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

Just remember that 'how the curves look' is completely immaterial. The point
of the curve is to map the values on screen to appropriate densities on the
output negative. Printers and printer drivers can all do different things. For
instance, a particular printer/driver combo might create more contrast than is
desireable in the shadowed areas of the image, thus requiring a curve
to 'reduce' the contrast on screen so that it gets mapped correctly to your
output substrate. Or the reverse could be true. It all depends on how the
particular printer/driver pair do their business.

No one can look at the curve alone and declare authoritatively that it is crap
without knowing the printer, the printer driver, the inkset, the output
substrate and the printing processs being used.

Clay

Quoting George L Smyth <glsmyth@yahoo.com>:

> Joe -
>
> Since I am at work I could only take a quick glance - I will print them out
> tonight. However, your curve looks much closer to what I was expecting to
> see.
> The curves at the other site showed that the author was decreasing contrast
> and you are increasing it (I see the "S" curve).
>
> Unless someone has a VD formula where a "normal" negative needs a reduction
> in
> contrast (I doubt it), I cannot see how the other curves could possibly
> work.
>
> Cheers -
>
> george
>
>
> --- Joe Smigiel <jsmigiel@kvcc.edu> wrote:
>
> > George,
> >
> > You might find the following web pages of interest. They summarize some
> > tests I ran last year for double-coated Van Dyke Brown printed using a
> > digital negative generated in Photoshop and output onto Pictorico OHP
> > using an Epson 2200 printer with Ultrachrome inks and printed onto
> > Cranes' Kid Finish stationery. Be forewarned of nude content though.
> >
> > http://my.net-link.net/~jsmigiel/images/technical/vdb_test_11-19-04.jpg
> >
> > http://my.net-link.net/~jsmigiel/images/technical/VDB_test_prints.jpg
> >
> > The pages show before and after curve adjustment pics as well as
> > positive/negative files, a graphical depiction of the curve applied to
> > the *negative* image file, a table comparing %K values after curving
> > and resultant transparency density, and a couple of final prints scanned
> > for comparison of two slightly different curves. There are also digital
> > density step wedges, both affected and unaffected by the curve
> > adjustment, as well as Stouffer 21-step wedges printed along with the
> > files.
> >
> > Prints were processed in Kalamazoo municipal water using a 2% citric
> > acid initial wash and gold-toned using Clerc's gold-toner after fixing.
> >
> > :)
> >
> > Joe
>
>
> Handmade Photographic Images - http://www.GLSmyth.com
> DRiP Investing - http://DRiPInvesting.org
>
>
>
>
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Received on Mon Nov 28 12:55:44 2005