Hello
I’m trying to limit my negative density using PPev2 but the video tutorial is not too informative and on the instructions the only information is for PiezoDN, where I can find more detailed information of how to do it using PPev2?
Thank you
Moises
The instructions for limiting using the Curve Adjustment Tool in original PiezoDN applies to New Curve Output Contrast Tweaking section of PPEv2. The only difference is that (same as with any new curve) in PiezoDN you have to use QTR-Linearize-Quad to actually create the new curve, while in PPEv2 you just copy the New Curve as per the instructions.
Just follow the procedure in the manual but using Contrast Tweaking and you’ll be golden. Remember to put your Starting Curve in, but do not put in any measurement data. Shape the new curve with the 5 points exactly as you would in Curve Adjustment (except that you have 5 points rather than 4). Instructions for saving the New Curve are at the top of that tab in PPEv2.
Another option is to use the Start Points section of PPEv2 and set the highlight point to the new value determined from the results of printing the Limiter target, but this has the side-effect of lowering Step 1 density as well as everything else, rather than from step 2 onward. You could then go in and manually restore the higher step 1 density in the K channel, which I have done when using this tool.
I also remember Walker once musing on the possibility of having a check box to do that — maintain the high Step 1 edge masking density, maybe it wasn’t possible to implement that idea.
If you still don’t understand the process (which is not uncommon when you haven’t done it before), post the result of your Limiter print and I’ll walk you though it step-by-step.
Keith
Dear Keith
Just did it without any problem using the tweaking curve, as your instructions.
I have 1 question, when I enter the measurement values from my print and the limited data curve data (pn the second round) , should I leave the tweaking points as original (linear) or should I enter again the tweaking points from the limited values?
Thank you!
Moises
I knew I was leaving something out that I meant to mention!
Set the tweaking points back to linear. You have just created a custom limited starting curve (or Master curve if you like).
In the next phase — linearization — you will begin by making a target negative using the New Limited Curve that you just made. Print that in the darkroom, read it, then go back to PPEv2, clear any contents that may be left there, enter the Curve you made the negative with in the Starting Curve tab, enter your measurements in the Measurements tab, and save the results from the New Curve tab.
Repeat this process to verify the linearization. Make further adjustments if necessary.
Keith
I was almost sure of that, but didn’t want to make a long mistake in the darkroom 
.
Thank you again for your help.
Best
Moises
Keith
What’s the difference between the measurements tab and Target measurements tab?
Thank you!
Moises
Keith
Should I make different curves for each developer?
Moises
The Target-Measurements tab is for matching this system to another system you may have used previously.
See the Target Luminance Matching section on this page for an example. https://piezography.com/about-piezography-professional/
I have used it to make a digital equivalent of a 21-step Stouffer step tablet with steps at 0.15 density increments. It wasn’t easy.
Target-Measurements is for very specialized purposes and not something to worry about for routine linearizations. Use the Measurements tab.
Keith
Almost certainly you should make different curves for each developer. Ammonium Citrate tends to be a bit contrastier than Potassium Oxalate. Do the oxalate linearization first, then print a target with that curve, print it in the darkroom and develop with citrate. Most likely it will be a bit contrasty, but not so much that it can’t be easily linearized using the standard method (i.e it won’t need to be limited.)
If you use different papers or different ratios of Pt and Pd you may want to make a custom curve for each variation. Alternatively, you could use a single quad curve and make a custom ICC profile for each variation to be used with that quad curve. We have options!
Keith
Sounds good!
Thank you Keith!
Best
Moisés