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NANETH TIFFs

NANETH TIFFs. “TIFF stands for  Thousands of Incompatible File Formats ”. ...0000 0000 1 000 0000… …0000 0000 0 1 00 0000…. ...0000 0000 1 000 0000…. OR. …0000 0000 0 1 00 0000…. What does “valid” mean? . Well-formed? These images are! Verified by external tool? These images are!

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NANETH TIFFs

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  1. NANETHTIFFs “TIFF stands for Thousands of Incompatible File Formats”

  2. ...0000 0000 1000 0000… …0000 0000 0100 0000…

  3. ...0000 0000 1000 0000… OR …0000 0000 0100 0000…

  4. What does “valid” mean? • Well-formed? • These images are! • Verified by external tool? • These images are! • Confirmed as matching spec? • Who knows? • Internally consistent? • These images are definitely NOT!

  5. How do we detect it? $ exiftool -n -if '$FileSize# * 8 < $ImageWidth * $ImageHeight * $BitsPerSample' -p '$filename is TOO SMALL - $FileSize - ($ImageWidth*$ImageHeight*$BitsPerSample)' *.tif NL-HaNA_2.24.01.09_0_901-2649.tif is TOO SMALL - 9952834 - (3454*2877*16) NL-HaNA_2.24.01.09_0_901-2809.tif is TOO SMALL - 9952834 - (3454*2877*16) NL-HaNA_2.24.01.09_0_901-3431.tif is TOO SMALL - 9809944 - (2859*3425*16) NL-HaNA_2.24.01.09_0_901-4419.tif is TOO SMALL - 9807680 - (3425*2859*16) NL-HaNA_2.24.01.09_0_901-4451.tif is TOO SMALL - 9807680 - (3425*2859*16) NL-HaNA_2.24.01.09_0_901-5197.tif is TOO SMALL - 9809944 - (2859*3425*16) NL-HaNA_2.24.01.09_0_901-5556.tif is TOO SMALL - 9807680 - (3425*2859*16) BUT: As it stands, this only works on grayscale TIFFs

  6. How do we FIX it? $ exiftool -BitsPerSample=8 NL-HaNA_2.24.01.09_0_901-5556.tif AGAIN: As it stands, this only works on grayscale TIFFs

  7. What do we take away? • Don’t always assume your vendors/digitisers are doing the job right. • Don’t always assume that “successful validation” is meaningful. (Also: learn the limitations of your tools.) • The only thing better than double-checking is triple-checking. • KNOW WHAT YOU ARE “PRESERVING”!

  8. One last time…

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