A friend of mine has a collection of
.jpg that cannot be opened because they start with
0xAD 0xE1 (so says GIMP).
Any idea which file format these may be?
It might be the FEE1DEAD code used by Linux reboot() syscall.
That is, on a machine with suitably swapped byte order, 0xAD 0xE1 might be read in that order
These definitely aren't jpg image formats or any common image format for that matter... I think a better question to ask is where your friend got these images or how he created them?