2000.05.23 20:12 "Re: Use of TIFFRGBAImageGet", by Frank Warmerdam

Can anyone please explain proper usage of TIFFRGBAImageGet to me? What I would like to do is read the image in in chunks, and have the library convert to standard 32-bit AGBR form (ideally RGBA, but that's another story).

>From http://www.libtiff.org/libtiff.html#TIFFRGBAImage, I get the impression that this is possible by repeatedly invoking TIFFRGBAImageGet within a TIFFRGBAImageBegin/End block. I do this, setting height to 1

TIFFRGBAImageGet(&img, raster, img.width, 1);

but this only seems to return the first line. I'd be grateful for any pointers.

Dylan,

Assuming you want to read the image in chunks, I would suggest using the TIFFReadRGBAStrip() or TIFFReadRGBATile() interfaces. If you want more detailed control, then I would suggest looking at their implementation in tif_getimage.c.

While I did implement these, I can't remember all the details involved. However I suspect you can only read in tile or strip sized chunks or something like that.

Good luck,

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