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.

Using LibTiffDelphi?

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

R=45
G=45
B=45

The data I'm pulling out doesn't fit this pattern at all:

eg:

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 <dof@llgc.org.uk>            http://www.cymruarywe.org/
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