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

From: George L Smyth ^lt;glsmyth@yahoo.com>
Date: 11/27/05-02:38:24 PM Z
Message-id: <20051127203824.81578.qmail@web33203.mail.mud.yahoo.com>

Yves -

Yes, these are things I understand. I must admit that I've got Dan's book but
simply have not had the time to get through it. I am hopeful that when I do
(hopefully I will have time in December) then that will get me going in the
right direction.

I figured that I probably was understanding something wrong so I applied the
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 lose
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 <gauvreau-yves@sympatico.ca> 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 get
> 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 some
> 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 that
> 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 with
> anyone saying that electronic interpretations can be very close to a
> "perfect" linear transformation but I would say not "absolutely perfect" but
> very very close.
>
> A possible reason why you don't get "an acceptable digital negative" could
> 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 should
> I say one of the most useful transformation to use (a curve or other means)
> for printing your negatives such that they give you the result "you want".
> 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 digital
> > negative, but continue trying.
> >
> > Cheers -
> >
> > george
> >
>
>