QTR-Quadtone RIP

You need to actually embed Adobe RGB or Gray Gamma 2.2 into the target to get the proper printed values.

Then linearize, and then your curve will print linear for any image embedded with a gray gamma 2.2 space (specifically Adobe 1998 and Grey Gamma 2.2)

best,
Walker


> On Dec 6, 2016, at 8:20 PM, nigglefish@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
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> I am using PrintTool and QTR on Mac OSX. I have been creating and linearising curves but I am a bit unsure of how to proceed to actual printing. I'm sure I can work it out through trial and error, but that won't help me understand the underlying color management concepts any better. So I thought I would describe what I have done and ask how I should proceed. (A few details have been simplified.)
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> 1) I created a .quad QTR curve using my own software and installed it.
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> 2) I created an 8-bit 18 patch grayscale target image in Gimp with each patch having a value 15 units higher than the last (0, 15, 30, 45, ..., 255). When I open this in PrintTool it reports the embedded profile as 'untagged'.
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> 3) I printed the target using PrintTool selecting 'No color management'. I used the QTR driver and selected my curve in the QTR print settings.
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> 4) I measured, adjusted, linearised and printed many times.
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> 5) I finally printed the target and measured linear lightness readings across the patches. That is, after measuring with a ColorMunki the difference between each adjacent patch in terms of L* readings was (just about) equal.
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> I'm happy to have gotten to this point, but I'm not sure if I have been headed to the right place or not. Maybe the desired readings for each patch should have been different? I don't know. I now have a photo I want to print. It reports an embedded profile of 'Adobe RGB (1998)' in PrintTool. I'm not sure what settings I should choose in terms of color management now to print that. I am assuming I should select 'No color management' again. But again I don't know.
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> So I have two questions:
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> 1) Given my target and printing options what lab readings should I be trying to get for each patch?
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> 2) Once I have achieved those readings what setting should I use to print a photo with an embedded profile.
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> Happy for any other information, background or guidance. Thanks in advance.
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