QTR-Quadtone RIP

Like you I am new to QTR and it has take me some time to work through 
the documentation and to begin to make sense of it. It was only after 
scratching around for some time that I discovered how to specify the 
printer in the ink description file in order to be able to use 
Drop-Quad-Profile.app.

I am on a Mac, OS-X, using an Epson R2880 with Lyson's Photochrome R-28 
ink set with a CIS, and using Permajet's Gloss paper for testing. 
Initially my experience was similar to yours in that ABW gave a higher 
dMax than QTR; but with a revised ink description file with a higher K 
limit, I can now get a dMax of 2.37 with QTR, with excellent tonal 
distribution, vs. 2.29 with ABW. So I am minded to persevere with QTR.

I find that the Lyson inks are somewhat cooler then Epson's UC; so this 
requires some modification of the toner curves. Still experimenting.

QTR is a powerful and complex package which requires serious study to 
get to grips with it. It's a pity that the documentation is somewhat 
confusing for the beginner.

Tim


Jacob wrote:
> 
> 
> 
> I also would like to know what people think about it, but this group 
> looks very inactive.
> I'm new with QTR, here is my experience.
> 
> I print on Epson 7880 using Epson K3 inks with photo black ink from Mac 
> and PC. I've used QTR on Mac.
> 
> I've spend a week trying to figure out QTR and how to use it. I was a 
> computer programmer for 15 years supporting my photography habit, so I'm 
> not new to learning software. But this one was very tough because I'm 
> new to printing and documentation is in bits and pieces.
> In my software development days we used to spend 50% time documenting.
> 
> Next 2 days I've spent creating curves for Epson Luster paper. I created 
> ink curves - warm and cool- modifying ink files for Epson Matte paper 
> that came with QTR.
> I've got reversal at 90% in the cool curve. I searched through all forum 
> messages talking about this problem, tried to reduce ink limit up to 
> 45%, tried to change black-boost to 0%, changed gray_shadow and 
> gray_highlights values.
> Nothing worked, I still had reversal.
> 
> Then I've decided to try different paper, I've switched to Crane Museo 
> Silver Rag. This time I've got no reversal. But here I've got something 
> to think about.
> 
> Here is what I did. I've printed inkseraration file, figured ink limit 
> to be 70%, printed it again at 70%, figured relative density of gray 
> inks, created cool and warm curves modifying copies of ink files for 
> Epson Matte paper.
> 
> Then I've printed out the wedge (photoshop manages colors using 
> Gray_Photo_Paper.icc profile that came with QTR and using my new 
> curves), measured it.
> 
> Looked OK, no reversals, but curve looked kind of compressed on low 
> density where dark values are. Here are the Lab values:
> 5.51 6.24 7.43 11.60 16.77
> As you see the first numbers are pretty close, then they spread.
> 
> At this point I printed out the same wedge with ABW with no color 
> management on the same paper. And here I've got completely straight 
> line, here are the first Lab Values:
> 3.18 6.12 10.74 14.66 19.38
> 
> Now the question is: which line gives better print? One one hand second 
> (ABW) line should give more details in shadows. On other hand I've read 
> that human eye can see better details in highlights, so may be QTR 
> compressing the shadows where we can't see details anyway and gives us 
> better details in highlights?
> 
> I don't have answer to this.
> 
> I've proceeded with QTR doing linearization of curves, creating printer 
> profile, and also created printer profile for ABW using create_icc 
> application from QTR.
> 
> Next step: I printed out wedges using QTR with linearized curves and 
> printer profile and another one using ABW with printer profile created 
> with create_icc from QTR, measured them.
> 
> This time the line from QTR was completely linear, ABW line was 
> compressed at low density.
> 
> Here are the numbers for illustration:
> QTR 5.7 7.85 9.53 11.84 13.51 15.55 93.39 95.28 96.92
> ABW 3.22 3.45 4.19 6.28 8.84 10.90 93.32 94.99 96.98
> 
> AS you see D-max with ABW is higher, but I had dark-boost at 0 in QTR.
> 
> Then I printed out an image with dark tones with both QTR and ABW.
> To my surprise shadows were the same on both prints but light tones were 
> better with ABW, the print had more contrast in it. QTR print was kind 
> of dull.
> 
> It is quite possible that doing some adjustments in QTR I can get print 
> close to ABW quality, but I really doubt I can get a better one.
> 
> I've spent all this time after reading so many wonderful things about 
> QTR and I hoped to get better print quality.
> 
> May be it's all Epson's fault, they made a good driver and with it you 
> can change also ink limit, tone, curve shape.
> 
> It is interesting that completely straight line of ABW became compressed 
> in shadows after using printer profile created with qtr-create-icc. What 
> to make of it - is it by design, is it better this way?
> 
> Jacob
> http://www.photo3dart.com <http://www.photo3dart.com>