linearization of a .quad - newbie questions


#1

Hello! I have the PiezoPro inks loaded in a 9800 and am trying to linearize a supplied quad file for the first time.
Epson Hot Press Natural
Using Colorport and i1Pro2.
Printed and read and input the 51-step charts ok. Now at the 129-step stage. Starting with the ‘Cool’ curve. Attached below is screenshot showing ‘error corrector spreadsheet’. I had a number of ‘falses’ which I manually corrected in the ‘L’ column.
My first question is, what is best recommended practice for correcting falses? Should one enter a number that is equidistant between value above and below? Or should one be trying to match value the is supplied by graph to the right?
Second question, is the below linerized curve looking acceptable? The shadow areas are slightly too dark and the mid tones slightly too light. But is that variance within ‘acceptable’ range? are these imperfections within human sight/worth worrying about?
Third question…the final step in the process is to drag both the new txt file and the quad file into the QTR-Linerize-Quad app. But which quad file? The original quad file supplied or the new quad file that I have created based on the 51-step target? I would assume the ‘new 51-step’ version because that is what I have used to print the 129-step version but I just want to be sure I am understanding the process properly?
Many thanks as always
Neil


#2

Hi Neil,

In my early days with Piezography Pro I had many of the same questions regarding the linearization process. After getting through my learning curve, I made up the attached sheet that should help clarify your third question regarding “which quad file” to use for the second pass of linearization. You should use the “new” temporary quad file that was created from the first pass, i.e. the “output” of the 51-step linearization. Hopefully my diagram will make it clear.

Regarding your first two questions: Luckily I’ve never had any false values needing correction (I also use a i1Pro2) so I don’t have any personal experience to give you guidance. I’m sure Walker will have a comment on this. The curve itself looks fairly reasonable to me for a first pass; hopefully the second pass will improve on it.

Dave

[attachment file=30551]

PP-Linearization-Process.pdf (177 KB)


#3

Hi Dave
Thanks for this! This is great, will definitely add your chart to my ‘working notes’!
Much appreciate the time and help
Best
Neil


#4

This is the curve prior to correcting the ‘falses’


#5

Looking at the curve you in-fact do not need to linearize more. That is good enough.

The bottom measurement error was just a slip of the spectro probably but you still don’t need to linearize.

best,

Walker


#6

Great thanks Walker
For future reference, what is best recommended practice for correcting ‘falses’? Should one enter a number that is equidistant between value above and below? Or should one be trying to match value the is supplied by graph to the right?
Regards
Neil


#7

Equadistant(ish). The tools smooths it a bit from there as well.

 

best,

Walker