Skip to content
Field Notes
Tools & AI
PixInsight Photoshop
Processing Guide
Astro Color Mixer: Professional Color Refinement in PixInsight
The Problem

You've finished your PixInsight processing. The image looks good—clean, well-stretched, properly balanced. But the colors? They're still flat. You find yourself exporting to Photoshop, Lightroom, or Luminar Neo just to add that final punch: richer blues in the nebulosity, deeper oranges in the core, more saturation where it matters.

This round trip costs you time and money (those external tools aren't cheap). And you lose the advantage of staying in your primary workflow.

The Solution

Astro Color Mixer—a script by Patrick Cosgrove that brings professional color-mapping directly into PixInsight. Adjust hue, saturation, and luminance by color band, with real-time preview, without ever leaving the application.

Why You Need This Script

Luminar Neo, Photoshop, and Lightroom all have a color mapper tool. It's consistently rated as one of their most useful features. But why export your finished PixInsight image to use it?

With Astro Color Mixer, you get the same power—tuned specifically for astrophotography—without the external software, without the cost, and without breaking your workflow.

Instant Comparison

Toggle between original and modified with a single click. See exactly what changes before you commit.

Color-Band Control

Adjust red, orange, yellow, green, cyan, blue, magenta independently. Or all together. Your choice.

Astrophotography-Tuned

Generic color tools oversaturate. This script respects subtle nebulosity and delivers natural results out of the box.

Fine-Grained Adjustments

Control saturation, hue, and luminance separately. Adjust color band width. Feather transitions. Full creative control.

Installation

Step 1: Add the Repository

In PixInsight, navigate to Resources → Updates → Manage Repositories.

Click Add.

Paste the Astro Color Mixer repository URL (available in the video description or on Patrick Cosgrove's GitHub).

Click OK.

Step 2: Check for Updates

Go to Resources → Updates → Check for Updates.

PixInsight will scan and find the Astro Color Mixer script.

Select it and choose Install.

Step 3: Restart PixInsight

Exit PixInsight completely, then restart.

The script is now ready to use. You'll find it under Script → Cosgrove's Cosmos → Astro Color Mixer.

This script works on all current PixInsight versions and even runs natively on Apple Silicon Macs—no emulation required.

Using the Script: The Basics

Launch the Astro Color Mixer from Script → Cosgrove's Cosmos → Astro Color Mixer.

You'll see three main control tabs:

Saturation

Boost or reduce saturation for each color band. This is where you add punch and make colors pop.

Hue

Shift colors within their band—move red toward orange or toward magenta, for example.

Luminance

Make colors brighter or darker without changing their saturation. Perfect for bringing out nebulosity or toning down bright cores.

Practical Workflow Example

Here's how to work with a galaxy like the Whirlpool (M51):

1 Open your processed image in PixInsight. Launch Astro Color Mixer. The script shows a live preview of your image.
2 Zoom in to the area you want to refine (2x zoom is often ideal). Click on a color region to tag it—the script highlights which color band is responsible.
3 Boost saturation on key colors. If orange in the core is too muted, select orange and increase saturation. You'll see the change in real time.
4 Toggle the preview (click and hold on the image, then release) to compare original vs. modified. Subtle is better than extreme.
5 Refine band width if needed. If your adjustment affects too much, increase the hue radius to narrow the band or feather the transition for smoother blending.
6 Adjust luminance to make colors shine without over-saturating. A small luminance boost on key colors often does more than large saturation increases.
7 Create new image or apply to target. New image leaves your original untouched; apply to target replaces it. Choose your preference.

Pro Tips

Sensitivity Matters

The default Normal sensitivity is conservative—perfect for astrophotography. If your edits feel too subtle, switch to Advanced for more aggressive adjustments.

But be careful: Advanced sensitivity can oversaturate quickly. Small adjustments go a long way.

Compare constantly. Toggle preview to ensure your changes read naturally, not garish.
Work in layers. Adjust one color band at a time. Save your work as you go.
Narrow your color bands if an adjustment affects unwanted regions. Use hue radius to isolate the exact color range you want.
Luminance adjustments are underrated. A 10-point luminance boost on blue can make nebulosity shine without aggressive saturation.
Test your changes on different zoom levels. What looks good zoomed in might be too strong at full canvas view, or vice versa.
Remember: you can always undo. Don't hesitate to experiment. The best way to learn color mapping is by doing.

Why This Beats the Alternative

Factor Luminar Neo / Photoshop Astro Color Mixer Cost $200–$600+ annually Free Workflow Export, edit, re-import Stay in PixInsight Astrophotography-Tuned Generic tools, oversaturate easily Built for deep-sky imaging Real-Time Preview Fast, but external window Instant, on your image Integration Separate application Native PixInsight script

The Bottom Line

If you've ever found yourself reaching for Photoshop or Luminar just to refine colors, Astro Color Mixer eliminates that friction. You get professional-grade color mapping—tuned for astrophotography—without leaving PixInsight, without paying extra, and without breaking your workflow.

The script is free, actively maintained, works on modern PixInsight versions (including Apple Silicon), and delivers subtle, natural results out of the box.

One fewer round trip. One more reason to stay in PixInsight.

Astro Color Mixer Guide by BrettjoAstro

Based on the excellent breakdown by Sasha from View into Space. Full credit to Patrick Cosgrove for the script.

Related notes

Tags: pixinsight colour script