Signs that can reveal a fake photo | Hacker News Reader

Signs that can reveal a fake photo

bbc.com

72 pointshvo18 comments

There's a YouTuber by the name of Captain Disillusion that has a series of debunking fake videos, using many of the same techniques described here.

Where it really gets cool is that he does video work for a living, and in many cases can even tell you what special effects and stock images from the software library were specifically used.

It's great stuff. Example: https://www.youtube.com/watch?v=rsXQInxxzBU

This is eye opening to see the tricks used all in getting you to give someone your money.

Regarding JPEG compression, there used to be a site that would make a heatmap of JPEG-induced noise for a given image, so you could see hotspots where it looked like it had been compressed twice (i.e. manipulated).

ELA? Error Level Analysis?

>ELA? Error Level Analysis?

Yeah, that was it. They shut it down but still have an info page on it: http://www.errorlevelanalysis.com/

It's easy to spoof if you try though, so it only works to detect unsophisticated forgeries.

That's the one I was thinking of, yes.

This one by any chance? https://29a.ch/photo-forensics/#forensic-magnifier

this is fun!

It's noteworthy that the first image in TFA doesn't have obvious signs of tampering in that tool

Great to read the government or other criminal groups in a BBC article!

It would be interesting if digital cameras would cryptographically sign photos. I'm sure there would be ways around that too (see also DRM arms race). Or at the very least use the photographer's private key to sign the photo. That might not prevent photo manipulation if the photographer wants to manipulate their photo but would prevent others from manipulating it.

Experts can still spot these clues -- for now. How much longer before better tools can create altered images/videos that correct for all these defects? Aligning shadows/reflections seems like something that software should be able to do.

I think that within the decade, photo/video "evidence" will be something that can be legitimately questioned unless there's some kind of cryptographic proof that it hasn't been altered. Cameras will need to "sign" their images, perhaps?

Canon (probably others) have "verification kits" for using digital photography as evidence. This is to verify images haven't been tweaked after the fact. Not sure exactly how it works, but canon at least seems to require the high end 1 series cameras, presumably signing the images..

from the press release: "The kit consists of a dedicated SM (secure mobile) card reader/writer and verification software. When the appropriate function (Personal Function 31) on the EOS-1D Mark II or EOS-1Ds is activated, a code based on the image contents is generated and appended to the image. When the image is viewed, the data verification software determines the code for the image and compares it with the attached code. If the image contents have been manipulated in any way, the codes will not match and the image cannot be verified as the original."

https://www.dpreview.com/articles/3146736527/canondvke2

Surely an easy work around would be to take the picture, doctor it, print it out, point the camera at the print out and snap.

Not sufficient; you will also need to worry about timestamps.

And with the printer resolution matching the camera

Check out Real-time Face Capture and Reenactment:

https://youtu.be/ohmajJTcpNk

This is surprisingly good stuff (for being a bbc.com article - they tend to be overly light on details).

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