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Signs that can reveal a fake photo (2017)

bbc.com

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Re: Signs that can reveal a fake photo (2017)

#21

Post by hdm41bc »

kc0bfv wrote: post #16
hdm41bc wrote: post #14

Is this a solvable problem by requiring camera manufacturers cryptographically sign photos and videos created on those devices? If that’s in place then it seems like it could be the basis for chain of custody of journalistic images backed by a blockchain. This seems like the only viable solution to me since any AI powered solution would just be a cat and mouse game.

In this scenario, it would almost certainly have to be that manufacturers would have to build cameras that cryptographically sign the images and videos. The cameras would have to be able to have that ability, install of the manufacturers doing the signing. And then what would the Blockchain provide in this case? A chain of cryptographically signed certificates back to a manufacturer is basically the same system we us…

The way I thought that the blockchain would be employed is to use it to track transformations of the image. Post-processing, adding captions, and what not. This would provide an audit trail of changes to the original source image.

If, in fact, we can’t reliably sign the source image as authentic, then the rest of the system falls apart. It seems like this is the crux of the problem.

Re: Signs that can reveal a fake photo (2017)

#22

Post by kkielhofner »

hdm41bc wrote: post #14

Is this a solvable problem by requiring camera manufacturers cryptographically sign photos and videos created on those devices? If that’s in place then it seems like it could be the basis for chain of custody of journalistic images backed by a blockchain. This seems like the only viable solution to me since any AI powered solution would just be a cat and mouse game.

Exactly. In fact, that's the approach[0] taken by my new startup.

[0] https://www.tovera.com/tech

Re: Signs that can reveal a fake photo (2017)

#23

Post by dang »

hwers wrote: post #2

I wonder why the article has the title '20170629-the-hidden-signs-that-can...' in the url. That date would suggest it's from the 29th of june 2017 (while the date below the headlines says 2020), way before the current breakthroughs of deep fakes.

We've added the year to the title now. Thanks!

Re: Signs that can reveal a fake photo (2017)

#25

Post by dang »

hwers wrote: post #4
commoner wrote: post #3

Earlier quoted context omitted.

Nice catch. The article was republished. Here's an archive from 2019 of the original 2017 version: https://web.archive.org/web/20191030232152/https://www.bbc.c...

I'll be honest and admit that in taking a second look I noticed that they totally admit to this being a republished article from earlier: " [...] BBC Future has brought you in-depth and rigorous stories to help you navigate the current pandemic, but we know that’s not all you want to read. So now we’re dedicating a series to help you escape. We’ll be revisiting our most popular features from the last three years in o…

Still kind of dodgy not to include the original date, and to display today's date in exactly the same way that a publication date is usually displayed.

Re: Signs that can reveal a fake photo (2017)

#26

Post by kc0bfv »

kkielhofner wrote: post #15

It's been really interesting to see another recent uptick in media (and HN) coverage of deepfakes, modified media, etc lately. There are virtually endless ways to generate ("deepfake") or otherwise modify media. I'm convinced that we're (at most) a couple advancements of software and hardware away from anyone being able to generate or otherwise modify media to the point where it's undetectable (certainly by average m…

But this only works if all views of the images employ your client... If I download an image (screenshot if necessary), modify it, and host it myself, how does the system work then?

And, unless all users trust only things viewed securely, and distrust things viewed nonsecurely (out of your client), then misinformation and fake photos can still propagate, right? (Or, how does the system handle this?)

Re: Signs that can reveal a fake photo (2017)

#27

Post by kkielhofner »

kc0bfv wrote: post #16
hdm41bc wrote: post #14

Is this a solvable problem by requiring camera manufacturers cryptographically sign photos and videos created on those devices? If that’s in place then it seems like it could be the basis for chain of custody of journalistic images backed by a blockchain. This seems like the only viable solution to me since any AI powered solution would just be a cat and mouse game.

In this scenario, it would almost certainly have to be that manufacturers would have to build cameras that cryptographically sign the images and videos. The cameras would have to be able to have that ability, install of the manufacturers doing the signing. And then what would the Blockchain provide in this case? A chain of cryptographically signed certificates back to a manufacturer is basically the same system we us…

The problem with using certificates is any media signed by a party (by nature) traces directly back to that source/certificate. With a certificate-based approach I can imagine something like Shodan meets Google Image Search being used to make it easier to source media for the purposes of enhancing training for an ML model. Needless to say I have serious concerns about this approach.

This is why our approach only embeds a random unique identifier in the asset and requires a client to extract the media identifier to verify integrity, provenance, etc.

There are also two problems at play here - are we trying to verify this media as being as close to the source photons as possible, or are we trying to verify this is what the creator intended to be attributable to them and released for consumption? The reality is everyone from Kim Kardashian to the Associated Press performs some kind of post-sensor procession (anything from cropping, white balance, etc to HEAVY facetunning, who knows what).

Re: Signs that can reveal a fake photo (2017)

#28

Post by z5h »

I tried to prove that crops which do not preserve photographic centre are detectable https://physics.stackexchange.com/a/367981/3194

This was after photographers seemed to not believe this was the case https://photo.stackexchange.com/q/86550/45128

In any case, detecting cropped photos could be a way to detect that something has been intentionally omitted after the fact.

Re: Signs that can reveal a fake photo (2017)

#29

Post by [deleted] »

z5h wrote: post #28

I tried to prove that crops which do not preserve photographic centre are detectable https://physics.stackexchange.com/a/367981/3194 This was after photographers seemed to not believe this was the case https://photo.stackexchange.com/q/86550/45128 In any case, detecting cropped photos could be a way to detect that something has been intentionally omitted after the fact.

[deleted]

Re: Signs that can reveal a fake photo (2017)

#30

Post by jobigoud »

z5h wrote: post #28

I tried to prove that crops which do not preserve photographic centre are detectable https://physics.stackexchange.com/a/367981/3194 This was after photographers seemed to not believe this was the case https://photo.stackexchange.com/q/86550/45128 In any case, detecting cropped photos could be a way to detect that something has been intentionally omitted after the fact.

But cameras aren't perfect pinholes though. The center of the sensor and the optical axis of the lens are already not perfectly aligned, and the sensor is not necessarily perpendicular to the lens barrel. These distortions might be larger than any change of size due to an object being in the periphery of the field of view, especially for longer focal length where the rays are more parallel.
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