i built a tool for quickly scrubbing metadata from images and selectively painting / blurring faces and identifiable features. it runs on a phone or computer directly in the browser, and doesn't send info anywhere:

@abundance Is it open source? It would be amazing if this could be packed into an open source app so people could use it offline.

@abundance may i suggest using a more foolproof blurring method, for example mosaic instead of gaussian blur? especially since you have a radius adjustment, i think it might be easy for someone to accidentally not blur enough to prevent identification or reversal

@yatchi it uses noise and pixelization first! should be pretty sturdy, but would love an audit if you know how to reverse blur

@abundance i don't, but it's just that i noticed that you can turn the blur radius up to where it doesn't do much. i wouldn't want people to mess with that setting and be under the impression that it's good enough when it isn't

@yatchi thanks, yeah i agree- i need to constrain the blur radius to the current brush & canvas size, (the bigger blur options work with bigger brushes/images) but the math isn't linear so its not an instant fix

@abundance Isn't gaussian blur pretty trivial to reverse nowadays with deconvolution and modern GPUs?

Painting over the image would be a safer default....

@pyredrid it uses noise and pixelization first- should be pretty sturdy, but would love an audit if you know how to reverse blur

@abundance I've got no direct experience with reverse blur, but since the blur doesn't appear to actually be gaussian judging by the code comments, i'll give it a shot

@abundance Ok, so after some reading up on deconvolutions, messing around with that blur algorithm a bit, and using some publicly available deconvolution tools, I found a couple things:

-The algorithm used is not gaussian blur and results in way less recoverable information at your current default settings (brush size and blur size)

-Blur Radius drastically changes how much information can be recovered with Wiener deconvolution, even when faces seem visibly blurred enough

@abundance Basically its fine if the end user doesn't touch the default settings, but that's a bad, insecure idea

Instead of having Blur Radius be a separate UI from Brush Size, it would be better to just have one slider that scales both variables

@abundance Should be important to note that I'm not an expert in this field and literally spent less than an hour screwing around with publicly available tools and wikipedia articles. So take all of that with a grain of salt

@abundance please let us paint over with a solid colour instead of blurring

@abundance If I want to share this tool on other social media platforms, is it okay to do so?

If you are okay with the re-sharing, my instinct would be to screenshot your post and keep your display name and handle visible as to keep credit, happy to comply to specific instructions if you'd rather it be done in a different way.

@skiant you're welcome to just share the link - no need to link me here

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