NANETH TIFFs
description
Transcript of NANETH TIFFs
![Page 1: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/1.jpg)
NANETHTIFFs
“TIFF stands for Thousands of Incompatible File Formats”
![Page 2: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/2.jpg)
![Page 3: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/3.jpg)
![Page 4: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/4.jpg)
![Page 5: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/5.jpg)
...0000 0000 1000 0000…
…0000 0000 0100 0000…
![Page 6: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/6.jpg)
…0000 0000 0100 0000…
...0000 0000 1000 0000…
OR
![Page 7: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/7.jpg)
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!
![Page 8: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/8.jpg)
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
![Page 9: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/9.jpg)
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
![Page 10: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/10.jpg)
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”!
![Page 11: NANETH TIFFs](https://reader035.fdocuments.us/reader035/viewer/2022062314/56813af7550346895da382ac/html5/thumbnails/11.jpg)
One last time…