Topaz products that have to do with detail manipulation often have a peculiar setting labeled “Boost”, which is the source of some confusion among photographers.
“How is adjusting the Boost setting different than just adjusting the Strength setting?”
Adjusting the regular detail strength setting proportionally enhances all the details in the image. Adjusting the Boost setting disproportionally enhances the weaker details.
Basically, setting the boost higher means that the weaker and less contrasty details will be heavily enhanced. The weaker the details the heavier the enhancement on that detail. So while a strong and well-defined image detail will still be affected by the boost setting, the weaker details are affected a lot more. The opposite also holds true: setting the boost to a negative setting means that the weaker and less contrasty details will be disproportionally reduced.
On the other hand, the regular strength setting just linearly increases and decreases detail no matter how strong it is. This preserves the original relative detail strengths.
This is why the boost slider often seems to create a much heavier effect than the regular strength setting: giving all the less obvious details more definition can sometimes produce an overwhelming effect. Still, it’s useful to know what the Boost parameter is doing to your pixels.