Jagged Curve - should I smooth?

Using the PPE tools to make Digital Negs for Platinum. After tightening the process and working on linearizations, I am getting this. The linearization shows that I’m a little dark, but not too far off.

But what is going on with the ink channels? The jagged shape near the highlight end seems strange. Should I use smoothing to iron these out? If I do, it really seems to affect what is happening in my highlights

Second question: Does the light grey line represent the ink channels from the original curve and the dark grey represent the ink channels for the new linearized curve? I can’t see any notes on this in the manual. Makes it hard to interpret what is going on.


Hmm. May be a slight bug. Save this .xlsb file, zip, and send me a private message of it so I can take a look. But in general this is a perfect linearization. The reason why it’s showing “dark” on this one is because the last print probably had a slight bit of fog or darker paper white.

Look directly below the graph at the color legend and you will see your answer . . .

Thanks Walker. Just sent a .zip file via email…

Hi Walker, did you manage to take a look at the Xslb file?

I’ve been using the original starting curve, but each time that I do another linearisation I get a similar result with a little jagged moment on the K curve very near the highlight end. I don’t want to use the new jagged curve - should I just replace the "bad " value in the curve with a new one?

I don’t have it yet. Please zip the xlsb again and email


Hi Walker, I sent the file again. Did you get it last week?

Also here now as a link using my wetransfer:

Let me know if you can look at it.
Thanks again

I am on MacBook M1 with most recent Excel.

I don’t see the issue:

but then again, it’s not the same measurements as your screenshot above . …


My fault, wrong XLS file. Sorry!

Here is the curve I am working with, jagged endpoint, new curve shows reversal in K channel near highlight end.

Removed after download:

solution: make the top = to just above the second number.

Screen Shot 2021-02-22 at 6.44.59 PM

It has to do with some basic math stuff that I’m trying to figure out. Like, how to automatically detect this strange divergence of the top #.