2015-12-09 by richard@...
It looks like you ink limits for that paper are way too high. You should start with each one around 60, and maybe a K boost of 75. I tend to stay around/lower than 64 with Platine and baryta papers, with a boost of 72. It makes it nice and dense without causing problems with the other steps.
The ink limits are just a percentage of the total of what the printer is capable of printing at the 100% patch (or k%). If you set the ink limit to 60, then each of the 5% patches in the ink separation image is remapped as a percentage of 60 (ex the 50% patch is 30% of what the printer is capable of printing).
You can determine what the proper ink limit is by looking at the coverage of the printed ink separation image and where it looks like the density stops increasing regularly. That can be the limit for all three of the channels in the UC-K3 ink set. You can set the K_BOOST to 5-10 more than the K limit to get a little extra density at the very end of the scale.
I prefer to measure each patch of ink separation image with an i1 Pro in strip mode with i1 Profiler. I have a template that automatically graphs it so I can see where these densities level off and so I can define a Dmax I want to reach and easily identify the optimal ink limit.
I don't know if your color munki can do that with format of the measurement targets for that device (personally, I would sell it and get a used i1 Pro). You should measure the ink separation image for K, LK, LLK to get the correct cross-over points (or make a really good guesses and deal with any bands in gradients or failures to linearize when you get to those later steps).
When printing the 21-step targets you should do it without color management first. Then once you get the profile linearized you can test it to see what works best for you. Here is how I see it though: If can you make good linear profiles for glossy papers I would just leave the working grayspace to 2.2 and print with PrintTool with no Color Management or System Managed, or through Photoshop with "printer controls color". Matte papers are a different issue and I have my own way of modifying the curves for those. I'd stick to Piezography for matte papers, and usually tell people to just use Jon's recommendations.
I am not sure why the Raw Neutral profile print linear without linearization without seeing the measurement file and graph. Can you post it or send it to me privately. I might be able to take a look at it later this week or over the weekend.
Hope that helps,
Richard Boutwell
---In QuadtoneRIP@yahoogroups.com, <unesco18@...> wrote :
Hi all,
I try to make my very first curve for some baryta papers qith QTR and newly purchased Color Munki spectro (for 3880 with Ultra Chrome VM inks).
Made separation page, set default ink limit to 75, measured relation of LK and LLK to K and then problems appear.
1) I do not fully understand Ink Limit term for each channel and how to set proper values. Is it somehow measurable? of just try-and-error? I have read number of documents, but haven't found satisfactory answer.
I also tried built in curves: UCpk-raw-neutral and tried to linearize it. Strange thing: curve without linearization looks to give perfectly linear printout (or at least smooth). When I put linearization results (L measured), the bull-eye has clearly visible bumps.
2) Does anyone ghas an idea about the reason?
3) Shall I use 21 steps as in QTR catalog (i.e. without built in color profile) or evenly L spaced one with Gray Lab color space?
4) What should be default built-in profile for BW picture printed to make it linear and suited for QTR and the whole curve creation and linearization process (Gray Lab, GG1.8 or 2.2)?
I can't move forward with my exercise withour knowing the answers - another one printer (1400) also waits for its curves and future Piezography :-).
Any help highly appreciated!