Brightness Trigger defines the threshold value, which must be exceeded before a flare appears. The value is defined as a sum of red, green and blue. A pure white color has brightness 3.0 and pure red has brightness 1.0, etc.
Max Flare Count defines the maximum number of flares added to the image. Only the defined amount of brightest areas will get the flare. This is the maximum amount, not the exact amount. If the picture is too dark, no flares will be added.
Trigger Channel selects the channel which triggers flares. Usually it can be the color channel.
The lower part of the image flare properties window contains the standard lens flare gadget. See the description of the Lens Flare effect for details.
The effect can extract highlight areas better, if you use 'Illumination' as the trigger channel. 'Illumination' value range is not clipped to 0..1 and its default data type is 'Word'. A byte can only represent a brightness scale from black = 0 to white = 1, whereas 'Word' channels can store values from zero up to 16. In other words, there are plenty of brightness values after white, and the program can locate the maximum brightness spots better.
|Do not use box rendering with the image flare effect, or apply image flare as an effect for full images. Render boxes break continuous bright areas and flare computations become inconsistent between boxes.|