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Solving TIFF malformation using exiftool
Title
Valid and well-formed TIFF's with scanline corruption
Detailed description
The issue page
describes the problem as (essentially) TIFF files being unusable, despite being "validated" by tools like JHOVE.
Solution Champion
aamato
Corresponding Issue(s)
Relevant "issues" page.|http://wiki.opf-labs.org/display/SPR/Valid+and+well-formed+TIFF%27s+with+scanline+corruption]
Solution details
A lot of time was spent investigating the details of the file structure, for the images which could not be opened; which ultimately was a dead-end.
Eventually, we realised that the images were claiming to be 16-bit greyscale, but in fact, were actualy 8-bit greyscale. (Which, in retrospect, should have been more obvious, based on the rare error messages tools would give us.)
This meant that detection/correction suddenly became a lot easier: check for a discrepancy between image dimension and bit-depth, and the actual file size. (See below.) Similarly, because the pixel data was actually correct, we can correct the images by setting the correct value for the "BitsPerSample" tag.
- Important takeaways
- a
- b
Evaluation