Starguide - A Practical Guide to Astro-Photography

PixInsight

Working with Masks

updated: 2026-02-19

Purpose

Masking is used to protect specific regions or objects in an image from changes to brightness, saturation, etc.

There are several ways to create a mask, depending on what exactly needs to be protected in an image:

• a DSO object: see Creating a Lightness Mask
• a region in an image: see Free Hand Adaptive Mask (FAME)