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December 2004
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2004.12.07 11:38 "Re: 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/ http://www.walesontheweb.org/ Developer / Sysadmin Llyfyrgell Genedlaethol Cymru