Re: How to apply curves in PS for digital negatives...

From: Yves Gauvreau ^lt;>
Date: 11/28/05-08:38:39 AM Z
Message-id: <01bf01c5f429$6e840730$0100a8c0@BERTHA>


I don't have Dan's book but one thing is for sure, there are so many
variables in play from the original to the final print that I would be very
surprised if you could use someone else curve just like that. I strongly
suspect as others have said that you need to derived your own test not only
for a specific process but each time you use a different material from what
was tested.

There is another way one could find to produce a proper workflow for a
particular process, that is creating a fine tuned color space to produce
your negative. But this can be relatively more complex and it would still be
limited to the materials used in creating it. The possible advantages would
be more precise control, use of color mode to produce negatives, most
probably better control over color separation negatives and other stuff I
can't think of at this time.

But again, all this is very nice and playing with numbers is relatively easy
but even if you are "scientific" about producing your images it wont help
that much in producing "art". For exemple Ansel Adams said that a polariod
52 produce one if not the nicest tonalities he as ever seen and this
material is far from linear. In other words, it may be better to get a less
"objective" transformation and more pleasing results.


----- Original Message -----
From: "George L Smyth" <>
To: <>
Sent: Sunday, November 27, 2005 3:38 PM
Subject: Re: How to apply curves in PS for digital negatives...

> Yves -
> Yes, these are things I understand. I must admit that I've got Dan's book
> simply have not had the time to get through it. I am hopeful that when I
> (hopefully I will have time in December) then that will get me going in
> right direction.
> I figured that I probably was understanding something wrong so I applied
> curve to the positive and made a digital negative, then applied it to the
> negative, then making a digital negative. The result with both was to
> contrast, as expected.
> I would love to be able to apply a curve to a negative that works in the
> darkroom, as that would open up so many things for me.
> Cheers -
> george
> --- Yves Gauvreau <> wrote:
> > George,
> >
> > One thing that could help you or not, I don't know. When you look at an
> > image on the screen you have to understand that this is most probably
not a
> > "true" representation of the actual numbers in the digital file, it's an
> > interpretation. When you print it on your electronic printer, again you
> > another interpretation of these same numbers. Say this print is your
> > negative, then if you use it to make a paper print it is kind of using
> > other "machine" that gives yet another interpretation of these numbers
> > again.
> >
> > You may see the curve you use as kind of distorting the screen
> > interpretation you see such that your negative "should" produce a print
> > ressembles more closely what you see on screen. You must not forget that
> > your eyes are also interpretting these "number" in there own way.
> >
> > All this is because the "number" are never precicely translated or
> > interpreted in what is called a linear transformation. I would agree
> > anyone saying that electronic interpretations can be very close to a
> > "perfect" linear transformation but I would say not "absolutely perfect"
> > very very close.
> >
> > A possible reason why you don't get "an acceptable digital negative"
> > be that the curve you use was design to be applied to the negative or
> > positive and your using it the other way around???
> >
> > In the end, if you have at minimum a mean to read back the output of the
> > process, (screen->neg->paper print) you could find out the "exact" or
> > I say one of the most useful transformation to use (a curve or other
> > for printing your negatives such that they give you the result "you
> > The most important aspect here is that you will get a reliable and
> > consistant mean to produce your negatives and or prints. All this stuff,
> > however presicely it can be achieved, wont be the determining factor in
> > producing a "masterpieces" or just a plain image, sorry.
> >
> > Yves
> >
> >
> >
> >
> > >
> > > I guess where my misunderstanding lies is that the curve for Van Dyke
> > removes
> > > some of the contrast of the image. I definitetly need to increase the
> > contrast
> > > to make a proper Van Dyke image. I have yet to get an acceptable
> > > negative, but continue trying.
> > >
> > > Cheers -
> > >
> > > george
> > >
> >
> >
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Received on Mon Nov 28 08:39:45 2005

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