QTR-Quadtone RIP

Many thanks for the reply, Steve.

<Copy the data from the appropriate .quad file into Excel>

I opened a .quad file in Excel and graphed a couple of the ink positions, but need more details on how to effectively work with this data using this technique. 

An easier (for me) alternative has been to create a Photoshop adjustment curve and lighten / darken the points that need it. This works, but I was hoping to do everything in QTR. But this seems impossible since I'll usually be blending curves, which necessitates some post-QTR tweaking. I've found that two very linear curves (i.e. my warm and cool curves) don't blend in a perfectly linear way.

< Eventually, I stopped printing circular gradients and have been much more content since then.  I don't think that I have seen anything in a real print that reflects this artifact.>

I acknowledge this may be the case, but I know I'll be more content if I obsess a while longer on creating the most linear curves I can!

Mark 
 

--- In QuadtoneRIP@yahoogroups.com, "Steve and Ann Taylor" <taylorfamily3688@...> wrote:
>
> Since nobody has jumped in on this, I'll give a quick description of what  
> I have done. Mine is a strictly manual operation. Copy the data from the  
> appropriate .quad file into Excel or OpenOffice Calc and separate the  
> individual ink curves. You can create a composite curve by applying your  
> relative ink density values to each ink curve and then combining the  
> resulting values. Graph the ink curves and locate the areas where the  
> "bumps" are located. Look for any suspicious inflections in the underlying  
> ink curves at those points and manually change the values to straighten  
> them out. Then copy the resulting data values back into the .quad file.  
> Then do a new test print and check to see if the changes have helped.
> 
> Once you have manually edited the .quad data, you can no longer use the  
> QTR program to make any changes or new linearizations.
> 
> I realize my quick description may not be adequate without a much more  
> detailed explanation. If you need help, please contact me off list.
> 
> As a previous poster said:
> 
> "I have also found lots of rings with the Northlight Images circular  
> gradients, using my profiles for the UT14 inkset.  I think that the  
> circular gradients are especially sensitive to small bumps in the curve,  
> but don't reflect the overall linearity much.
> 
> I spent some time trying to tweak the curves to make the rings go away.   
> Eventually, I stopped printing circular gradients and have been much more  
> content since then.  I don't think that I have seen anything in a real  
> print that reflects this artifact.
> 
> David"
> 
> I also have fussed over rings in the Northlight Images circular gradients  
> pattern. For the most part, small "bumps" might not be visible in most  
> images, but if you have large areas of a smooth gradient, such as a sky,  
> they may show up.
> 
> Steve
> 
> 
>       On Wed, 08 Feb 2012 06:51:49 -0800, mccarvill <mccarvill@...>  
> wrote:
> 
> > Any recommendations on how to fix small bumps that persist after  
> > linearization? By `small bump' I mean a 2% or so deviation from the  
> > ideal linearization for any given point on the line. For example, I did  
> > a warm Eboni-4-Plus  curve for Alise Natural on my Epson 1400, and the  
> > curve is perfectly linear (i.e. the points deviate less than 1%) except  
> > at the 50% and 80% patches, which are 1.5% and 2.5% lighter than ideal,  
> > respectively.
> >
> > I grant that these two small bumps might not be noticeable in prints,  
> > but I'd like to get a perfect curve if I can.
> >
> > Thanks,
> >
> > Mark
> >
> >
> >
> >
> > ------------------------------------
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> 
> 
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