Selective glow ramps your glow at 3 different stages by configurable values this is to say we multiply your chosen color or the RGB value of your glow map by your configured values then by each other.
From this we can see that some colors will glow better than others; actually all colors will blur or "glow" all the same as the blur rates are independent of color however a bright glow should wash out to white.
If you use a true color such as 1,0,0,0.5 being red 50% opaque youll find that the inner and outer and screen intensity has a much lesser "washout" effect than if you chose for example 0.75,0.25,0.25,0.5 being reddish pink color 50% opaque.
Why does this happen?
Simply put multiplying by 0 always returns 0 that said the add of the inner and outer will pad the RGB value causing a washout at very high intensity values this way we are simply rendering a fuzzy red blob but odds are you intended the red shade to become lighter with intensity washing out the closer you get to point of glow ... to insure this effect isn't subdued unintentionally be sure you avoid max and min values for the RGB and A segments of your color and glow map
1,0,0,1 = pore quality
0.9,0.1,0.1,0.9 = better quality
0.75,0.25,0.25,0.75 = good quality
0.5,0.5,0.5,0.5 = max impact from intensity ... draw back no color this is a 50% opaque gray
Settings Performance vs Quality
You have a lot of settings available in Selective Glow and in general there is always more than one configuration to render a particular effect. Here is a simplification of how each setting impacts your performance and quality.
Lower numbers operate on more pixels but take more memory
Higher numbers operate on fewer pixels and thus lower resolution but take less memory
Lower numbers perform the blur operation fewer times thus fewer draw-calls but rougher results
High numbers perform more blur operations thus more draw-calls but smoother results
Modulates the iterations lower numbers yield tighter blur patterns while larger number give looser blur patterns. Performance impact is minimal but may effect GPU clock
This is simply the base factor the alpha is multiplied by before bliting to the screen; think of it as a global inner + outer intensity and has no notable effect on performance.
Inner Intensity & Outer Intensity
As with the image effects intensity this is simply the factor by which we multiply the map and color respectively and has no notable effect on performance.
Glow Map & Color
Color again is simply a factor to multiply by and has no notable impact on performance though Glow Map is a texture to be held in memory ... bigger textures take more memory but offer better detail. Remember this is a glow texture; we are going to blur it; odds are it doesn't need to be very big.