Just curious if anyone knows where the extra 2bits comes from in post processing. Camera captures in 14b but when I open in CS4 it is magically 16b, is this a hash count or something. For that matter if I capture in 12b it shows as a 16b in CS. Am I missing something here or am I comparing apples and oranges.
All computers these days work with numbers that are 8, 16, 32, or 64 bits. Because 12 or 14 is bigger than 8, 16 bits are used to represent the digitized value inside the computer. Putting the A/D measurements into 16 bits numbers makes it much easier to write a computer program to manipulate the data.
The additional bits are initially zero, but the multiplications and divisions used in Bayer calculations, white balance, exposure correction, noise reduction, sharpening etc. will change these additional bits to something else. You can argue that any bits beyond the original A/D conversion are meaningless, but they still are there in the computed value. These extra bits certainly don't hurt anything.
Also throwing 12 or 14 or in the future 16 bit A/D converted values into 16 bits allows the Post Processing to use the same program, regardless of the original precision.
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You can call it hash count but it's really zero padding for faster processing as they would be using 16 bit processing which in dual core carries no time penalty. I hadn't notice any change in CS3 as I'm so accustomed to PS7 changing everything to 8 bits.