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[OM] Re: If you think all bits are created equal for image storage, you

Subject: [OM] Re: If you think all bits are created equal for image storage, you need to read this, even though it is long. [was RAW Bit Depth]
From: Moose <olymoose@xxxxxxxxx>
Date: Sun, 08 Apr 2007 14:22:01 -0700
Winsor Crosby wrote:
> Variation in the mapping of values onto the RAW format had not  
> occurred to me. Thanks, Moose, for such a thorough discussion of it.
>   
You are more than welcome. It was useful for me to think through more 
throughly something I only understood vaguely. As Andrew W. said, I 
think this "is fundamentally important stuff for really understanding 
digital" images.

What's funny, and fun, is that all my mapping discussion is almost 
purely speculative reverse engineering:

- You can't put enough brightness range for the purpose into an 8 bit 
file as I am familiar with them.

- The folks at Leica are strange in certain interesting ways, but have 
always been rather clever. So it seems unlikely they are crippling their 
camera to minimize write time and storage space in an era of plummeting 
storage costs.

- I wonder how they might be putting the full dynamic range into an 
8-bit file without loss?

- I know vaguely that 8-bit digital image files lose tonal detail at the 
shadow end.

- Put on thinking cap, ignore pain of stirring up quiescent 
neurons...........

- Oh, that might work! Is it possible in DNG?

- The one non-speculative piece - Yes, research shows DNG has that 
capability.

I have no information whatsoever about what Leica is really doing. I'll 
bet I'm not far off, though.

Now I want to know how the 8-bit to 16-bit mode conversion in PS is done.

Moose

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