Pre-Process
In the Pre-Process group are the functions that can be applied before the actual shine is applied, including threshold and masking options.

Threshold is used to isolate the brighter areas of the image and let only them be affected by the plug-in. (Transfer Mode Add is used in these illustration images)

Original image | Threshold Zero
Threshold Medium | Threshold High

Use Mask is used to isolate a circular area around the Source Point and let only that area be affected by the plug in. The settings are Radius and Feather (both in pixels).

Mask Off | Mask On