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February 2004
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2004.02.23 14:50 "Re: Request for new functions", by Frank Warmerdam
Vladimir Pastukhov wrote:
> Hello,
>
> I'm adding Group3 and Group4 TIFF compression support to Python
> Imaging Library, using Libtiff codecs.
Vladimir,
I will leave this issue primarily to Andrey. However, I have a
few general questions:
1) Why not just implement all image access (on a block by block basis)
for PIL with libtiff? It seems to me there has been a longstanding
desire for a libtiff based PIL TIFF driver in addition to the existing
custom one.
2) If not building a fully libtiff based plugin, why not just adapt
the codec code you need from libtiff into the pil plugin instead of
using a full libtiff just for the codecs.
I guess my general concern is that libtiff wasn't really intended to be
a "codec engine" for applications that want to use the codecs in
isolation. In my own library (GDAL), I needed one of the codecs for
use with a non-TIFF format, but I found it easier to just copy and modify
the codec code I required.
> Because PIL can read image in chunks, calling appropriate decoder,
> it is necessary to save and restore TIFF codec's state.
Perhaps it is this chunking I don't understand. Lots of applications
want to read TIFF files in chunks, but libtiff generally requires them
to read a whole strip or block at a time, with a special case for line
by line reading I think.
Best regards,
--
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