The limiter limits exactly to the patch (or in between even in this case). I have verified this precision over 100 times. So something is off elsewhere.
Just use the normal curve and the new curve and blend between them to get the correct density.
best,
Walker
Thanks for the input Walker. I am sure you have indeed verified things on your side, that is certainly your area of expertise.
Unfortunately I have no way, since I am on a PC, to “blend” the two curves, unless there is a tool I am not familiar with.
I would also prefer not to compromise and start messing with correction curves in PS especially since I plan on using PiezoDN and QTR for other alt processes. A .2 error is significant in any of the alt processes. Why might I be seeing a discrepancy between your curve adjustment and my output? While I admit a mistake on my side with the wrong ink, I am relatively certain all else is normal at this time. I do have some experience with QTR, truthfully never really liked it, but it is what the world uses. Are there any other setting in QTR I may have overlooked. I am using a unidirectional print at 2880 super. FYI, my densitometer measures favorably against two Stouffer calibrated wedges so I can most likely rule that out.
Sorry if I am waring you out. 
marty
Ah, I see I can spit between two curves in QTR. That is how I can blend. Hmm, so I would add a bit more in the shadows from the gravure-pos to build up the density in the blacks. This might just work and give me the flexibility for change as needed.
Any tips on blending curves in the world of positives?
OK, guess I am on my own at this point. Yes?
Blending is as simple as moving sliders left and right. Re: copperplate, you are probably the only person doing (or needing) this blending for that process specifically. The usual methods of testing apply: choose three blends, print the densities, and dial to the one that works.
best,
Walker
Hey Walker,
Yes, I sort of figured that out and am on my way to a practice resist exposure and etch test to where I stand. The process is very workflow dependent and can vary greatly from practitioner to practitioner.
Optically my step wedge 0% to 100% ink coverage looks pretty linear and now has a 1.26 DR with a blend of 4% in the shadows between Curve 1, the Dragon-Gravure-V3 (at 96%) and gravure-positive (at 4%). The density measurements look consistently linear to what I was reading when using CFP inks and Phoenix Gravure Tissue.I will post actual density information if anyone is interested.
I do have TWO questions.
I only manipulated the shadow blend and will ultimately see how that tests in practice. Should I have also added some midtone blend? I will ultimately see when a print is made, although as I stated previously the densities are reading linear and optically the gradation looks smooth.
I do not doubt your accuracy for the V3 Curve but am till perplexed as to why my printer was off by 0.2 in the shadows. My printer is outputting very consistently. Is this just a manufacturing variance between printers or is there possibly some sort of issue I have overlooked. This is important to me as the 1430 is going to be the anchor for other negative testing I will be doing with the PiezoDN system. I so not want to build a workflow against something faulty or incorrect.
Your input is appreciated.
Marty
Hello Walker et al,
Here are links to 2 recent prints using PiezoDN and Cape Fear Press Dragon Carbon Tissue.
The positive relative to the etch/print shows promise.
The DR of 1.3 is good as shown on the Stouffer scale included on the Delphi Test. Step 10 at 1.3 is perfect. The shadows on the QTR cure are well matched in a blended curve. The curves were both supplied by Walker. The DR for the positive is 1.3. Step wedges were printed with both tests and Delphi was printed with the PiezoDN limiter target. Both test conclusively showed lack of separation in the mid tone and highlights. The proximity of similar tones is noted with the red bars on the image. The lack of separation shows clearly on Delphi and in muddy midtones. The etch was not linear over the red groups, very quick etch progress.
I imagine what needs to happen is the curves need to be combined and linearized. I am on a PC and do not think I have the needed tools to do this. Advice/help please. The plates and prints show a fair number of defects but fine for testing.
Thanks,
Marty
You’ll need to use a spectrophotometer in order to calibrate. Other than that you are all set. This is a requirement of PiezoDN/Calibration as stated in the download.
best,
Walker
Also, after getting a spectra you will need to take the 21step target and place 7x of it on a canvas in photoshop and print this. Then average the 7x measurements. Ink wiping is not a precise thing so one target will not work. You need to do it several times on the same plate. Use the third print from the target “edition” too as this will ensure a fully inked and “running” plate.
best,
Walker
Hi Walker et al,
Thanks for the follow-up. I have been reading over the instructions, combining both the “short form” and the manual. I think I know the next steps but let me innumerate so I do not screw up.
Print out the 129 step scale for the i1pro, this is as per the instructions, but you are indicating I should just go with the 21 step? I have a i1Pro (aka iPro1) and assume it is not a iPro2 by the designation on the front of the spectophotometer?
Print out the step scale using the curve blend that gave me a solid 1.3 (± 0.02).
Expose the carbon tissue using the exposures I had previous success with.
Etch as best I can to achieve a full scale etch.
Print making sure inking is complete. Yes generally it is the 2 or third inking that gives good coverage and solid blacks. You definitely have a terrific knowledge of the photogravure process understanding inking.
After letting the prints dry for a day or two read with the i1Pro. This is where I am a bit unclear. I did download the Colorport 2.0 utility but do not see a option or know how to create a option for the 21 step scale or 129 step scale depending on your response. Am I overlooking something?
I now assume after scanning with the iPro1 that data file will load it into the PiezoDN 21 Step or 129 step scanner file to complete the linearization. Does this data self populate or is it manual entry. Densities need to be entered for L, A and B. Oddly the CGATS tab on the 21 step utility shows 129 places. Is this correct? Please verify.
This is a pretty exciting step and with a bit of luck will get me closer to consistent and repeatable results than ever before.
Thanks,
marty
Yeah. You need to print the 21step target multiple times and measure multiple times and average these in Excel. At CEP we do this with a 7x100 step target but with the DTP70 which takes smaller patches. I have not completed the 21step but just cut/paste your film onto the plate for exposure.
You really need the PPEv2 software for this. PeizoDN (base tools) aren’t built for gravure calibration. PPEv2 can take 21step, 23 steps, whatever between 21 -> 256.
-Walker
Hey Walker,
This has turned out to be more complicated than anticipated. Looks like I have to bite the bullet and get the PPEv2 software? I suppose in the long run the software will be beneficial for this process when I get finally get my arms around it and for future endeavors with other processes?
I am not entirely clear about this statement: “You need to print the 21step target multiple times and measure multiple times and average these in Excel.”
Are we talking about the positive for printing or the printed gravure? I assume you mean the printed gravure? Am I manually averaging the measurements and entering these manually?
I am also not clear on this: “I have not completed the 21step but just cut/paste your film onto the plate for exposure”.
Do I just print out this target with my current curve blend and expose the positive to the carbon tissue and etch as usual (as I am sure you are aware this varies based on a wide variety of factors)? I assume the target will read appropriately with the PPEv2 software?
I am also assuming by using the PPEv2 software the readings from the i1pro 2 (turns out this is what I have) will populate into the linearization software automatically?
Sorry to be full of questions but this is pretty much out of my wheelhouse and I am at the point of no return now with a serious investment in materials and time.
Thanks,
Marty
Any input Walker on my previous questions?
Thanks,
marty
You have a few options going forward.
You can print this target below and get an icc made to your specs by us for $100
Piezography-700step-DTP70.tif.zip (2.0 MB). (If you go this route do not print the color targets on the product page linked above. Print the tif target I just uploaded exactly to size as a gravure and send us the third print.)
You can take our gravure workshop where we teach this icc process.
You can purchase PPEv2, and modify the 21step target yourself, figuring out the 21step averaging method, and create the ICC using that process.
What I provided in this thread was a beginning curve and a direction pointer to finishing the process. What I can’t provide is the entire workflow or full labor in teaching you how to do everything. That is what we have workshops for. PiezoDN does not include any official gravure workflow. Nor does PPEv2 however plenty of people are now using the monochrome ICC profiling of PPEv2 to get gravure working in their studios.
Best,
Walker