Effect of RAW bit decimation: Panasonic GH5s case

[Guillermo Luijk]

I knew recently that the Panasonic GH5s is the only M4/3 camera with genuine 14-bit RAW files. But do those extra 2 bits really make a difference? 14-bit cameras have existed in the past where RAW files could be encoded with 12 bits without practical loss. The same applies to all 16-bit MF cameras and backs, where 14-bit RAW files would have sufficed.

Taking this high contrast scene shot at IO160 (base ISO):
http://guillermoluijk.com/misc/decimation2.jpg

I picked the deep shadows area, where extra bits could be of help, and built a synthetic DNG RAW file with increasingly bit decimation over the same area: 14, 13, 12,..., 6 bits:

http://guillermoluijk.com/misc/decimationfull.jpg

The result with 14 bits is hardly different to 12 bits (I can see some extra magenta cast in the 12-bit version). From 10-bit (incl.) the posterization is clearly visible.

Synthetic RAW file to play with it here.
Original RAW file here.

Regards

[fdisilvestro]

Thanks for the analysis, I wonder how a 14 bit file would compare to a file created from the 12 bit + 2 bit random

[SrMi]

Here is a relevant article:

https://www.strollswithmydog.com/how-many-bits-to-fully-encode-my-image/