Hi Bob, would it be possible to share the submitted code, how the TIFF IFD and the EXIF IFD are handled. Are the error reported below from GraphicsMagick? How to reproduce this error? Then I could have a look.
Handling such "Customer IFDs" was always a tricky thing, because the TIFF IFD has to be written and re-read from file several times and IFDs have to be switched in the correct way, especially for multi-image TIFF. Some hints about that could be found in the comments of custom_dir_EXIF_231.c and at https://libtiff.gitlab.io/libtiff/functions/TIFFCustomDirectory.html And between 4.5.0 and 4.5.1 we speed up moving between IFDs for TIFF files having a huge number of IFDs (images) and handling of sub-IFDs. Regards Su -----Ursprüngliche Nachricht----- Von: Tiff [mailto:tiff-boun...@lists.osgeo.org] Im Auftrag von Bob Friesenhahn via Tiff Gesendet: Mittwoch, 20. Dezember 2023 23:07 An: Tiff List <tiff@lists.osgeo.org> Betreff: [Tiff] EXIF tag writing fails starting with libtiff 4.5.1? Recently a volunteer submitted code to GraphicsMagick's TIFF writer to create an EXIF subifd. When I tested this, it did not work for me. I was using latest libtiff from git. I did some investigating and found that the code works for libtiff 4.4.0 and 4.5.0 but fails starting with 4.5.1. Is anyone aware of changes which might cause the issue (or detect a problem which was not detected before)? The test case writes three identical images in order, each with an identical EXIF IFD. The final errors reported are: 15:49:49 0:0.005317 0.000u 2345878 tiff.c/AddExifFields/4510/Coder: Extracted tag from EXIF 11ah, Field 5, Long2 1, val 17895 XResolution 15:49:49 0:0.005443 0.000u 2345878 tiff.c/TIFFWriteErrors/975/Coder: Ignored: Error fetching directory link. (TIFFRewriteDirectory) 15:49:49 0:0.005476 0.000u 2345878 tiff.c/TIFFWriteErrors/975/Coder: Ignored: Error fetching directory link. (TIFFRewriteDirectory) 15:49:49 0:0.006473 0.000u 2345878 tiff.c/WriteTIFFImage/6687/Coder: Removed broken output file "input_truecolor.tiff" 15:49:49 0:0.006495 0.000u 2345878 constitute.c/WriteImage/2325/Coder: Returned from "TIFF" encoder, Failed ./utilities/gm convert: TIFF directory is missing required "ImageLength" field. (MissingRequired). Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ Public Key, http://www.simplesystems.org/users/bfriesen/public-key.txt _______________________________________________ Tiff mailing list Tiff@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/tiff _______________________________________________ Tiff mailing list Tiff@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/tiff
