A stack of 22 images - sky conditions were poor with passing high clouds and light pollution (Bortle 4) and the lens used has quite a bit of vignetting, so stretching proved tough. A combination of Deep Sky Stacker (comet + stars mode, only light frames), Astro Pixel Processor (background removal), Photoshop (stretching, colours, and further noise removal) and Lightroom (some local adjustments) did the trick.