Astro Pixel Processor ("APP") is a paid stacking solution for Intel-based Windows, macOS and Linux OS's. Stacking and saving your data with these settings is essential to getting good results from StarTools.
In addition to the important pre-processing do's and don'ts, these are the settings in the APP tabs that need to be used to optimize datasets for StarTools;
If stacking multiple mono datasets for use in a composite, make sure to use one set's finished stack as a reference to stack the others with; StarTools's Compose module requires every dataset to be the same dimensions. Aligning remaining channels against an initial channel during stacking is particularly important to ensure consistency of point spread functions across channels; do not align finished stacks against each other after stacking.
Finally, do not pre-composite in APP, but use the Compose module in StarTools instead.
I'm relatively new to image processing and just wanted to say how straight forward and powerful StarTools is.
StarTools is famous for its Color Constancy color rendering.
Bin the image up until each pixel describes one unit of real detail.
As of 1.7, enhanced mouse controls are implemented; Zoom in.
Even the way StarTools displays and scales images, has been created specifically for astrophotography.
You can convert everything you see to a format you find convenient. Give it a try!