2006.12.05 15:52 "[Tiff] Grayscale, or is it?", by Joris Van Damme

2006.12.05 21:16 "Re: [Tiff] Grayscale, or is it?", by Edward Lam

So that's three out of three in favor of option 1), and confirming option 1) is common practice.

For the record, I don't use LibTiff's RGBA interface (ie. use TIFFReadEncodedStrip() or TIFFReadEncodedTile() instead) so I should probably abstain from voting. :)