L*a*b* - a* values in the CGATS out file


#1

Easiest thing to do is look at the uploaded text file, but briefly: I’ve see this twice - scrolling down the list of 129 values, and looking at the text graph of Lab values, things look fine - sorta. The L* looks pretty much like it ought to, but I’m not sure how ab is supposed to look.

In the attached file, about 25% of the a* values about 1/2 way down, are jammed as far right as they can go.

My linearization of Canson AVMR doesn’t show that, but the Hahn Photo Rag, and the Epson Cold Press Nat both show it. I’ve scanned the data several times, and it’s always nearly identical. [ (Side note: The Hahn print seems a bit too open in the shadows, but that could be the paper. The Epson CPN paper has a -considerably- different set of curves from the other two, but then the -supplied- curve for it looks a bit odd in the first place, and my linearizations of it look to be in line with it (not too different.) ]

So: any comments on the “way right” a* values? Something I can ignore, or is it pointing at some issue I need to deal with?

 

EP-CPNcgats-out.txt (11.5 KB)


#2

Never mind. (HUGE exasperated groan goes here.) I got so excited about my new Pro subscription, that I did 80% of 5 different papers before I remembered that I did an ink cartridge swap because of a clogged nozzle in my 3880.

I was using the supplied .quad files, and did not go in and edit them for the swap first.

I’m going to take a couple of days off, to enjoy kicking myself around the block.

Interestingly, a couple of the papers look just fine, and had no hint at all of piezoflush. But when I got to the cheap papers… the red tone was obvious.

Sigh…maybe it’s because I’m turning 70 tomorrow…

I apologize for the wasted bandwidth.


#3

No problem! I’m glad it worked out.

best,

Walker