Understanding the Error Corrector Tool


#1

For Canson Platine, I’ve now done three linearization iterations (51-step, 129-step, 129-step a second time) as I try to improve a bit on some very slight banding in a very smooth gradient on my test image (using Dual K4 on my 7900). I’m trying to understand something I’ve observed in the output from the Error Corrector Tool…

Here’s the Cool data from the first 129-step execution of the Error Corrector Tool:

[attachment file=27124]
You can see that there is a shift darker in a good bit of the curve. To try to get this a bit closer to the target linear state, I printed a new 129-step target with my linearized quad, read the data and did another iteration through the Error Corrector Tool. Here’s what I got:

[attachment file=27125]
Now you can see that the Error Corrector has produced a slight shift lighter in the same portion of the curve.

What causes this? Or maybe a better question is what are the factors that could contribute to this? So far my other papers (Canson Rag Photographique, Canson Baryta Photographique and Hahnemuhle Gloss Baryta have resulted in almost perfect matches between target and actual data. And interestingly, the Warm curve for Platine is also a perfect match. It’s just the Neutral and Cool curves for Platine where I see this. I understand that the measurement instrument has a certain amount of “jitter” in the readings, but I don’t think that would explain these two curves. Any thoughts?

Thanks, Dave

7900-K4-CPFR-Cool129.png

7900-K4-CPFR-Cool129b.png


#2

My thinking is that there is a dry-down factor that is effecting these inks a bit on this paper.

Was the dry-down time exactly the same for each target?

best,

Walker


#3

Yes, dry down sequence was the same: blow dry for about 10 seconds, dry overnight for about 24 hours. Studio humidity should have been pretty much the same in both cases. Same reading setup on my i1Pro2 table with the same reduced ambient lighting and i1Pro2 calibration before reading each target in spot mode for all patches (I’m very careful to be as consistent as possible when doing this kind of work).

Is there a difference in the drying characteristics of the Warm inks compared to the Cool inks? I ask that question because consistently I’ve noticed that my Warm curves seem to be right on target. If there is any variance off the target, it is always more noticeable on the Neutral and Cool curves. On the other hand, I’ve only noticed this swing from darker to lighter on the Platine. Maybe it’s a combination of the Platine and how it reacts to the Warm vs. Cool inks??

Would it be worth doing another 129-step iteration and letting them dry for say 48 hours?

Thanks, Dave


#4

I’m wondering about this dry-down effect with the Piezography inks.

When does the drying down actually end? Is it better to let the chart sit for two days,or a week? The hope is to get a reading on what one’s prints will look like for the long run, not just for day 2 of their lives.

 

Thanks,

Mark


#5

I generally let it dry down for 2 days if possible but the L* shift between 24hrs and 48hrs is only .1 at most so it’s not a big deal.

Looking at the graphs above it almost looks like you Lin’d the curve twice as the second graph is almost the exact opposite of the first.

-Walker