AI resistant blurring

[nxxxse]

This is no news for security people. Blurring faces still carries information. There were research articles years ago. I just did a quick search and found this: https://today.duke.edu/2020/06/artificial-intelligence-makes-blurry-faces-look-more-60-times-sharper. And of course quite recent is this one: https://www.vice.com/en/article/xgdq87/deepfakes-japan-arrest-japanese-porn

I have not checked what the state of the art blurring is but when I did some research 2016 there were basically two options:

• Black rectangle over face.
• Place another face over the one you are about to blur, then blur it.

I just had an idea for another option. Random pixel colors for blurring.

Would be great if you could look into this. I found your app on F-Droid. The only other relevant app seems to be https://guardianproject.info/apps/obscuracam/. They support black rectangle, I guess for that reason.

[LeonidArefev]

Why you don't want to use Pixelate filter with maximal power in this case? Our App support it. You will see few big squares. I suppose this is what you want...

[nxxxse]

I was wondering. I guess there are still too many pixels even with the maximum setting so this leaks too much information about the original face.

[nicolas-raoul]

@nxxxse

As the article you mentioned says, AI can imagine portraits by adding features that weren’t there in the first place, but it can not guess what were the actual original features.

It won’t turn an [...] unrecognizable photo [...] into an [...] image of a real person. Rather, it is capable of generating new faces that don’t exist, but look plausibly real.

So, I don't think any AI can significantly reverse PrivacyBlur's face blurring, at least for now.

On the other hand, car number plates are much easier for AI to guess even if blurred heavily, because there is a limited number of letters/digits and fonts.

[dngray]

The bottom line is that when you need to redact text, use black bars covering the whole text. Never use anything else. No pixelization, no blurring, no fuzzing, no swirling.

https://bishopfox.com/blog/unredacter-tool-never-pixelation

I think it might be worth having a filter which is just a black square, this is really the best way when redacting documents/text (you shouldn't blur that). The concern is someone might use this tool to redact a screenshot.

I think it's worth somehow warning users not to use blur for documents or text. If you look at anything that is ever released by government agencies through freedom of information, or unclassified releases they always use black bars too.

We're wanting to recommend this tool on privacyguides.org under our Android page, so we have put a warning there: https://github.com/privacyguides/privacyguides.org/pull/690/files#diff-18bdf09879fb1fc8dfe54ac7388ba550921ae33222dc6f14a6a8f5c285e8bf59R8

I had been tempted to suggest users should use Imagepipe for redacting text, unfortunately that only seems to be available on F-Droid.

[lavendercolor]

Perhaps adding a random function to pixelation could work?

[jermanuts]

This was discussed here https://discuss.privacyguides.net/t/remove-privacyblur/11560