A good star mask is essential for good results. Though the Shrink module is much more gentle on structural detail than the basic unsophisticated morphological transformations (such as minimum filters) found in other software, ideally, only stars are treated and not any nebulosity, gaseous filaments or other structural detail.
The 'AutoMask' button launches a pop-up with access to two quick ways of creating a star mask. This same popup is shown upon first launch of the module. The generated masks tend to catch all major stars with very few false positives. If you also wish to include fainter, small stars in the mask, then more sophisticated techniques are recommended to avoid including other detail.
Besides touching up the mask by hand, it is also possible to combine the results of an aggressive auto-generated star mask (catching all faint stars), with a less aggressive auto-generated star mask (catching fewer faint stars, but also leaving structural detail alone);
Examples may be over-exposing star cores, dead or hot pixels, stacking artefacts, or other data defects.
This guide lets you create starless linear data using StarNet++ and the Heal module.
Upon launch, the colour module blinks the mask three times in the familiar way.
This preset also greatly reduces the green bias to minimise green, while attempting to bring out the popular golden hues.
If you wish to enhance S-II more visible in a Hubble-palette image, set this parameter to red (to which S-II should be mapped).
You can convert everything you see to a format you find convenient. Give it a try!