Sometimes (perhaps always!) you can go back and take a second look at your images and get more out of them. At the very least it pays to save the stacked but unprocessed data, if not all the RAW images. In December 2015 I took what I thought were some very beautiful but rather sparse images of M42 and the Running Man nebulas in Orion. the nebulosity was mostly purple in colour.
Since then I have found out about ways of making the fainter parts of a nebula appear in an image, and also got better at balancing colour. This has enabled me to find the browner dust clouds in M42 while still controlling noise. Here's the reprocessed image, with a smaller version of the old one for comparison. Which do you prefer?
The 2016 reprocessing of older data for M42 and the Running Man (at top)