Today I finally took the time to notice a new map type I never saw before called VrayBmpFilter. Now, I have to confess I have had no idea this existed, nor a clue what its for. It is not mentioned in the help either as far as I can see.
Anyone?
hmmm, new one on me too 
somehow missed that, thanks Natty
Aaahh…thanks.
(commences intense testing)
To be honest I cant really see any difference with or without. Maybe its not meant for max7.