Hello, post-truth world! More seriously, I think that digital photos, and especially low-res surveillance camera coverage, will soon be inadmissible in any reasonable court, because tools like this would allow to forge such evidence in very natural-looking ways.
There are probably ways to embed cryptographic hashes within images. Any device that creates images from the real world could have secret keys that can be used to validate any image created by said device. We will still need a centralized party that holds the secret keys for validation through
This is the right approach, but there’s lots of complexity around transcoding. In the courtroom that’s less of an issue if you can get the original unmodified outputs, but broader applications need to think through what it means to be “verified”