Open PixelMath and write the following expression. To do this use DynamicBackgroundExtractor if gradients are present, then use PixelMath to set all the backgrounds to the same level: create a small preview containing only background, drag its tab on the PixInsight Working area to create a new image and rename it to BG. The starting images should be perfectly registered, gradient free and, possibly, with the same background level. Hereafter Ha will be the master Hα image: Oiii the master OIII image and Sii the master SII, all at linear stage. On a TS 80 Q refractor under a suburban sky. The data set used for this tutorial consists in images of the Mexico Gulf in NGC 7000 taken with a SBIG ST2000XM camera equipped with a Baader filter set: The original Metsavainio method is based on Photoshop I will try to translate the workflow in PixInsight with only a few differences. Using starless copies allows boosting faint channels without worrying about stars moreover the noisy OIII and SII channels can be strongly denoised as they will be used only for chrominance: all the details will be in the enhanced Hα luminance. To overcome this problem J-P Metsavainio has developed a technique based on tone maps, starless copies of the original narrowband channels, and an enhanced luminance based on Hα image modified with OIII and SII tone maps. The drawback of this composition is that, since Hα widely dominates on OIII and SII emission, OIII and SII image histograms should be boosted relative to Hα, this bloats stars and creates weird magenta halos. In this composition the SII emission is associated to Red, OII to Blue and H alpha to Green. One of the most famous color composition technique of narrowband data is the Hubble Palette that gives to nebulas a typical golden-turquoise color palette. Recently I began to take astronomical pictures in narrow band using my SBIG ST2000XM and a set of Baader Filters (Hα, Hb, OIII and SII).

Pixinsight 1.8 download