Katharine,
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.
Marek > Date: Tue, 25 Sep 2007 19:17:22 -0700 > From: kthayer@pacifier.com > Subject: Two tricolor prints > To: alt-photo-process-l@usask.ca > > > > 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. > > http://www.pacifier.com/~kthayer/html/tricolorcomp.html > > Katharine > >
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