AutoPaint- paint on /paint limit suggestion

Hello everyone,
How easy would it be to add on AutoPaint a limit only to certain values, and paint over time feature,
so for eg:
I select, limit effect/marks_made to a selection area made on a levels style histogram that can be set to luma or certain colour values, so we can set things to only paint ’ the bright red’ bits. ? We can play about with other filters and keys or whatever to get this eventually, but I think it would be a great benefit to have this ability right there and easy to implement if you wanted.

If that was possible, a paint on over time would be an additional bonus, if it was possible, eg fresh frames every frame for a jittery effect, through to never fade way( although I’m guessing with the way AE works this would get slow needing to go through every frame ? )
hope that makes sense?
Shane
edit- sorry , should be in sapphire forum

[Moved topic from Continuum Beta category to Silhouette Beta category]

I believe Shane is referring to Sapphire_AutoPaint filter and will move to Sapphire forum.