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Extended bits per pixel mode for supported cameras

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Offline mlietchnyipout

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Extended bits per pixel mode for supported cameras
« on: 01 / July / 2009, 17:55:52 »
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As I'm diving in code for another stuff, I see in camera properties what some cameras use 10 bits per pixel but 12 is supported except for curves (cf. "CAM_SENSOR_BITS_PER_PIXEL" property).

So, is this really supported (ie. disable curves and set bpp property to 12) in "native" by builds or is there are some changes to do in code?


Hum, why that?.. Because if you are looking for high quality, shooting in 12bpp is a huge advantage (4096 vs 1024 levels of value recorded) in dynamic and you may using RAW/DMG output, so you can use curve features in software (more accurate, using records pref', etc.).
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Offline fudgey

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Re: Extended bits per pixel mode for supported cameras
« Reply #1 on: 01 / July / 2009, 18:50:30 »
12 bits code is there for some of the newer cameras that use 12 bit RAW images. If CHDK builds with 10 bits for your camera, you cannot get more. It's debatable whether those two extra bits are of any use due to high level of noise, though.
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Offline mlietchnyipout

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Re: Extended bits per pixel mode for supported cameras
« Reply #2 on: 01 / July / 2009, 21:11:10 »
Ok, thanks for the information.

Quote from: fudgey on 01 / July / 2009, 18:50:30
(...)
It's debatable whether those two extra bits are of any use due to high level of noise, though.
What do you mean?
Are you speaking about the fact what the 12bpp is set by a logical multiplication from the 10bpp like in _40D for exemple_ 14bpp DSLR camera?
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Offline reyalp

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Re: Extended bits per pixel mode for supported cameras
« Reply #3 on: 01 / July / 2009, 21:59:33 »
Quote from: mlietchnyipout on 01 / July / 2009, 21:11:10
What do you mean?
Just because the framebuffer contains 12 bit values does not mean there is 12 bits of actual data.

See http://chdk.setepontos.com/index.php/topic,2468.msg30570.html#msg30570
That's before you factor in noise and the higher blacklevel.
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Offline mlietchnyipout

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Re: Extended bits per pixel mode for supported cameras
« Reply #4 on: 01 / July / 2009, 22:45:47 »
I think you are fully right.
Like I said, we can find the same thing in new DSLRs (with 14bpp). There's a 'adjustment' of the dynamic by a logical process to match to a large bpp. Some 'unexpected returns' are an offset level very high (can be a problem in low light condition when using 'basic' RAW), or a noise level most important (of course, because all values are multiplied, noise level is too).
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