PIX 2015

Dynamic range and RAW file "bit depth"

Started Jan 25, 2014 | Questions thread
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DSPographer
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Re: having pondered this, why not have 17 bit raw file option?
In reply to Jack Hogan, Jan 27, 2014

Jack Hogan wrote:

DSPographer wrote:

This isn't just wasteful of file bits, it also could significantly slow down the raw converter. In column parallel ramp converters like Sony's Exmor sensors use, having a nonlinear ramp dramatically speeds up the conversion process. So, on many cameras that have "14-bit" raw capability the conversion step size is not really uniform, instead it increases approximately as the square root of the level, so that the time to perform the ramp conversion is not excessive.

Hi DSPographer,

Interesting. How does having a non-linear ramp affect accuracy of the linear ADC output throughout the range?

Here is a paper which discusses non-linear ramp converters of the sort Sony uses in their Exmor sensors:

http://www.imagesensors.org/Past%20Workshops/2005%20Workshop/2005%20Papers/44%20Otaka%20et%20al.pdf

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