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QTR-Quadtone RIP

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QTR-Lab profiles vs none

QTR-Lab profiles vs none

2007-02-01 by Piet Weber

Hi,

You have been helping me with my last problem (post 3689), and you have resolved it! 
Now, if someone could help me clearing this issue, I will be a happy QTR user. I cannot 
seem to find this issue in older posts, but I am sure this is not a new subject.

After I did linearize my profiles, I was able to print in nice B/W tones, using a 2100 and 
Piezography K7 ink. (To linearize, I opened the 21-gray step file, without color profile, and 
also print this file without color management) But to make it more complicated QTR 
profiles were designed...

(1) The way I used to print is as follows. The greytone picture is converted to the 'gamma 
2.2' profile. Now, print with preview, select 'no color management', hit print, and select the 
correct qtr profile in the Epson dialoge.

(2) Now, Roy gave us QTR profiles. Okay, I convert my picture from 'gamma 2.2' to 'QTR 
RGB Lab'. In the print dialoge I select 'QTR RGB matte' and perceptual rendering. In the 
Epson dialoge, I select the corrct QTR profile.

What is the difference between the to outputs (1) and (2)? The first (1) gives me almost 
correct midtone values (compared to the 'ideal density diagram'). Printing with the new 
option (2) gives me darker midtones. The 50% gray compares to the 55% gray without 
using the QTR profiles. Reading the instructions in the program software, I read that this is 
what the QTR RGB matte does. It is ment to print darker midtones! But why? After all the 
hassle to create a smooth curve (excellent results!), I now have to use a profile (QTR Lab) 
that adjusts it!

Do I miss something? If I want to keep using the smooth paper profile I made myself, 
should I then not use the QTR profiles? In what specific situation should I use these 
profiles? And what is the difference between the matte and photo profle in the print 
dialoge? The instruction are not very clear to me!

Anyone willing to explain me a bit about this matter? Or direct me to a posted message 
that I have missed?

Cheers, Piet

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