Author Topic: The difference between DGO on C70/C300MKIII vs ML HDR besides interlacingscan?  (Read 1152 times)

NightlyMattya22

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Canon recently published a white paper for their DGO sensor on C70/C300MKIII

After viewing this image, i wonder, whats the difference between Canon`s and ML`s Dual ISO? They seem to both be drawing info from dual gain,
instead of two different set of amp?



Audionut

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The img link is broken. The direct link in your other (deleted post) lead to a broken page.

Perhaps you could just link the whitepaper.

darthivm

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I would be also interested in this discussion:). Please post some links for the canons implementation, so others could participate too:)

NightlyMattya22

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Audionut

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ML dual_iso is as a result of reverse engineering. It was noticed that there were more then one amplifier (attached to the sensor) that could be adjusted separately. This allowed dual_iso, but does have some drawbacks.

Canon's solution is bespoke. It is likely that there are still more then one amplifier (column gains iirc?), however, instead of finding more DR by adjusting these amplifiers separately, with all of the drawbacks associated with, Canon doesn't flush the photosites when they are first read, and instead retains the photosite "memory" for more than one amplification pass.

ML....
Code: [Select]
2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
next 2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
next 2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
etc...
etc...

Then a post application is used to match ISO yy brightness to ISO xx brightness.


Canon scans the entire image at ISO xx, then scans it again at ISO yy (and presumably could continue to scan it however often they want, to a point). Basically this is ML dual_iso with none of the drawbacks.
Oh and I assume all of the post processing is done in camera. Would be nice if they allow a raw of each scan to be saved.


NightlyMattya22

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ML dual_iso is as a result of reverse engineering. It was noticed that there were more then one amplifier (attached to the sensor) that could be adjusted separately. This allowed dual_iso, but does have some drawbacks.

Canon's solution is bespoke. It is likely that there are still more then one amplifier (column gains iirc?), however, instead of finding more DR by adjusting these amplifiers separately, with all of the drawbacks associated with, Canon doesn't flush the photosites when they are first read, and instead retains the photosite "memory" for more than one amplification pass.

ML....
Code: [Select]
2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
next 2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
next 2 lines of image signal at ISO xx
next 2 lines of image signal at ISO yy
etc...
etc...

Then a post application is used to match ISO yy brightness to ISO xx brightness.


Canon scans the entire image at ISO xx, then scans it again at ISO yy (and presumably could continue to scan it however often they want, to a point). Basically this is ML dual_iso with none of the drawbacks.
Oh and I assume all of the post processing is done in camera. Would be nice if they allow a raw of each scan to be saved.

  But wouldnt there be a lag?
  IIRC, ZCAM has done something similar to there SONY sensor. As a result, the HDR mode on that camera has some serious aliasing and rolling shutter effect.
  I know ARRI has a DGO sensor, that, if I am right, simultaniously outputs two different set of amplified signals to proccess. I assume that is what Canon is doing?


Audionut

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  But wouldnt there be a lag?

IIRC, the whitepaper says it can do 60fps.

if I am right, simultaniously outputs two different set of amplified signals to proccess. I assume that is what Canon is doing?

Depends on exactly what you mean. For this discussion, exposure means one actuation of the shutter.

Samsung smart phones does HDR with 2 different exposures. This must be the case because of the motion artifacts.

Canon is doing HDR with one exposure. Shutter opens, sensor captures the signal. This signal (the exposure) is then stored in a memory.
From there, it is amplified twice. Once at minimum amplification to captures the highlights, and once with a higher amplification to capture the shadows.
These two differently amplified images (of exactly the same exposure) are then blended together to deliver the final HDR image.

NightlyMattya22

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IIRC, the whitepaper says it can do 60fps.

Depends on exactly what you mean. For this discussion, exposure means one actuation of the shutter.

Samsung smart phones does HDR with 2 different exposures. This must be the case because of the motion artifacts.

Canon is doing HDR with one exposure. Shutter opens, sensor captures the signal. This signal (the exposure) is then stored in a memory.
From there, it is amplified twice. Once at minimum amplification to captures the highlights, and once with a higher amplification to capture the shadows.
These two differently amplified images (of exactly the same exposure) are then blended together to deliver the final HDR image.

I see, :)
thanks