2002.07.04 05:13 "Re: Photometric interpretation for grey-scale JPEG", by Tom Lane
Is this correct? If so, then should 6 be an acceptable PI for grey JPEG-in-TIFF?
Absolutely NOT, imho. 1 (MINISBLACK) is correct for grayscale JPEGs.
The fact that you came across some cluelessly encoded TIFFs is not grounds for breaking such basic assumptions as that PhotometricInterpretation has something to do with the colorspace of the stored data.
The only reason TTN#2 doesn't spell this out in so many words is that it never occurred to me that anyone might think otherwise.
regards, tom lane
organizer, Independent JPEG Group