2004.12.07 12:38 "Re: [Tiff] Fetching pixel data from 4bit tiff", by Dan Field
Hi. I'm new to libtiff and I'm no C guru either, so please excuse my ignorance here.
No just good old libtiff C library, I'm just rusty.
I am trying to get pixel data from a 4bit TIFF. I can use TIFFReadRGBAImage, TIFFReadR, TIFFReadG, TIFFReadB, TIFFReadA but surely these will not provide the correct data for a 4bit image?
Oh but yes, it should. TIFFReadRGBAImage always returns 32bit RGBA data, regardless of source colorspace and bitdepth. (Which is its greatest drawback, and its greatest convinience.)
Ah, excelent. I was starting to doubt my data. So if it converts from greyscale to RGBA, surely the R, G, B values would all be the same? eg
The data I'm pulling out doesn't fit this pattern at all:
R G B
71 202 94
14 209 94
213 215 94
156 222 94
99 229 94
Thanks for the fast response Joris :)
Dan Field <email@example.com> http://www.cymruarywe.org/
Developer / Sysadmin
Llyfyrgell Genedlaethol Cymru