PixInsight is a powerful image processing package that I've been using lately for my astro images. There is a lot of tutorial and other helpful PixInsight material on the PixInsight site and elsewhere on the web, but it's sometimes hard to locate specific items.
Here's a list of links to useful items that I've discovered. Each link opens in a new page, and of course all the material belongs to the original authors. I also have another page of links organized by topic, available here.
Video Tutorials
Harry's PixInsight Video Tutorials - A comprehensive series of PixInsight Tutorials from Harry Page
Balancing the Histogram - YouTube video from RBAF
Mosaic Construction with Star Alignment - YouTube video from PixInsight
HDR Composition - YouTube video from PixInsight
Introduction to DBE, ACDNR, and HDR Wavelets - Videos by Juan Conejero, PixInsight
The Screen Transfer Function - from Craig Stark at Stark Labs
Preview Windows - Craig Stark
Automatic Background Extraction - Craig Stark
Dynamic Profile Module - YouTube video demonstration by its author, Sander Pool
Web Page Tutorials and Presentations
Master Calibration Frames: Acquisition and Processing - by Vicent Peris, PixInsight
PixelMath Reference - by Juan Conejero, PixInsight
Noise Reduction in Astronomical Images using ACDNR - by Thomas W. Earle
Noise Reduction with ACDNR - by Juan Conejero, PixInsight
Processing a Ha CCD Image - by Daniel Bosch, on the PI Website
Image Integration Techniques - A downloadable presentation by Jordi Gallego
Luminance Processing - by Rogelio Bernal Andreo
HDR Composition - by Rogelio Bernal Andreo
Multi-Scale Processing - by Regelio Bernal Andreo
Removing Gradients - by Rogelio Bernal Andreo
A New User's Experience - PixInsight Workflow from Dogwood Ridge Observatory
Descriptive Material
New Project Functionality in PixInsight 1.7 - YouTube video from PixInsight
Useful Forum Posts
Background Noise Reduction - Scroll down through this posting for a very useful tutorial on ATWT from Juan Conejero
Morphological Transform - An illustrated example on Cloudy Nights from Michael Fulbright
Moving Data from CCDStack to PixInsight - A Cloudy Nights discussion
Dynamic PSF - The new Point Spread Function, described by Juan
HDR Composition - The new HDR tool, described by Juan
Deconvolution - Another of Juan's great little tutorials, on the PI Forum
LRGB Combination - A good discussion of how to properly combine LRGB frames
Mosaic Construction - A useful forum thread, with a link to the Mosaic Video Tutorials on the PI Site
Other Material
The Officially Unofficial Reference Guide from Rogelio Bernal Andreo
Harry's PixInsight User Guide - Illustrated descriptions of many PixInsight tools. Not to be confused with Harry's great PixInsight Videos, which are linked above
PixInsight LE Documentation - Although PixInsight LE is obsolete, there is still a lot of useful information in these online Help files
PixInsight Magazine - A new PDF magazine from PixInsight