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• #84206 topikk senior tag topikk #84205

  Új Válasz 2017-10-17 13:29:46 #84206

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  http://www.imaging-resource.com/news/2017/03/14/panasonic-cpplus-2017-gh5-dev-story-on-chip-pdaf-affordable-4k

  DE: Moving on to a question about autofocus: The specs for the GH5 say that it's faster than the GH4 for Depth from Defocus. So far, Panasonic has focused most of your attention on DFD, if you'll pardon the pun. You haven't yet done anything with phase-detect pixels on the sensor. Is there a technical limitation for on-chip phase detect that makes it less desirable or is just a matter of intellectual property and licensing things? Or do you feel that with DFD that you really don't need to have phase detect?

  Panasonic: Phase detect on the image sensor will cause image defects [which] are very easily detected when the [subject] is moving slowly. For example, if the object is moving very slowly and [phase detect is used], so this interaction makes…

  DE: As an edge crosses a phase detect pixel…

  Panasonic: …it is not smooth, yeah. So to avoid those kinds of artifacts, we do not use the phase detection.

  DE: Very interesting, because even if they're recording the light for image formation, the phase detect pixels are only seeing half the light because they're shaped differently, and so you have to do some processing to make up the difference.

  Panasonic: Yeah, that's another reason, yes.

  DE: And they're doing interpolation, like a nearest neighbor or median filter or something like that…

  Panasonic: Right, right.

  DE: …and so if you have a sharp edge coming across [the phase-detect pixel] slowly, it will flicker a little.

  Panasonic: Right.

  DE: Ah, that's very, very interesting.
  Panasonic's Depth from Defocus technology does away with the hunting required for contrast detection, yet avoids the compromises of on-chip phase-detection too.

  Panasonic: So that's why we focused on the improvement of the contrast detection autofocus control. We have an R&D section who made research on that application of the DFD technology to autofocusing, and [the] GH4 was the first generation of the DFD technology. In the GH5 it's the second generation of the DFD technology, implementing faster DFD frame processing speeds and the number of [distance samples in the depth map].

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