Dynamic range and RAW file "bit depth"

Started Jan 25, 2014 | Questions thread
Iliah Borg Forum Pro • Posts: 25,499
Re: Dynamic range and RAW file "bit depth"

GordonBGood wrote:

szhorvat wrote:

I found this about linearity. The plots show what you said: it's linear in the shadows and the highlights are compressed. I wonder if this compression is engineered in some way (it would make sense to do it).

The data from your link is does indeed show that the output of sensors is non-linear as it approaches saturation electron density of the sensor substrate, but that is a region that is normally never used in most current digital cameras, which only generally use the sensors in there generally linear range. A very fiew cameras (such as the Pentax K-5 series) do push the sensor up into this non-linear range for their extended "lower than base ISO sensitivity" range, which works fine especially if raw development then compensates for the non-linear response.

From my attempts to systemize it, typical histogram for a camera where the full well is used shows a hump in the blown-out area, like this:

I do not see this type of highlights level distribution on Pentax 5-series at ISO 80 setting. Was it some PTC study you did on "5" that shows the full well is used at ISO 80?

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