Digital BW, The Print

Part of the problem here is in thinking linearly. In fact, the way the 256  
steps of an 8-bit image are distributed are logarithmic and a great deal  
hinges on the dynamic range of the image. 128 steps of the total 256 steps  
are all used for the brightest 1 f-stop of the image. The next f-stop has  
only 64 steps, the next stop has 32. At the 5th f-stop you are down to  
only 8 steps. Fortunately our eyes are less sensitive to tonal changes in  
the darker areas that in the brighter areas. Never-the-less, with a 16-bit  
file, the 5th f-stop range has 2048 possible steps and you can therefore  
manipulate the data with less chance of introducing errors than with only  
8 steps available. Also, even though you end up printing in an 8 bit  
environment, that does not automatically limit you to 256 steps. As Roy  
Harrington has pointed out in his many discussions on the QTR mailing  
list, you can still get a smoother tonal range in the final print through  
the use of dithering if you have more than 8 bits of data available.
Steve

On Tue, 10 Apr 2007 12:12:22 -0700, amadou diallo <amadiallo@...>  
wrote:

> Clayton,
> I ran the gist of the early part of this thread by some Adobe
> engineers and beta testers. Aside from the standard "no benefit"
> response (of which I was guilty as well), those who had actually tried
> it concurred with your results, that in some cases bumping from 8 to
> 16bits before large edits yielded a benefit. The explanations were
> more anecdotal, than an official Adobe position on the matter, but
> thanks for putting this information out there. If I get any definitive
> technical explanations from Adobe I'll pass them on.



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