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I went about depdup in a similar but opposite way then you did - https://github.com/mgolub2/photodb https://github.com/mgolub2/photodb I used libraw to read th

I went about depdup in a similar but opposite way then you did - https://github.com/mgolub2/photodb https://github.com/mgolub2/photodb I used libraw to read the actual raw data from my images, ignoring possible metadata that can get changed/updated by Capture One for example. The raw data is just fed into a hashing function, to get an exact content hash. Does not work if your image is down-sampled of course, but that was actually my goal - I want to know if the raw content has changed/bit flipped, but don't care if the metadata is altered or missing.

mceachen 3y ago
Ah! In this case, you might be happy to discover that ExifTool just added an "image content" hash--it's the SHA (or MD5 or whatever) hash of the _actual image bytes_, after ignoring the metadata header (and possible footer) payloads. So if you, say, change the rotation of your RAW image file (which normally will just add or change the EXIF `Orientation` tag), the image content hash will stay the same. See https://exiftool.org/ExifTool.html#ImageHashType https://exiftool.org/ExifTool.html#ImageHashType (of course, your current approach should prove substantively faster, but will only work with the formats that libraw supports)
- dcow 3y ago
  Why is GP's approach substantially faster?
  - mceachen 3y ago
    His tool is in rust, so he can directly call the libraw function. ExifTool is a perl tool, so it'd be an external process that he'd need to coordinate with.