This is part 4 in my first PixInsight Tutorial series of videos. In this fourth and final video in this series I will show you how to process the light frames for each filter in a non-linear stage. This will include how to remove the stars using StarNet2, how to do an SHO combination of the Ha, O-III and S-II light frames, how to create color masks and adjust the colors, how to reduce the greenish tint and magenta in the light frames, how to sharpen and remove some more noise from the image and finally how to add the stars back to the image. In the tutorial I will use a ASI294MM Pro camera and Ha, O-III and S-II filters, but the principles will apply to other scenarios. I will show you the complete steps for the entire processing in PixInsight.