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Comment by timbre | Hacker News Reader

The method at least is very different. The Google app is doing structure from motion, which essentially uses parallax to get the 3D shape of the scene. From there, you can blur/deblur according to depth. The Nokia app uses focal sweep, i.e. it just takes lots of pictures of the same scene focussed at different depths. I'm not sure what the pros and cons of each approach are.

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I only used Google version but I would guess that:

Nokia: - Nokia approach requires better lens with low aperture, because shallow DOF is done physically not using algorithm - Refocus on Nokia seems to be super fast, because they just change the picture which is used

Google - can use any lens, as bokeh is just calculated - you can change parameters of bokeh (very shallow DOF or not so much) - it requires a lot of computational power, so it take a lot of time to modify the photo

The Nokia app requires a longer exposure time, encompassing multiple shots, which basically means that anything moving is a no-go. The quality of its pictures is theoretically superior, though, because the depth effect comes from the photos themselves, and not a simulation.

Google's version, on the other hand, works with only a single photo, so it's more versatile. It may suffer issues with quality, though (arising from the difficulties in accurately extracting depth values from a 2D image). That has yet to be seen.

> Google's version, on the other hand, works with only a single photo, so it's more versatile.

This doesn't seem to be what everyone else is saying. Most people here are saying it takes multiple shots as you move the camera.

That is not true, Google version requires you to take a photo for several seconds while slowly moving phone upwards. Both methods take probably same amount of time.

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