Create Curve failure
2006-08-15 by Kevin Bradford
Well, I'm still trying to complete my first curve and I'm stumped again.
I created "UCpk-HahnFineArtPearl-Neutral.qidf" using "UCpk-IlfordSmPearl-neutralcool.qidf" as a template, see my profile for the settings I used. I kept the "Gray Curve", "Toner Curve" and, "Toner Curve 2" settings as they were but deleted the "Linerization" data. I then clicked on "Create Curve" and an Ink Curve graph appeared, confirming (I assume) that the profile had been built. Using this new QTR curve I printed the 21step.tif file with curve at 100% blend, 1440x1440 super resolution, better speed, and ordered Dither Algorithm.
An observation I made in creating this curve was that on page 18 of the QTR guide the author states that Cyan and Magenta inks are not used with UC inks and that Light Cyan and Light Magenta are used to create neutral tones. But in the Ilford neutral cool curve in the R2400 profile directory, the Cyan and Magenta are used at 100%.
When I viewed the 21step.tif print the darker steps seemed too warm and the lighter steps seemed too cold, but I did not understand how to adjust the limits of the individual tones to achieve a smoother tonal step tablet. I wonder if I am the only new rip user that is confused at how to manipulate the curve limits to achieve a consistent tone. The contradictory instructions and example files just don't seem to add up.
So I pushed on with my curve. I scanned the print (as I don't have a spectrophotometer or densitometer) to try and linearize it. When I viewed the scanned file in Photoshop using Adobe RGB color space I noted the Lab Color value of each step and added them to my curve. They were as follows from to top left to bottom right:
100, 98, 93, 87, 82, 77, 71, 65, 61, 57, 54, 50, 48, 45, 42, 37, 30, 19, 5, 1, 0
When I tried to "Create Curve" I received the following error message:
QuadProfile Report
Invalid linearize curve not constantly increasing
Curve Creation failed.
I am using a PC with Windows XP, Photoshop CS2 and version 2.4.2 of QTR.
Has anyone experienced this error or know what to do to fix it?
Thanks in advance.
Kevin