StarTools stores the masks you used in your workflow in the StarTools.log file itself. This StarTools.log file is located in the same folder as the executables. The masks are encoded as BASE64 PNG images. To convert the BASE64 text into loadable PNG images, you can use any online (or offline) BASE64 converter tool.
The part to copy and paste, typically starts with;
One online tool for BASE64 is Motobit Software's BASE64 encoder/decoder.
To use it to convert StarTools masks back into importable PNG files;
This should result in a download of the mask as a PNG file which can be imported into the StarTools mask editor, as welll as other applications.
If we sample a large enough population of stars, we should find the average star color to be - likewise - white.
Their operation is intuitive; is there too much red in your image?
You can convert everything you see to a format you find convenient. Give it a try!