DO NOT OPEN NOR ADJUST THE TARGET FILE IN ANY WAY, NEVER, NOT EVER!!!
oops, I’m not supposed to shout here on the forum. But that needed a good shout.
- There should not be any color profile associated with any of the Piezography target images.
- They are originated without embedding a profile.
- They should never be converted nor edited.
- They are used purely for printing from QTR without any color management whatsoever.
Pure linear grayscale values are printed and measured and then later they are compensated for in the PiezoDN (or PPETv2) software to create a curve that produces the same separation of gray values and expectations can be met when printing digital negatives.
Digital images on the OS X side can be color managed during printing for several purposes. They can NOT on the Windows side. Windows QTRgui passes through actual grayscale values 0-255. OS X QTR can pass these through or it can be used to modify those 0-255 values.
There is only one method of printing with Windows and it does not include color management.
There are two methods of printing in OS X: Linear and the Contrast Match method which does include color management via an additional ICC profile.
You may need to download a fresh copy PiezoDN so you have an original target without any embedded profile. Then open the target in QTRgui and print it with our starting PtPd curve which is pre-limited. Expose, Process, Dry, and Measure. Create Curve. Open an image in Qtrgui and print it with the created curve. It should appear normal.
Anything different than this workflow may or will introduce unexpected results. You cannot calibrate for that with our system, and trying to adjust for that will disrupt the quality of the PiezoDN negatives.
How you image is different than how you calibrate. It’s not actually related. You image until it looks good. You save the file. It passes through on QTRgui. In OSX any embedded profile is taken into consideration because OS X is nosey and obtrusive. Therefore - PrintTool for OS X is mandatory now with QTR. There color management can be turned on or off and ICC profiles can be added to adjust contrast etc.
For you right now, start with the purist approach and then gradually add in variables one at a time until it is disrupted and back off or revert to a pure Piezography recommended workflow.
I trained on the PPETv2 tool and it is much easier than PiezoDN. Jon taught me to do it three times. The first target measurement from the starting curve roughs in the calibration and produces the first NewCurve1. The target is reprinted with NewCurve1. In PPETv2 Starting Curve is now NewCurve1 and the new measurements produce NewCurve2. Then NewCurve2 is used to print the final validation which should be really very linear. In PPETv2 Starting Curve is now NewCurve2 and the measurements if you find a little improvement is warranted create NewCurve3 or named as a final.
I was also instructed to Save a copy of PPETv2 for each calibration stage in order to keep a record of my “mistakes”. I find helping customers that that should be a standard practice. Keep all the copies and measurements in one folder under the date or media name or however you organize your workflow.
You can use contrast mapping in PPETv2. It is a manual adjustment to your final curve that will convert the linear curve into whatever contrast at the shadow end you prefer in order to produce prints that match your display. The pure linear calibration works better for those who use hardware calibrator displays at about 250:1 contrast. This type of display should visually and easily differentiate between all 256 steps when you open and display a 256 step target. If the shadow end is all quite dark and difficult to see, you can use contrast matching. The curve you end up with has the contrast matching embedded into it. It can be used in QTRgui or in OS X without CM to get its effects in the finished print. All that is in our documentation.
I hope everyone reading this can gain some valuable information.
Let us know how it goes!
Rachel
