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.

I have learned a great deal from Dan's Professional Photoshop book and many
articles, but I've learned that I need to filter some of the things he says
about color management and 16 bit processing. The Bruce Lindbloom link below
describes a very significant flaw in Dan's 16 bit challenge. From Bruce's
home page click the Info tab, then scroll down to the "Dan Margulis 16-bit
Challenge - What's Behind the Controversy" article.

http://www.brucelindbloom.com/

By the way, I think the Bruce Lindbloom site is a treasure, though the going
is a bit rough mathematically. It not something everyone would be interested
in.

Steve

----- Original Message ----- 
From: "Bob Frost" <bob@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Wednesday, December 29, 2004 12:50 PM
Subject: Re: [Digital BW] was Copy of Photoshop 7 for Sale? now 16bit v 8bit



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.




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> From: steve_bye [mailto:steve_bye@...]
>
> I have learned a great deal from Dan's Professional Photoshop
> book and many
> articles, but I've learned that I need to filter some of the
> things he says
> about color management and 16 bit processing. The Bruce Lindbloom
> link below
> describes a very significant flaw in Dan's 16 bit challenge. From Bruce's
> home page click the Info tab, then scroll down to the "Dan Margulis 16-bit
> Challenge - What's Behind the Controversy" article.
>
> http://www.brucelindbloom.com/

I had a run-in with Dan about this in the Color Theory list, too.

Although I agree that most of the time, 8-bit processing is fine, there are
times where 16-bit produces visibly better results. You'll only see the
difference in a featureless gradient with very little noise, but in real
life such a subject is commonplace: blue sky.

To prove the point, I begin with a raw image from my Canon 10D, which is a
pretty quiet camera. I choose a well-exposed ISO 100 image of an outdoor
scene in sunlight, with a clear blue sky. To live up to Dan' stringent
requirements, I make a copy of the image, convert both to 8-bit, then
convert one back to 16-bit.

I then record a simple Photoshop action, using two commonly used tools.
First, I go into Curves, and introduce a very slight darkening to the image,
by setting the midpoint to (128,123). Second, I go into Hue/Saturation, and
tweak the Hue a tiny amount to +3. Third, I go back into Curves, and lighten
the image a tiny bit by setting the midpoint to (128,133). Finally, I go
back into Hue/Saturation, and restore the original color with a Hue value
of -3.

At this point, I stop recording the action, and replay it on the other
image. This produces no significant difference yet. However, if I replay it
a few more times on both images, and examine the sky, I see noticeable
posterization in the gradient in the 8-bit image.

Of course, this action involves two pairs of operations that more or less
undo each other, and then involves the repetition of these exact operations
a few more times. But the point is that it doesn't matter what the
operations are: any slight tweaks to the image in 8-bit mode will introduce
quantization errors, and it is these that can build up and become visible. I
only chose those particular operations to make them easy for anyone to
repeat the test, and to guarantee that the resulting image doesn't look like
it has been modified in some unreasonable or atypical manner. Anyone who
wishes to repeat this test can feel free to use any long sequence of minor
edits, using Curves, Levels, Hue/Saturation or Color Balance. I expect the
results will be the same.

I can provide the image I performed this test on, but the steps should work
on any image that has the characteristics I outlined: low noise, and a
properly exposed blue sky.

There are other ways, besides resorting to 16-bit calculations, to avoid
this posterization. For instance, one can use adjustment layers, so that the
back-and-forth tweaks don't pile up quantization error. This is a good
argument for adjustment layers, especially in earlier versions of PS where
full 16-bit support doesn't exist, but represents a restriction on workflow.
If you prefer just to tweak images back and forth until you like the way
they look, in 8-bit mode you have to worry that eventually you'll see a
visible increase in quantization noise. In 16-bit mode, you don't have to
worry about it at all. Since 16-bit support is present in Photoshop CS, you
might as well relax and use it.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...

Thanks for the information, Bob.  But whereas from
following these lists for years I know that you (and
others) are an accomplished photographer, I, as a
photo restorer, have several images where the
difference between working in 8- vs. 16-bit mode has
been astounding.

Now remember, I restore old photos -- lots of massive
"corrections", including the black and white points in
"Levels".  I have a B&W image from 1951, for example,
that I worked on within Photoshop 6 or 7 (I can't
recall which), but that I recently had reason to
revisit.

I rescanned the original image then worked for three
days to restore it, with Photoshop CS in full 16-bit
mode.

In Photoshop, the 8-bit version's histogram looked
awful (I'd be embarrassed at this today), whereas the
histogram in under the 16-bit version was very smooth.


In comparing the old and new print outputs (both from
my HP 7960 in grayscale mode), the difference was
significant.  The print that I restored in 8-bit mode
was MUCH grainer and exhibited significant small areas
of posterization (sp?).  In comparison, the 16-bit
version printed as smooooooth as a baby's butt
(without diaper rash).

I need to again note that we are dealing with a
restored 1951 image that required massive tonal
corrections, a "Multiply" blending mode, and need to
use "Curves" to improve contrast.

The only remaining issue for me is whether to now
keep/store such images in 16-bit mode, given how huge
the file sizes are.  Here is where I might agree that
since the major work has been done, any future work on
the image is likely to be limited to minor tweaks to
optimize printing for some future printer.  It is
unlikely that for such tweeks 8- vs. 16-bit would make
any difference.

That's my take.

Howard


--- Bob Frost <bob@...> wrote:

> 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.
> 
> 



		
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Paul,

I agree and I do.

But, that doesn't negate my original suggestion that PS Elements 3 is all 
that 'normal/ordinary' photographers need; the lack of 16bit working on some 
parts is not a serious serious problem for most photographers.

If you thought Dan's words sounded familiar, they were from your discussion 
with him!

Bob Frost.

----- Original Message ----- 
From: "Paul D. DeRocco" <pderocco@...>

 Since 16-bit support is present in Photoshop CS, you
might as well relax and use it.

Howard,

>I, as a
>photo restorer, have several images where the
>difference between working in 8- vs. 16-bit mode has
>been astounding.

So why not send your prints and files to Dan, and end this 16bit/8bit 
argument for once and for all time?

>The only remaining issue for me is whether to now
>keep/store such images in 16-bit mode, given how huge
>the file sizes are.

I keep mine in 16bit, ready for the next generation of printers that will 
perhaps be able to take advantage of those extra bits.

Bob Frost.

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