QTR-Quadtone RIP

Hi All,

After a long relationship with Imageprint, I find myself now looking for other solutions to make BW prints on my Epson 4000 with papers that are unprofiled for IP (and they are NOT getting one thin dime more from me!).  Having arrived at QTR, I've spent some time working through the process, and I have some questions...

Rather than simply following the curve/linearization steps with a new paper and calling it good, I've spent some time trying to duplicate the existing/known good profile installed with QTR for Moab Entrada Natural paper; that is, I've tried to build, from scratch, following the information that's out there for QTR, a paper curve/profile (what should I call this, exactly?) that is at least as good as the one that comes with QTR.  

I'm profiling with a scanner (Epson 3170), which of course is likely to be suboptimal, but it's what I have.  I do not currently have the resources for a true densitometer, or access to one that I can use (it's a VERY small town...).  Anyway, I've gotten to the point where if I had never found this test image:  http://www.northlight-images.co.uk/article_pages/black_and_white_test.html  I'd probably be pretty happy.  However, my profile produces banding in the circular gradient at the top of the page, where the QTR profile does not.  I've searched the group and have not found an answer to this, and am open to suggestions.  The remainder of the profile looks pretty good, and considering my low-budget measuring approach, I'm actually quite pleased.  Anyone have any suggestions for smoothing out the gradient through profiling?  Is this just a "benefit" of profiling with a scanner rather than the real deal?

My next question has to do with the gray curve shadow and highlight settings.  I've read several sources which suggest that these settings should be worked out before linearization; maybe I'm thinking too much (happens...) but if you adjust these settings before linearization, won't that adjustment then be neutralized by the linearizing process?  If I want to, say, pull down the highlights just a little, is this even the place to be doing it?

Thanks for all the help you've given me without knowing it; I've been working my way back through the archive and have picked up some serious pearls here and there.  I apologize if these issues have in fact been addressed previously, but I've had little luck with searching on these issues.  

I am somewhat unexpectedly really enjoying the measure/test/repeat process inherent in fine-tuning this approach—it's taken me right back to plotting gamma curves, etc in the film days!

Steve

Steve,
I have run into the same concerns that you have expressed. I had been  
using a scanner, an Epson Perfection 3200 Photo, to do my profiling. I  
have since acquired a PrintFix Pro densitometer which makes the measuring  
part of the process easier but has not alleviated the issues in profiling.  
I found the same issues in that I would go through the process of curve  
creation in QTR, linearize it and print the 21 step wedge and all would  
look good. In printing, however, I could see areas that did not look  
right. I, too, printed the same test image from NorthLight that you used  
and saw non-linear steps where there should have been none. Fiddling with  
the controls in QTR did not seem to help. I then imported the data from  
the .quad file that QTR generated into Excel to see what was going on. The  
individual ink curves were not very smooth. I generated a combined curve  
using the same parameters of relative ink densities that I used in QTR.  
Looking at that curve I could correlate bumps in the curve to where I was  
seeing steps in the printed test image. I am using Jon Cone's NK7 ink set  
in an Epson 2200. So, I next imported the data from one of Jon's supplied  
profiles such as the one for Moab Entrada Natural into Excel also. When  
comparing the two profiles, it was immediately obvious that Jon's  
individual ink curves are much smoother and had more overlap. The combined  
ink curve was also much smoother.

Now what I do is try to get a set of curves as close to matching the  
paper, either from QTR's curve creation process or based on one of Jon's  
profiles, and then manually modify the data in the .quad file to smooth it  
out to match the paper's properties. I do not yet have an automated way of  
doing this so it is a painstaking and time consuming process. Generally, I  
use densitometer measurements from the 21 step chart and visual  
inspections of the test image to determine what changes I need to make in  
the data. I make the changes where needed, smooth out the data points  
around the area and reprint the tests. After two or three iterations, I  
have a pretty good profile. I just need to figure out how to make this  
process easier. I know Jon charges $99 for this service to make a custom  
curve. Since I am retired and this is just a hobby not a money making  
pursuit, I have more time than money so I have to do these curves the hard  
way.

I have also peviously brought up these issues on this forum and not gotten  
any responses. If there is an easier way of doing this that I am missing I  
would be glad to be shown how to do it. Meanwhile I will continue down  
this path and will try to figure out a way to make the process more  
automated.

Steve T.


On Fri, 13 Mar 2009 06:20:53 -0700, alleycatnmilo <stuff@...>  
wrote:

> Hi All,
>
> After a long relationship with Imageprint, I find myself now looking for  
> other solutions to make BW prints on my Epson 4000 with papers that are  
> unprofiled for IP (and they are NOT getting one thin dime more from  
> me!).  Having arrived at QTR, I've spent some time working through the  
> process, and I have some questions...
>
> Rather than simply following the curve/linearization steps with a new  
> paper and calling it good, I've spent some time trying to duplicate the  
> existing/known good profile installed with QTR for Moab Entrada Natural  
> paper; that is, I've tried to build, from scratch, following the  
> information that's out there for QTR, a paper curve/profile (what should  
> I call this, exactly?) that is at least as good as the one that comes  
> with QTR.
>
> snip! . . .
> Steve
>
>
-- 
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Steve and Steve,
   I have been happily  making curves for my Epson PS1400 and the MIS UT-14 inkset.  Some of my curves definitely are "bumpy", but the output seemed OK.  But, after reading your posts, I downloaded the test file from Northlight and saw distinct rings in the radial patterns when I printed them.  As you describe, the discontinuities in the output correspond to the places that the curves look bumpy.  I played around a bit with smoothing the curves, and was able to improve the output significantly.

This seems to me to be a weakness in the QTR curve-generating programs, especially when the "linearization" routine.   My suspicion is that the problems are worst when the curves have to be modified extensively to linearize them.  It might be that the problem can be minimized by better optimizing the original curve, through judicious choice of parameters, so that the linearization routine doesn't have to distort the curves so much.


Has anyone asked Roy Harrington about this problem? 


David

I'm sure Roy monitors this list and I imagine, if he had anything to add,  
he would do so. I think what we are seeing is just inherent in the curve  
creation methods used in the program. I am very grateful that we have this  
program and also that Jon Cone supports it with his profiles. I am  
resigned to the fact that when stepping outside the supplied profiles, I  
am pretty much on my own. I was just hoping someone else would have  
already been down this path and would have developed some alternate  
methods to creating better custom curves.

Steve T.

On Tue, 17 Mar 2009 20:07:31 -0700, dpgoldenberg33  
<dpgoldenberg33@...> wrote:

> Steve and Steve,
>    I have been happily  making curves for my Epson PS1400 and the MIS  
> UT-14 inkset.  Some of my curves definitely are "bumpy", but the output  
> seemed OK.  But, after reading your posts, I downloaded the test file  
> from Northlight and saw distinct rings in the radial patterns when I  
> printed them.  As you describe, the discontinuities in the output  
> correspond to the places that the curves look bumpy.  I played around a  
> bit with smoothing the curves, and was able to improve the output  
> significantly.
>
> This seems to me to be a weakness in the QTR curve-generating programs,  
> especially when the "linearization" routine.   My suspicion is that the  
> problems are worst when the curves have to be modified extensively to  
> linearize them.  It might be that the problem can be minimized by better  
> optimizing the original curve, through judicious choice of parameters,  
> so that the linearization routine doesn't have to distort the curves so  
> much.
>
>
> Has anyone asked Roy Harrington about this problem?
>
>
> David
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>



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