A question on how dynamic range is interpreted in an 8-bit REC.709 codec for video

[Bunkey]

Hi there Photrio forum,

I've read up on the subject of dynamic range and the limitations of the REC.709 format but have not come across anything which addresses this question directly -

Say I'm filming a scene which presents an arbitrary 18-stops of dynamic range to the camera;

I'm using a typical DSLR with a sensor capable of registering 13-stops of dynamic range;

I use that camera to record video in a REC.709 format H.264 codec, which is limited to displaying 8-bits/stops of dynamic range.

Does the image recorded by the camera a) compress the full 13 stops of information registered by the sensor into the effective 8-stop range of the 8-bit codec, or b) does it just discard any information seen by the sensor which falls outside an 8-stop range of the codec even if the sensor is capable of registering it losslessly?

I'm leaning toward the answer B and that this is why we shoot with a flat curve picture profile to better achieve scenario A; it would be nice if somebody could confirm what's going on?

Thanks, Ben.

 

[Alan Edward Klein]

I'll go with a).