PixInsight Scripts

PSF Guard hosts a PixInsight update repository at pixinsight.psf-guard.com. It currently publishes the Foraxx Palette Utility, a script that builds a Foraxx palette image from stretched, starless narrowband images, with an optional stars image. The scripts install and update through PixInsight's own update system.

Add the repository

In PixInsight, open Resources → Updates → Manage Repositories.
Add this repository URL, including the trailing slash:
```
https://pixinsight.psf-guard.com/
```
Run Resources → Updates → Check for Updates, accept the update, and restart PixInsight when asked.
The scripts appear under Script → PSF Guard Scripts.

The repository serves the current script to PixInsight 1.9.4 and later 1.9 releases, which run the new V8 JavaScript runtime. Installs from 1.8.9-3 through 1.9.3 receive the original 1.16 script instead. The packages are not code-signed, so PixInsight prints a warning in the console the first time a script runs. That is expected.

Foraxx Palette Utility

The Foraxx palette is a dynamic narrowband combination published by The Coldest Nights. Where a fixed mapping such as SHO puts each filter in one colour channel, Foraxx weights the red and green channels pixel by pixel from the OIII and Ha×OIII signal, which gives the bronze-and-teal look with fewer green casts. The script runs the PixelMath expressions for you and applies a standard set of curves and a selective saturation boost.

For SII, Ha and OIII the palette is:

o  = OIII^~OIII
ho = (Ha*OIII)^~(Ha*OIII)
R  = o*SII + ~o*Ha
G  = ho*Ha + ~ho*OIII
B  = OIII

where ~x is PixelMath's 1 - x. With Ha and OIII only, R = Ha. The stars image uses the same mapping with the star images in the colour terms, while the dynamic factors still come from the starless images.

Prepare the inputs

Stretch each narrowband master to non-linear. The script does not stretch.
Remove the stars from each stretched image with StarXTerminator or StarNet, keeping the stars-only image if you want a colour stars image.
Make sure every image has the same dimensions. The script checks this and refuses mismatched inputs.

Run the script

Open Script → PSF Guard Scripts → Foraxx Palette Utility.
Choose two channels for Ha + OIII data (mono, or OSC with a dual narrowband filter) or three channels for SII + Ha + OIII.
Pick a palette. Foraxx (dynamic) is the default; SHO, HOO, HSO and OHS are plain channel mappings for comparison.
Select the starless image for each channel and, if you want a stars image, the matching stars image.
Click Run. The console shows each step.

Options

Option	What it does
Channel gains	Multiplies each starless channel before combination, clipped at 1. Values above 1 push that channel forward; with Foraxx this also shifts the dynamic factors. Star images are not scaled.
Output identifier	The name of the result image. Defaults to the palette name. The stars image gets `_stars` and the combined image `_combined`. If a name is taken, a numeric suffix is added, so nothing is overwritten.
Create a stars image	Builds the colour stars image from the star images.
Combined image	Also screens the stars onto the result, `~(~result*~stars)`. Handy for a quick look; for a final image you will usually blend the stars yourself.
Factor images	Shows the `o` and `ho` factor images as separate grayscale images. They are informative only.
Standard adjustments	Applies the Foraxx curves and selective saturation boost to the result, and a curve to the stars. Uncheck to get the raw PixelMath output and do your own adjustments.

Options are remembered between runs. The reset button restores the defaults and keeps the selected images.

What you get

Foraxx: the palette image, RGB, in the sample format of the Ha image. Each adjustment is on the undo history, so you can step back to the raw combination.
Foraxx_stars: the colour stars image, if requested.
o and ho: the factor images, if requested.

From here, treat the result like any stretched image: blend the stars back in, adjust colour, and reduce noise as usual.

Updating and source

New versions arrive through Check for Updates. The script source, a headless test suite, and the packaging live at theatrus/foraxx-palette-utility. The repository index itself is built from theatrus/pixinsight-repository.

Credits

The original Foraxx Palette Utility was written and published by Paul Hancock (Paulyman Astro), copyright 2023-2024. The V8 rewrite for PixInsight 1.9.4, the extra palettes, gains and packaging are by Yann Ramin, copyright 2026. The palette and its expressions come from The Coldest Nights. This product is based on software from the PixInsight project, developed by Pleiades Astrophoto and its contributors.