It seems it is no longer secure to blur face.
It is possible to use image processing techniques to unblur or reconstruct a face, and facial recognition technology may still be able to identify a person even if their face is blurred (this is also highly depends on the blur algorithm).
Instead, blacking/whiting something is a much better option for anonymity. This can easily be done via each device’s built-in annotation feature or through the app that use to share the image like Signal which remove the need for a separate application like Privacy Blur and Pocket Paint.
it hasn’t been updated in a few years, but ObscuraCam comes to mind. similar face detection software from the guardian project, with multiple options for it including redacting (with solid color, and other options)
The only “maintained” service that comes to my mind is… Signal, since you can take a photo and blur the face or draw in the face to hide it with something like Note to Self
Another method is using the device’s built-in blur tool, but that’s very device-specific. AFAIK, Samsung and Pixels have that capability.
As far as I know this app still works though, I don’t think we should be too quick to remove seemingly unmaintained apps simply because they haven’t been updated in a while. If an OS update breaks PrivacyBlur it may still receive a patch in the future for example, we don’t really know until that happens.
Some of these tools like PrivacyBlur are single-purpose tools which can be “complete” after all. This app only does one thing, it’s not a browser or operating system.
Also, we do already have a warning about blurring text.
True enough I guess. The only issue can be if apps depend on old API levels it creates a lot of work for developers to catch up when those are deprecated and then eventual removal from Play etc.
You can add the warning to the knowledgebase section.
You should never use blur to redact text in images. If you want to redact text in an image, draw a box over the text. For this, we suggest apps like Pocket Paint.
Reading through the linked paper and other resources, I don’t think concrete security issues with face blurring have actually been identified, especially with the pixelate filter (as opposed to gaussian blur) present in this app.
If we want, I’d be fine with amending the existing warning to say:
Blurring is not as secure as simply drawing an opaque box (i.e. a black box) over a portion of an image. You should especially never use blur to redact text in images. For this, we suggest apps like Pocket Paint.
…but not really to say anything about faces specifically.
I think it’s generally good to just recommend people to black out things. This is much more secure.
With documents however you should be wary when blocking out words with black bars. I have recently seen a talk (OSINT - How AI fuels disinformation - media.ccc.de) that shows how those words could be predicted pretty accurately. Although if it’s just for personal data that’s completely fine and effective.
I don’t know if this is a problem, but the app you linked is much more than just an app to blur faces. You can edit EXIF, erase background, apply filters, crop images, create a PDF file, comparing images, etc… The list goes on…
Nope. They already suggest Pocket Paint which does a lot of things too… ImageToolbox maybe be a better alternative for both PrivacyBlur and Pocket Paint.
Well the solution to that is a large slab of black text over the whole line, not individual broken up boxes that are exactly the same size as the characters being redacted.