It's amazing how well my eyes reconstruct the original image from the demo http://persistent.info/web-experiments/temporal-dithering/ I had to blink (to capture a "screenshot" in my eyes) to see that the distorted frames were really there.
Now, obviously, the way my eyes do it is temporal averaging. Thus, a camera with a sufficiently long exposure would capture it just the same. What it does prevent is screenshots, taken internally by the device - which generally don't do averaging or have a concept of "exposure". Of course, that could be implemented, but it's not standard at present.
He mentions using more than two frames - a less precise approach is to just add massive random noise over an indefinite number of frames (a noisy video of a static image), and instead of taking care that they cancel out, just rely on statistical convergence. Depending on how much noise is added, it gets more difficult to see the original.
I guess there's a risk that only a little noise is added in some frames, revealing the person. So perhaps instead of adding random noise, you use offsets of a legitimate face. This would make either single frame actively misleading, and perhaps not obviously distorted. Your eyes wouldn't be deceived (I think...), because they average the pixels, like a long exposure.
Also, one could selectively apply the technique - as google street-view blurs out people's faces, but nothing else. This might reduce the flicker.
> It's amazing how well my eyes reconstruct the original image from the demo
Hmm. It didn't work for me at all. On the latest Firefox beta it was flickering at about 10fps (ballpark guess), which was slow enough for me to see the individual images and made it look like the normal picture plus horrible static (IE, analog TV noise of old). It also took 40% of my CPU.
It looks better on chrome (and only took 10% CPU), but there's still a lot of noise there. And the flickering is unbearable.
Now, obviously, the way my eyes do it is temporal averaging. Thus, a camera with a sufficiently long exposure would capture it just the same. What it does prevent is screenshots, taken internally by the device - which generally don't do averaging or have a concept of "exposure". Of course, that could be implemented, but it's not standard at present.
He mentions using more than two frames - a less precise approach is to just add massive random noise over an indefinite number of frames (a noisy video of a static image), and instead of taking care that they cancel out, just rely on statistical convergence. Depending on how much noise is added, it gets more difficult to see the original.
I guess there's a risk that only a little noise is added in some frames, revealing the person. So perhaps instead of adding random noise, you use offsets of a legitimate face. This would make either single frame actively misleading, and perhaps not obviously distorted. Your eyes wouldn't be deceived (I think...), because they average the pixels, like a long exposure.
Also, one could selectively apply the technique - as google street-view blurs out people's faces, but nothing else. This might reduce the flicker.