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pvamic41

Moorhead, US
24 posts

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pvamic41 Gold Member Nikonian since 03rd Jan 2007
Sun 18-Jan-09 12:19 AM

D700, CS4, LR2, Vista

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.

Paul Amicucci
http://www.pbase.com/paulamicucci

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dankeny

Roland, US
1555 posts

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#1. "RE: 14b vs 16b" | In response to Reply # 0

dankeny Gold Member Nikonian since 29th May 2006
Sat 17-Jan-09 11:49 PM

16 bits is capable of representing 14 but not visa versa. CS4 has limited 32 bit support. Lots of head room.

With 3 bits I can count to 8 (unless I know about 0, then 7). With 2 bits, I can count to 4. I can represent any number from either system in 6 bits.

What was your question?

David

gpoole

Farmington Hills, US
4122 posts

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#2. "RE: 14b vs 16b" | In response to Reply # 0

gpoole Platinum Member Fellow Ribbon awarded for his excellent and frequent contributions and sharing his in-depth knowledge and experience with the community in the Nikonians spirit. Awarded for his very generous support to the Fundrasing Campaing 2014 Writer Ribbon awarded for his article contributions for the Articles library and the eZine Nikonian since 14th Feb 2004
Sat 17-Jan-09 11:57 PM

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.

Gary in SE Michigan, USA.
Nikonians membership - My most important photographic investment, after the camera.
D4, D810, D300 (720nm IR conversion), D90, F6, FM3a (black), FM2n (chrome)
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PaulBennett

US
321 posts

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#3. "RE: 14b vs 16b" | In response to Reply # 0

PaulBennett Registered since 09th May 2008
Wed 21-Jan-09 05:31 AM

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.

G