Technical specifications issues

In this section authors and participants can discuss about technical issues.

  • Evidence of lack of support for features that should be present in TIFF/A

    Paul Wheatley (Digital Preservation Coalition)'s picture
    Submitted by Paul Wheatley (... on September 15, 2015 - 4:31pm

    Based on discussions in the kick off meeting, the restrictions that TIFF/A might place on the construction of a TIFF file seem to be almost solely targetted at features or tags that might not be supported well in viewer software. Eg. multiple images per file, or JPEG compression.

  • What does it mean for a tag to have a 0 count?

    Nick Krabbenhoeft (New York Public Library)'s picture
    Submitted by Nick Krabbenhoe... on July 28, 2016 - 10:37pm

    I've come across a few TIFFs that libtiff flags a warning because the tag has a zero count.

    For example, this is an EXIFIFDOffset tag from a little endian file written by Photoshop 7 back in 2003
    6987 0400 00000000 00000000
    Imagemagick's convert passes the following warning from libtiff
    convert: Incorrect count for "EXIFIFDOffset"; tag ignored. `TIFFFetchNormalTag' @ warning/tiff.c/TIFFWarnings/891.

    When I tweak that tag to a fake private tag value
    6887 0400 00000000 00000000
    Imagemagick's convert passes the following error from libtiff

  • Overlapping tag data

    Gary McGath (mcgath.com)'s picture
    Submitted by Gary McGath (mc... on September 7, 2016 - 12:14pm

    I don't think I've seen this mentioned before. An issue with JHOVE is relevant to TI/A. The TIFF spec requires that "No data should be referenced from more than one place." That is, two different tags shouldn't point to the same data. I think this should be an explicit requirement of TI/A, since it isn't easy to notice and requires some special checking (which JHOVE hasn't done up to now). This may have been mentioned before. If so, sorry for committing the very violation I'm trying to avoid. :)

  • TI-A tag support

    Marisa Pfister (University of Basel)'s picture
    Submitted by Marisa Pfister ... on September 30, 2015 - 6:14pm

    I would like to come back to the point that Gary brought up in this comment,
    that the TIFF 6.0 Specification including the technical notes might be lacking some important tags.

    One of them is the ICC Profile.

    Another might be DateTimeOriginal, for example, but that could probably also be put in the image description or in a separate metadata file.

  • TIFF/A and CMYK

    Lukas Rosenthaler (University of Basel)'s picture
    Submitted by Lukas Rosenthal... on September 24, 2015 - 6:30pm

    One of the questions that bothers me at the moment: Should TIFF/A support/allow CMYK-images? How many of this kind of TIFF's are occuring in the memory institutions?

    I'm looking forward to Your insight on this topic!

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