As its name implies, the Pre-Process group includes controls that apply to the effect before the shine is applied. Think of it as tuning the variables that apply before turning on the light source.
Shine effects generally emanate from the most luminous areas of the image. Thus, in the context of Shine, the Threshold control establishes how luminous an area should be to receive the effect. Threshold sets the bar for the effect, if you will. A high Threshold setting means that only the image areas highest in luminosity will receive the Shine effect. The following images illustrate this using Blend Mode: Add.
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| Original | Threshold Zero |
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| Threshold Medium | Threshold High |
By default, Threshold is the only active control in this group. However, by enabling the Use Mask checkbox, you can establish a mask to isolate what part of the image will receive the Shine effect. The center of the mask is the Source Point (see this guide’s next page), the center of your light source.
Mask Radius sets the width of the mask’s hole, with 0.0 (the minimum) eliminating the hole and 500.0 (the maximum) potentially expanding the hole well beyond the image’s edges, effectively eliminating the mask.
Mask Feather establishes the softness of the mask’s hole edge. A lower Mask Feather value creates a “thinner,” graded mask edge, allowing more light to bleed through.
Threshold and the mask controls work in tandem. A Threshold of 255 will block all effect light, neutralizing any mask values. Similarly, a full-throttle Threshold won’t matter if your Mask Radius is set to 0.0. The three images below give a sense of the relative effects applied by Mask Radius and Mask Feather.
