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Comment by DennisAleynikov | Hacker News Reader

The way rolling shutter and computation photography works that kind of glitch is exactly the kind that is possible

Not common by any means but plausible

Edit: tried it with my iPhone and it’s definitely tricky to do, if I get a photo that demonstrates this effect I’ll post it publicly. The window of opportunity to take such a photo is extremely tiny

And it would definitely be much easier to photoshop it than to capture it “in camera”

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Rolling shutter won’t cause this: the readout of the whole frame happens in a fraction of a second, and I don’t see someone moving their arms quickly enough to trigger this kind of glitch. You usually see rolling shutter effects with objects that are moving very fast, like wheels and propellers.

Yeah for sure, it would take a freak accident to move your arms so quickly and suddenly and have them end up sharp in the end result.

The closest I’ve been able to achieve in a few minutes with my phone is a blurry vs non blurry image of my hand in the reflection vs in real life. Pretty hard to pull off this kind of double exposure trick when the software isn’t actually intending to take double exposures

I wonder if this is easier to pull off with "night mode"? A few tests suggests that the iPhone is indeed quite choosy with the exposures that it stacks, so there's definitely a possibility of it picking-and-choosing parts of pictures to stack.

And perfectly stable hand what held that phone, not making a blur anywhere.

Optical image stabilization can explain that part

Is it possible that the phone was very busy/lagging and what would normally take a fraction of a second took a couple of seconds?

The camera hardware implements the readout upon command from the application processor (what you'd normally call the "CPU" of a phone), and the readout does have to be carefully timed in order to ensure a consistent exposure across the frame. So, whether the phone is overloaded or not will not affect readout speed (and therefore the rolling shutter effect).

This does not preclude the possibility that some other photographic process was stalled, such as HDR stacking.

Rolling shutter doesn't produce such clean discrete artifacts, but more of how rotors are bent for helicopters when readout between motion isn't fast enough. This image is as if global shutter took 3 separate shots of 3 separate poses within a space of 0.12~0.15s each

Yeah my bad this isn’t rolling shutter, this is multi frame compositing and likely filtering out blurry frames randomly because the arms did move

Perhaps this was some kind of rare memory fault where it took a series of photos and there was some kind of corruption that caused elements of each to be merged.

Or perhaps there was some weird fault that meant different sections of the photo were taken at discreetly different times and then stitched together.

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