Digital BW, The Print

Howard,

I think most experts agree that one can see the advantages/effects of
working in 16bit on the screen in the pixels of the image and in its
histograms, but where they still seem to disagree is whether these numerical
advantages of working in 16bit can be seen in the final print. If not, why
do it?

On the Colortheory list this topic comes up quite often, and did so again
recently. I have copied parts of Dan Margulis's recent comments and
challenge below:-


    "What I and other people have said is that we have tried to produce 
imagesdemonstrating that applying adjustments to a real-world color 
photograph in 6-bit could produce a better result under any conceivable set 
of
real-world circumstances, however far-fetched, than doing the same thing in 
8-bit. So far, however, we haven't been able to do it in even a single 
image, despite having used exactly the sorts of images and the sorts of 
maneuvering that we have been assured produces a night-and-day, totally 
obvious, you-are-a-recreational-user-if-you-don't-do-this difference.

Because I have given up on ever finding an image myself, I am reduced to 
hoping that someone like yourself can find that elusive single image which 
will demonstrate that 16-bit is better under at least some real-world 
circumstances.

.............................

However, if you (or any other list member) ever does happen to run
across such an image, you are most cordially invited to notify me offline so
that we can make arrangements to verify it and put it out there for people 
to see. This would be a significant service to everyone. If there is in fact 
a point where the use of 16-bit might become desirable, I'd certainly like 
to tell my classes about it.

As always, my only requests would be that it be a color photograph,
however bad or unusual, that might conceivably be used by itself in 
professional context; that the steps or series of steps taken to "correct" 
it,
however incompetent, are at least conceivable; and that the provider be 
willing to release it for publication to demonstrate the limited point of 
whether 16-bit correction can ever serve any useful purpose at all.

Dan Margulis"


So, Howard, if you really do have prints that show the beneficial effect of
having been worked on in 16bit, then you could become even more famous than 
you already are! Just send Dan two prints of the same image, with the same 
treatments, one done in 16bit and the other in 8bit, along with the files 
for verification.

Bob Frost.

----- Original Message ----- 
From: "Howard Averbach" <haverbach@...>

>
> For what it's worth:  unlike photographers, whose
> camera output is likely "pretty good" to begin with
> and thus needing mere tweeking and croping, photo
> restorers like myself typically start with horrible to
> fair originals that need MASSIVE "Levels" adjustments,
> lots of "Cloning", and often extensive color and other
> improvements.
>
> In situations like this, ANYONE can see the
> significant improvement -- to the histogram as well as
> to the final output -- using 16-bit files as opposed
> to 8-bit mode.