Two 'Mode' settings are available;
The Shrink module uses an iterative process; the strength of the Tighten or Dim effect is controlled by the number of 'Iterations', as well as the 'Regularization' parameter that dampens the effect. The stringing and pitting artefacts commonly produced by less sophisticated techniques, is thereby avoided.
The 'Color Taming' parameter forces stars to progressively adopt the colouring of their surroundings, like "chameleons".
The 'Halo Extend' parameter effectively grows the given mask temporarily, thereby including more of each star's surroundings.
If the image has been deconvolved or sharpened and the stars may be subject to subtle ringing artefacts, then the 'De-ringing' parameter will take this into account when shrinking the stellar profiles, as to not exacerbate the ringing.
The 'Un-glow' feature attempts to reduce the halos around bright, over-exposing stars. 'Un-glow Strength' throttles the strength of the effect. The 'Un-glow Kernel' specifies the width of the halos.
Through the Compose module, StarTools is able to process luminance and color information separately, yet simultaneously.
By using the advanced parameters, the Heal module can be made useful in a number of advanced scenarios.
The Heal module was created to provide a means of substituting unwanted pixels in an neutral way.
Understanding the former two important points will make clear why the various parameters exist in this module.
You can convert everything you see to a format you find convenient. Give it a try!