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Re: [PanoToolsNG] incompletely uploaded jpeg and tiff in FTP - how to detect?

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  • Roger Howard
    Yeah, there are a number of ways, depending on the upload process - 1. If you control the uploader tool (probably don t) then you can calculate a checksum and
    Message 1 of 4 , May 1 10:47 AM
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      Yeah, there are a number of ways, depending on the upload process -

      1. If you control the uploader tool (probably don't) then you can calculate
      a checksum and compare to the uploaded file's checksum... or even just a
      filesize compare
      2. Use one of a number of tools that will check the consistency of the
      formatting - this won't necessarily prove the upload was incomplete... it
      could have been damaged prior to upload - but is a good idea any time
      you're accepting media files anyway.

      Some ideas:

      exiftool - though not built for this, it's pretty good about error
      reporting
      libjpeg and libtiff both have a variety of tools which will report errors
      on parsing those formats - likewise, many tools based on these libraries
      (for instance, ImageMagick) will report errors back up to the user based on
      parsing problems encountered in the library
      jhove - a much more robust/complex tool, but designed for
      validating/profiling a wide range of file formats

      3. If you want something really simple:

      for jpeg: check that the file ends with "FFD9" (in hex) - the only time
      that sequence should appear in a JPEG is at the very end
      for tiff: check that the file ends with "0000" (in hex) - it's not an "end
      of file" marker technically, but, I believe, all TIFFs should end with it
      IIRC; of course it's quite possible for a TIFF to contain "0000" elsewhere
      in the file, so this isn't a guarantee - but if the file DOESN'T end with
      0000 you can be sure it's incomplete.
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