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  Previous versions of taob's message #10544815 « D800: 12-bit RAW vs. 14-bit RAW »

  

taob
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Re: D800: 12-bit RAW vs. 14-bit RAW


afm901 wrote:
A 12-bit file has 4096 colors per channel or 12288 colors for a three channel RGB file
A 14-bit file has 16384 colors per channel or 49152 colors for a three channel RGB file


I'm hoping you now realize that you multiply the numbers together. You don't add them up. A three-channel (RGB) 12-bit file can theoretically represent 2^12 x 2^12 x 2^12 different colour values. That's not 4096 + 4096 + 4096, but rather 4096 x 4096 x 4096 = 68719476736, or almost 69 billion colours. A 14-bit file results in 4398046511104, or almost 4.4 quadrillion colours.

It is believed that the human vision system can distinguish about 10 million colours. A 12-bit file is able to represent over 6000 times as many colours as we can see. A 14-bit file, over 400,000 times as many! To put it another way, I could show you about 440,000 different colours from a 14-bit file, and you would swear they are exactly the same colour.

All those extra colours are needed for two reasons. If we only had exactly 10 million colours to work with, they might not be the same 10 million colours our eyes can see. Everybody sees colour differently. So we need something that can encompass all of human vision (or at least as much of it as possible). The second reason is what we are talking about in this thread: the ability to push and pull an image so that the result still has enough colour information to recreate those 10 million colours we can see.



Apr 15, 2012 at 02:56 PM



  Previous versions of taob's message #10544815 « D800: 12-bit RAW vs. 14-bit RAW »