Ink limits for setup/linearisation?


#1

Hi. I have recently started linearising my first piezo pro curves for my different media on a 7900. I have followed Walker’s advice in a different post of using Canson Baryta as the master for glossy media, and I believe it was Hahnemuhle Photo Rag as the master for matte media.

Initial 51 step target for glossy media looks great, but on my matte smooth fine art paper (Breathing Color Signa Smooth), the last black patch ink looks too heavy (it is darker if viewed from some angles, but at other angles there is a change in reflectance characteristics / gloss differential, and it appears lighter than the previous patch). Also, on many of the other darker-mid grey patches especially there is visible mottling or dot noise, not a consistent smooth tone. (In comparison, my color profiling patches for the same paper on an older Canon printer are totally smooth).

So my suspicion is that the Hahnemuhle photo rag quad curves are giving it more ink than it can handle, and it needs to be dialled down a bit. What is the best way to experiment with that (unless there is a different issue going on)?

I’ve noticed the QTR driver has a checkbox for Advanced Adjustments, and an ink limit slider (Mac version). Would this be the proper tool to use, while retaining the specific characteristics of the piezo quad curves? Or is it better to somehow directly edit the figures in the quad curve (I suppose by running a multiplication factor formula in excel?)

BTW, I am using all the recommended settings (2880, unidirectional). I have tested and adjusted feed values for each of my papers, paper thickness settings, and head alignment (which did seem to help a little). Nozzle checks were clear before printing. Just in case there was an issue somehow with the matte curve itself, I tested that on glossy paper and there was no noise/dotting issue on that media.

Sorry for the long post, just trying to cover all the bases!

Thanks for your help.

Jeremy


#2

Hi Walker.

I never got a reply to the above, so I’ll try resurrecting this again. I have now linearised all my media, using the Hahnemuhle photo rag quads as a starting point. (I’m using a 7900 with Piezo Pro Pro-K4 inks/Curves)

My Breathing Color Lyve Canvas shows something like gloss differential at full black. It is a matte canvas, but 100% black has quite a sheen to it, which picks up when the light is glancing on it at a bit of an angle. My Breathing Color Signa (smooth matte paper) is similar.

So I’m presuming that the black is being over-inked. To test this, I experimented by creating a set of patches using Lab figures of 0%, 1%, 2%, etc. At an Lab setting of 1% most of the glossiness is gone. (I’m guessing this is ink sitting on top of the paper instead of being absorbed?)

I also tried printing a problem image (with some blocks of pure black), using a photoshop curve to increase 0% Lab to 1%, and that showed a marked improvement with the reflectivity of the over inked areas.

So my question is: What is the best method in Piezography that to limit the black ink?

Thanks!


#3

Please ZIP the curves used and measurements from the over-inked (reversed) prints. I will look at the data the post properly limited curves and then others on this forum can use these curves for paper that doesn’t take as much ink as normal.

Sorry for no reply. I have been teaching.

 

best,

Walker


#4

Thanks Walker. I’m attaching the zip file here. I have also emailed your gmail account and the techsupport email with the zip file if this doesn’t work.

Inside are linearised warm and cool quads for the Signa Smooth (fine art cotton rag) and Lyve (canvas), linearised from the Hahnemuhle photo rag quad. There is also an excel spreadsheet with measurements of 5% increments from all the inks in calibration mode.

Visually I’ve deduced that black (and total ink) limit for the Signa shouldn’t be above 65%, and the Lyve canvas even lower (50–55%). Above those values I start seeing a reflective sheen in the blacks when viewed at an angle. I’ve also noticed in the other inks (the greys) on the Signa that values over 65% start appearing noisy/grainy. Looking through a 10% loupe it seems the ink is pooling/settling in the troughs in the texture of the paper and appears darker there than the high points.

Thanks for the help!

Jeremy

InkLimits4Walker.zip (26.7 KB)


#5

Thanks Jeremy. I think you are ready for the updated QTR linearization and limiting tool (part of Beta driver but soon to be part of PPE as well). This will allow you do to a much finer limiting of the TIL where not just over-all but in particular points along the tonal scale. This is needed I think as I’m looking at the 100% K ink levels and they are in-fact reading good (L13+ etc) where-as most likely a combo of lighter inks + K are making a sheen. You’ll need to limit those tonal areas more than the last point (L0) and doing this remotely will not be helpful.

Please apply here so I can keep your details on record. The second the email comes through I will give you access: https://piezography.com/piezography-driver/

I will also give you access to the beta forum here: https://community.inkjetmall.com/c/beta-tester

best,

Walker