I found an online tool that allows you to explore various color combinations for narrowband data. The tool combines Ha, SII, and OIII images using tri-color and bi-color palettes, making it easy to figure out which palette best suits your image.

Here’s a partial screenshot of the default image that’s loaded when you first visit the site:

There are six combinations in the screenshot, yet the tool produces a total of 24 combinations. You can use your own aligned Ha, SII, and OIII images as long as they are less than 2 MB each.

Here’s the link to the Online Narrowband RGB Combination Preview Tool.

This tool is a great addition to your narrowband workflow because you can easily compare color palettes all on one page.