Removing Green Chromatic Noise
Hasta La Vista... Green
There are hardly green objects in the nightsky, with only few exceptions such as comets, some planetary nebulae, aurorae… If we still find green hues in our astro images - after proper calibration, color-balancing and removal of possible gradients - we have to assume that it is probably chromatic noise.
Hasta La Vista Green (HLVG) is a chromatic noise reduction Photoshop plug-in, developed by Rogelio Bernal Andreo, to remove green noise and the green casts such noise may cause in some images. This tool is based on PixInsight's SCNR Average Neutral algorithm. (for the latter: check also Jim Delillo’s contribution to this TL-community Facebook page of February 11th)
I frequently use HVLG in my astro-image post-processing workflow in Photoshop CC. It is really easy to use with only 3 possible settings: strong, medium or weak chromatic noise reduction. If you use it together with layers & masks, you can further fine-tune your image as wished… (as always recommended with Photoshop or alternative photo-editing software).
The picture below, processed as an illustrative example, shows an RGB-image of the Orion Nebula before (left) and after (right) using HVLG, to "correct" the bluish-green hues in the original RGB-image of the Orion Nebula.
RGB-data from 3 one-click observations, captured with SPA-2 (Officina Stellare ProRC 700), was used.
You can find a free download of this HVLG Photoshop plug-in on:
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