12-bit or 14-bit RAW

Started 1 month ago | Discussions thread
ForumParentFirstPrevious
Flat view
981S Regular Member • Posts: 132
12-bit or 14-bit RAW

I have been reading about the differences between 12 vs 14 bit RAW (especially given the 100MB uncompressed 14-bit files I am getting out of the D850), and would like to understand the differences at the file level.

I am reading how the RAW file stores the tone values linearly while we observe light exponentially. As a consequence 50% of the available data in the 12-bit or 14-bit encoding is used to store the tones in the highest 1-EV range that the camera can record. The difference between 12-bit and 14-bit would then be that a 14-bit RAW would have 4 times as much space to store the tones in each 1-EV range of tones.

But is this what is actually happening though? It just seems like such a waste of space to use 50% of the available storage capacity for a 1 EV range where we can’t distinguish at all that many tones. Almost all the information I can find describes it this way, except for Ken Rockwell who writes this:

“When you select 12-bit, you're still getting 14-bit performance in the dark where you need it. All that changes is that the 12-bit position merely uses a look-up-table to skip between values at the bright end, where we far more precision than needed anyway.”

This makes sense to me and would indicate that the RAW files only store the sensor voltages linearly up to let’s say the 50% voltage value, using e.g. 95% of the 12 or 14 bit range, and then for the last stop it could map this to the top 5% of the 12 or 14-bit range. I can imagine that how this is done could be brand-specific.

Ken’s point is that if the voltage output is stored in this way, then the 12-bit encoding could very well have more than enough accuracy, making any difference not visible to the human eye.

However I could not find this explained anywhere online, can someone confirm this or point me to a place where it is explained in more depth?

 981S's gear list:981S's gear list
Nikon D70s Nikon D300 Nikon D850 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S DX Nikkor 17-55mm f/2.8G ED-IF +7 more
ForumParentFirstPrevious
Flat view
Post (hide subjects) Posted by
MOD TOF guy
MOD TOF guy
ForumParentFirstPrevious
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow