Chris, You're correct about some raw imaging processing mostly internal in the C920, under some circumstances.
Now, as far as CPU and Memory usage, we're probably talking a lot of Apples and Oranges, (or Apples and PCs) here. And it's obvious that 5MP take more resources than 2MP regardless of any on-camera processing...once the image is in the machine, then what?
Machine is HP Pavilion p6531p
64bit Win 7 Pro - 8GB RAM
ATI Radeon 4200 Video 256MB
AMD Athlon II X4 635 at 2.9GHz
Cameras raw 1080i on
Logitech Software: everything in idle with single live camera
C920: Total CPU all processes: 10% +/- Cam about 5% Total Sys Memory usage 33%
C910: Total CPU all processes: 15% +/- Cam about 10% Total Sys Memory usage 34%
Max CPU (all processes) on camera load, either cam, was approx. 25-35% with the Logitech software.
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Using 2 different capture programs, (Cybermedia YouCam & Avid Studio) No Logitech Software.
Import set for 1024x576 for each cam,
There was no difference in resource usage compared
to the Logitech Raw. (Yes, the two other applications wanted varying resources,
but the 'camera cost' remained at approx. 5 & 10 CPU average as above.)
Max CPU (all processes) on camera load, either cam, was about the same, approx. 25-35%.
Again, the C910 wanted about 1% more system memory than the C920.
So it's all about the system (design & limits) we're attaching them to, and what our personal wishes and goals are, it seems... .
Oh, a 1024x576 image would still be similar sizes, depending on content, regardless of it's source, (depending on compression algorithm and percentage)
Mike