Hello,
I've been working on sorting & storing a large number of images and have run into something without an obvious explanation. sha512 was used to distinguish file uniqueness.
Things got weird during verification: I found numerous JPEGs (177 pairs in sample) where the files are otherwise identical in hexdump except for a single bit at the 19KB mark:
< 0004c20 0000 0000 3130 3030 0000 0064 047b 0000
---
> 0004c20 0000 0000 3130 3030 0001 0064 047b 0000
Which leads to some questions for those who know far more about Nikon's EXIF than I:
- Is it true Nikon only stores EXIF in the first 64KB?
- If so, can I just ignore the first 64KB to get a useful uniqueness test?
- What could have changed this? My initial thought was "bit rot," but this is too consistent and narrow.
For what it's worth, "047b" is two less than the reported ShutterCount. This suggests the bit difference is somewhere in EXIF (probably?) but I haven't a clue how it changed.
Thanks,
-Jon
Hi Jon,
Without any context I can't say what bit this is.
Try using the ExifTool -html dump feature to analyze the metadata. This may help answer your questions.
- Phil