Restoration of a corrupted JPEG file

File contains JPEG data, so then it's always possible to glue on the header of a known good file that was shot with same device with settings matching as closely as possible (quality, resolution). If I do that I get this:

https://drive.google.com/file/d/1vWd0oXmqlcMOQ2CFmA9FQ2hZ0Cq0UHdd/view?usp=sharing

Note that the photo in above URL is edited because after 'gluing' on header photo looked 'washed' so I enhanced using Paint.NET.

So definitely not random junk. I only lost bottom 5% or so of the 6000x4000 JPEG. You can tell 'random junk' from JPEG data by looking at entropy and absence of certain byte combinations using a hex editor like HxD.

JPEG data is high entropy, compressed data, somewhere between 7.8 - 7.98 bits/byte. But ZIP files are high entropy too. So how to tell the difference? You can do this by using a hex editor like HxD: JPEG image data generally (unless the file contains restart markers) does not contain FF xx byte combinations unless xx = 00. So FF 00 is accepted by JPEG, FF A7 is not. FF 00 is decoded, FF A7 interpreted as a marker. Most decoders (image viewers) will either report invalid marker or simply stop decoding resulting in a partially grey image.

Indeed there's a smaller embedded JPEG inside. Also file starts with header-less JPEG data, then towards end of the file there's a header of another JPEG + 5% of image data. I used that header to decode the header-less image data at the start of the file.

I also created a video now that shows how I repaired this photo: https://youtu.be/nMpdPEKIPLU