Dynamic range and RAW file "bit depth"

Started Jan 25, 2014 | Questions thread
xpatUSA Forum Pro • Posts: 14,261
Re: Non linear for sure.

Y Hafting wrote:

There is stricly no need for having the raw file storing the exact sensor readout either. Processing comes cheap compared to storing data, so in theory there is no guarantee that the raw file contains actual raw sensor data. The fact that the image size varies with the visible noise in canons cr2 format indicates that it is compressed.


Quite so!

In the early Foveon-based cameras, a considerable amount of in-camera processing is done, including dark-frame subtraction and especially linearization. For my SD9 camera, Foveon claims 77,000e- for 'well full' but they also mention 45,000e- as being the top of the linear range. They quote 70e- for noise but a possible 40e- with dark frame subtraction.

In terms of 'stops' (on a good day) we might therefore get log2(45,000/40) = 10 stops for reasonably linearity, and about 3/4 stop headroom above that. Foveons need all the headroom they can get

I hate 'stops' in this kind of discussion , a bit of a dB man myself . . . .

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