ASTROPHOTOGRAPHY PROCESSING

Stop light pollution spoiling your shots

- 

Improve your nebula images with a free gradient-removal tool

For astrophotographers, gradients are a common problem, even if photographing from a dark site. Caused by light pollution, either from artificial lighting or Moon glow, they make backgrounds look uneven and can particularly affect faint targets like nebulae. They can become more obvious when you stack your frames, detracting from fainter details. Thankfully, there are options to help.

Siril is a powerful, free processing program with a built-in gradient-removal tool called Background Extraction. It's best to remove gradients after stacking your image, before any stretching or processing. We'll therefore start with a freshly stacked image of the Rosette Nebula made from 105 sub-frames. If your stacked result shows artefacts on the edges, it's best to crop the image before using Background Extraction.