I’ve found that at least with the BCC+IR Color effect that taking the intensity negative inverts any mocha masks that are set. Said another way, you get the same result as when you check “invert mask”
In looking through the documentation all I could find for that parameter was “use to alter the intensity of the mask”
Is this mask inversion intended?
Yes, the mask inversion is intentional. It works roughly the same way in both the BCC and BCC+ filters. If the mask intensity goes to 0 it’s equivalent to turning off the PixelChooser, and if it goes negative it does wind up effectively inverting the mask. Probably not used a lot this way, but it’s been part of the PixelChooser design for ages.