The threshold THR in Background removal filter has the following effect:
- if alpha if between [THR - 0.1; THR], alpha is interpolated;
- if alpha >= THR, alpha is set to 1.0;
- if alpha <= THR - 0.1, alpha is set to 0.
It was introduced in order to smooth the alpha at the edges of the
foreground.
This works fine unless THR == 1, where there can be bulk pixels with
alpha which will be interpolated as if they were at the edge;
in order to ensure that a bulk area with alpha set to 1.0 is well
defined, the max threshold is now set to 0.95 (so if the user picks a
unity threshold, a value of 0.95 will actually be used).
This fixes a bug in third party plugins which rely on a bulk foreground
safely set at alpha == 1.0. [1]
[1] https://github.com/FiniteSingularity/obs-stroke-glow-shadow/issues/61
Signed-off-by: pkv <pkv@obsproject.com>
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