Ideally, rather than relying on a single synthetic PSF, multiple Point Spread Functions are provided instead, by means of carefully selected samples. These samples should take the form of. isolated stars on an even background that do not over expose, nor are too dim. Ideally, these samples are provided for all areas across the image, so that the module can analyse and model how the PSF changes from pixel-to-pixel for all areas of the image.
Coma or elongated stars towards one or more corners of the image.
The Color module is very powerful - offering capabilities surpassing most other software - yet it is simple to use.
You are forgiven if, at first glance, you get the impression StarTools offers only the basics.
Edges > Threshold; selects all pixels that are likely to belong to the edge of a feature.
You can convert everything you see to a format you find convenient. Give it a try!