sequence of processing steps, as it will be different for every image.

Suffice it to say it was a combination of despeckle / star trail reduction / and dehaloing as I described here:

The dehalo method for deep sky objects using GIMP.

Anyway, here is the original as posted, and the reprocessed version.

Still not a patch on Rob’s, of course!

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