A great example that illustrates the point that I was trying to make to Charles. Your muddy and dark print is a result of overall low contrast of your negatives, so I would suggest correcting the curves not altering pigments. This is exactly what you have done by printing more contrasty negatives resulting in a print with a lot of "punch". Remember that changing printer setting could change the "curve" (or should I say ink density) without strictly applying curve dialog in Photoshop.
Thanks for a great teaching example.
> Date: Tue, 25 Sep 2007 19:17:22 -0700
> From: firstname.lastname@example.org
> Subject: Two tricolor prints
> To: email@example.com
> On Sep 25, 2007, at 4:54 PM, Katharine Thayer wrote:
> > I'm struggling with a similar issue, but finding that I have a
> > different problem than many people have reported. After happily
> > printing tricolor gum for decades by simply inverting the channels
> > and printing greyscale separations, I've been experimenting with a
> > more "sophisticated" approach, with less than satisfactory
> > results. But the problem isn't that the print is too dark when the
> > colors are layered over each other, it's that it's too light and
> > too muddy, compared to the same image printed with the same
> > emulsion by my old habitual method of simply inverting channels
> Here's a comparison of an image printed from the colorized and
> calibrated separations, and the same image printed from separations
> made by simply inverting channels and printing without further
> manipulation . The jpeg is rather small because I was intending to
> append it to a post on another forum, but since the question of
> calibrating tricolors came up here in the meantime, decided to just
> put it up on my site; at any rate it's not necessary to see detail;
> the difference in the vividness of the color, which is the issue of
> note here, should be quite apparent even in the small images.
> I named the page rather cockily "If it ain't broke..." but it is a
> little broke in fact; the greyscale separations can make a print
> that's too contrasty, which is the reason I decided to see if I could
> get an improvement with colors and curves. But so far, I'll take the
> straight inversions even with blown highlights. This isn't just an
> anomaly; I did several prints with different pigments and proportions
> and got the same cloudiness on all of them.
> I've been thinking for a while of switching to Prussian blue for
> tricolors, and these are my first prints with Prussian; it will
> definitely be my blue of choice for tricolor from now on. I'm still
> playing with pigments and proportions to balance the Prussian, but
> the combination I used here gives a fairly close approximation to
> the original colors.
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