undefined | Better HN

0 pointsjoshspankit3y ago0 comments

> You can apply a filter and immediately after compute a hash.

Can you expand on that? I’m not sure what wouldn’t work

0 comments

3 comments · 2 top-level

>> For video, store the hash/phash of the frames with timestamps. But would that even work?

That would not work, because how do you prove that hash has been computed before video manipulation? Already, the imaging chips do some processing, so you never get the true raw image from the CMOS sensor.

joshspankitOP3y ago

Yes, I agree. I don’t think that method could be used if the manipulator was the person taking the photo or the one doing the initial processing. I’m (personally) less concerned about the true raw image vs lossy compression (i.e. JPG), and more concerned with things like the OP where an existing image was changed to show detainees smiling and that image was then used to manipulate the public.

The way it is now, it could easily have turned in to a “he said, she said” situation with each side claiming that their pic is the real one and the other’s was manipulated. In a case like that we could (theoretically) look back in the record to see which hash was recorded first.

EVa5I7bHFq9mnYK3y ago

>> For video, store the hash/phash of the frames with timestamps. But would that even work?

That would not work, because how do you prove that hash has been computed before video manipulation? Already, the imaging chips do some processing, so you never get the original raw image from the CMOS sensor.

j / k navigate · click thread line to collapse