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1994.12.02 21:40 "Re: Appending images to an existing file", by Sam Leffler
To: tiff@sgihub.corp.sgi.com
Subject: Appending images to an existing file
Date: Fri, 02 Dec 1994 12:30:47 PST
From: "Venkatesh Narayanan" <venky@jayhawk.asd.sgi.com>
Hi,
I'm trying to append some images to an existing TIFF file that already has
an image in it. I'm not having much sucess doing this. Here is the sequence
of calls I'm making:
tiff = TIFFFOpen(filename, "r+"); //I've also tried "a" without success
TIFFSetField(tiff, TIFFTAG_IMAGEWIDTH, xsize);
TIFFSetField(tiff, TIFFTAG_IMAGELENGTH, ysize);
TIFFSetField(tiff, TIFFTAG_IMAGEDEPTH, 1);
TIFFSetField(tiff, TIFFTAG_BITSPERSAMPLE, bpp);
TIFFSetField(tiff, TIFFTAG_SAMPLEFORMAT, ttype);
TIFFSetField(tiff, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
TIFFSetField(tiff, TIFFTAG_ORIENTATION,ORIENTATION_TOPLEFT);
TIFFSetField(tiff, TIFFTAG_SAMPLESPERPIXEL, csize);
TIFFSetField(tiff, TIFFTAG_TILEWIDTH, xPageSize);
TIFFSetField(tiff, TIFFTAG_TILELENGTH, yPageSize);
TIFFSetField(tiff, TIFFTAG_TILEDEPTH, 1);
TIFFWriteDirectory(tiff);
TIFFSetDirectory(tiff, 1); //this always fails and I get the message :
//"Could not index into TIFF directory"
While(..there are tiles to write..)
TIFFWriteEncodedTile (tiff, tile, bufdata, bytecount);
Opening the file "r+" is not supported. If you want to append use "a".
I'm not sure what will happen with the above code. My guess is that the
TIFFWriteDirectory call will fail (though it should have generated a
diagnostic) and then the TIFFSetDirectory call will fail because,
presumably, you only have 1 IFD in the file.
Even if I take out the TIFFSetDirectory() call, what happens is that the
existing file has been corrupted and can't be read at all.
Anyone successfully appended images ? The README file says that the append
mode hasn't been tested.
Appending to a file works fine in v3.3beta021; you don't indicate
what version you have.
Sam