Hi Ray,
Does this mean you need to use RAW files that are TIFF?
Yes.
I see from your previous post you are using VueScan; "raw" output from Vuescan is a tiff file - it simply means Vuescan has not made any adjustments at all - which is what is required for a profile target scan.
See attached for my VueScan Input & Output settings, as recommended by PP Help.
NB. our scanner may not be capable of multi passes to ignore that setting which is optional.
Terry