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Re: [OM] What would you buy?

Subject: Re: [OM] What would you buy?
From: Moose <olymoose@xxxxxxxxx>
Date: Mon, 13 Jan 2014 16:52:49 -0800
On 1/13/2014 4:11 PM, Chuck Norcutt wrote:
> How does anyone know this?  The numbers 23 and 24 each occur only once
> in the text of the DPReview coverage of the NEX 7.  Neither instance has
> any connection with bit depth.  I think something is being misquoted
> here.  You can't have 23 or 24 bits of color depth if the sensor only
> has 14.

It seems they explain what they mean, as well as several other measures, here. 
<http://www.dxomark.com/About/In-depth-measurements/Measurements/Color-sensitivity>

What I think they are saying is that, due to various limitations of sensor, 
filters, electronics, etc., that the number 
of colors produced which may be distinguished from each other is far fewer than 
implied by 14 bit per channel output.

They determine the number of separate colors, and calculate the number of bits 
required to represent that number in 
binary. Although it sounds sort of like bits per color channel, it can't be 
deconstructed into that as they are each 
different in their contribution to a fairly complex combination.

It's an awkward sort of measure, as it will tend, as it did with you and me, to 
lead to thoughts of bit depths - but it 
isn't that. I'm not sure why they don't just use the number of colors.

There's a certain imprecision it the terminology, as well, from the very 
digitization that is used to create the 
measure. For example, 23 bits is 8.4 millions of colors (MCs), and 24 bits is 
twice as many. So an easy assumption could 
be that the A7 resolves twice as many colors as the E-M1. But the difference 
could be only one color, if the E-M1 just 
happened to be able to distinguish 8,388,608 and the A7 one more than that.

It may be that they have chosen this notation just because the true, but but 
somewhat imprecise, numbers would imply a 
much greater difference than would be observable? 23 vs 24, as dimensionless 
numbers, imply a small difference, on their 
face, as opposed to, to pick a couple of numbers, 8 MCs vs. 12 MCs, which seems 
like a big difference.

Head Spinning Moose

-- 
What if the Hokey Pokey *IS* what it's all about?
-- 
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