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2008.11.18 04:04 "Re: Creating a tiled tiff from scratch (essentially)", by Frank Warmerdam
Beck, Tucker A wrote:
> I am using libtiff in an image processing application. The input images are
> tiled, multi-image, JPEG compressed tiff files. I have had great success in
> opening, converting, and processing the image data using libtiff. Now, I
> need to be able to store the results of processing in a new tiff file. I
> have encountered a few problems along the way.
>
> When I create the tiff file, I would like to set up each directory when I
> create the file. I do not want to store any image data in them at creation,
> I just want them to be ready for writing data when it needs to be done.
> There are somewhere between 3 and 7 directories that I need to make. It
> seems like the only way to do this is to set all the fields for the
> directory, write a single dummy tile (using TIFFWriteTile) and then write
> the directory (TIFFWriteDirectory). This seems like an ugly way to do
> things; I'd rather not have to write any data until absolutely necessary.
> If I try to write the directory without having written a tile, I get a
> message that says, "MissingRequired: lib/op.svs: TIFF directory is missing
> required "TileOffsets" field." Is there any way to set up the directory
> with all the fields correctly assigned, but no data yet written?
Tucker,
Try calling TIFFWriteCheck() before calling TIFFWriteDirectory(). It sets the
"been writing" flag which appears to be necessary.
like:
TIFFWriteCheck( hTIFF, TIFFIsTiled(hTIFF), "GTiffDataset::Crystalize");
Note that you will produce a TIFF file with zeros for all the tile offsets.
Many applications will choke badly on such a file. So be cautious about
letting these files go into the wild in this state.
Best regards,
--
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com
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