Want to buy a phone for camera..

Started Aug 8, 2013 | Questions thread
Menneisyys Senior Member • Posts: 1,449
Re: (Galaxy S4/iPhone 5) vs (Nokia 808, 1020)

bigley Ling wrote:

if the iPhone HDR is from a single image, how come with faster moving subjects captured with HDR on, the image has ghosting where the subject was moving? I think it does take a multi exposure shot, but the processing has to be quick, so it does not necessarily do a full hdr, plus iPhone HDR is just for visual improvement of dynamic range, and not to make the image look unrealistic and surreal.

Basically, the stock Camera app - unlike with third-party ones - has access to the hardware. This is why it can sample the sensor twice in a row, with minimal time difference, all during the same exposure (during while the shutter is open).

Sampling twice during while the shutter is open also means the sensor can't be exposed with different shutter speeds; this is why the additional dynamic range is around 1 EV only, unlike with traditional (and very slow - shutter speed + ISO changing + opening/closing the shutter again generally takes a second; this is why the built-in HDR mode doesn't use this approach) approach.

BTW, I've made some shots where the HDR version of an image had more unrealistic colors (because of the different clipping of the separate RGB channels) than the non-HDR version. Of course, this has to do with clipping and not with the "plastic" colors of traditional large-EV  HDR methods.

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