For those who are interested in trying Paul’s curves out, here are some notes on my experiences, and why I’m currently using them rather than profiling from scratch.
I’m using an Epson Artisan 1430 with Quadtone RIP, and I mixed my “Eboni Variable Tone” ink from scratch using Paul’s formula and Eboni 1.1. Note that for the blue toner in the Y position I used a 75% clear base and 25% blue mix instead of 90% clear base and 10% blue mix. This required changing the Ink Limit for Y from 30 to 12 in Paul’s generic curves (which are designed for a 90% base in the case of the 1430). For each curve and paper, I linearized independently using a spectro.
Importantly, I use Lightroom in a color-managed Windows environment, and I don’t have Photoshop. See the end of this post for why that matters if you’re in the same position.
I made “neutral” and “warm” versions for both papers. The warm version is based directly on the neutral curve, with the only difference being that Y (the blue tone) is not used and the curve was re-linearized.
I experimented quite a bit with the limits and densities, but in the end the curves supplied by Paul worked best for me with their original parameters (except for Y, as above) and of course linearization. As a side note, Paul’s generic curves seem to be very robust; in my testing, they responded to changes in limits and densities, but never “broke”. This may explain why they work so well for me “out of the box” on the papers I’m using.
I now have excellent neutral and warm curves that, when used together with QTR’s sliders let me adjust for the exact tone I’m looking for in a print. Split toning also works very well, especially because the curves are identical except for the Y ink and slight differences from linearization.
It’s fair to ask “why not make a curve from scratch for each paper”. If you have the skills and the equipment, then that’s a great option. I have the equipment and my skills are getting better… but the learning curve is mighty steep! For people who want to focus on printing photographs, rather than diving deep into QTR profiling, curves like this are a great solution. If you can figure out how to linearize, you’ll be up and running in short order. It’s not quite a turnkey solution, but it’s a lot simpler than starting from scratch with each paper and ink.
Technical note for Windows Lightroom Users
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I wasted a lot of time adjusting limits and densities on Paul’s curves because my prints were coming out flat and dull. I thought the curves were the problem. The issue actually was the way I was generating the TIFF files. In a Windows environment, using Lightroom, you have to export a TIFF image that you then print using QTR. I was exporting my TIFFs with the Adobe 1998 color space, which is a curved space. QTR uses a straight-line colour space. For Photoshop users, it’s easy to deal with this: apply Paul’s GG22-to-QTR.acv curve to a TIFF file created for printing with QTR and you’re good to go. I don’t have or use Photoshop, so I need a Windows Lightroom solution.
I posted in the QTR forum explaining the issue and how I deal with it now (but my solution still feels kludgy so my post is seeking advice!) If you have a good Windows Lightroom solution, please consider responding to that posting so that others in this situation can follow.
https://groups.yahoo.com/neo/groups/QuadtoneRIP/conversations/messages/13420