1993.08.22 20:07 "Re: help on TIFFReadRGBAImage", by Sam Leffler
So the "(x,y)" in the sentence "Note that the raster is assume to be organized such that the pixel at location (x,y) is raster[y*width+x]" in the man page of TIFFReadRGBAImage refers to the 'normal' cartesian coordinates but not the (row,col) coordinate relative to the image, I suppose?
On rereading this I now understand the confusion. There is no mention of where the returned raster's origin is; it's in the lower-left hand corner. This call was designed for use with the SGI graphics library call lrectwrite.