QTR-Quadtone RIP

Yes, Howard, I was using the Ordered dither algorithm.  But I'll keep
that in mind as a variable to watch out for in future.

--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:
>
> Mike, are you using the Ordered dither algorithm? If not try switching 
> to that.
> 
> Howard
> 
> Mike Dawson wrote:
> > jr,
> > 
> > Thanks for your detailed post.  No, I am not getting banding in the 
> > initial 21-step wedges for the individual inks during calibration 
> > mode.  I am getting banding on the 21step.tif file that is printed 
> > out after you take QTRgui out of calibration mode.  This is the step 
> > wedge that I need to measure in order to linearize the curve.
> > 
> > This is also not the type of banding you see with a clogged nozzle.  
> > I check my nozzles before and after each calibration print to verify 
> > that I didn't have a clog during the calibration print.  The banding 
> > I'm talking about is not the fine line banding that is typical with a 
> > missing nozzle.  These are gradient bands (if that description makes 
> > any sense) that seem like they would be due to improper overlap 
> > (partitioning) of the 6 inks upon printout.  These gradient bands are 
> > obvious in the smooth gradient that runs across the top of the step 
> > wedge.  The bands extend down into the 5% blocks and it seems would 
> > have an impact on the measuring of the 5% blocks for linearization.
> > 
> > But I will read through your description and cross check against my 
> > process.
> > 
> > Mike
> > 
> > --- In QuadtoneRIP@yahoogroups.com, "Jeff Randall" <jrandall@> 
> > wrote:
> >>
> >> Mike:  
> >> 
> >> I assume you see the banding in the calibration print stepwedges. 
> > Do 
> >> you see banding in just one ink's wedge or in all wedges? Banding 
> > is 
> >> usually caused either by clogs, dirty underside of printhead, 
> >> airleaks, or incomplete purging of old inks associated with the 
> >> particular ink step-wedge.  Banding in all wedges is often a 
> >> stepping motor/paper advance problem.  
> >> 
> >> I have found that I get better results *generally* following Tom 
> >> Moore's procedure than Paul Roark's. YMMV! [Desclaimer:  The last 
> >> inkset I profiled was Paul Roark's K4+Ccm--I have no experience 
> > with 
> >> Cone inks.]  If I had your first calibration print at 100%, I'd set 
> >> the K default limit to something between 50% and 80%, maybe 65 or 
> >> 75%--I'd have to see the results.   Then I'd print out the second 
> >> calibration print at what ever % I decided on to make the second 
> >> calibration print and calculate the relative ink densities to K at 
> >> that % leaving the limits of the other grays blank and set Black 
> >> Boost to something like 85% or 90%.  I'd also set the Gray Curves 
> >> tab values to something like 6,6,_,1.  This will darken the 
> >> resulting stepwedge below that created by the default values, but 
> > as 
> >> Paul says it helps smooth the transition between the 95 and 100% 
> >> steps and it linearizes well for me.  This would become my base 
> >> profile.  I'd print out a 21-step wedge and use my 
> >> densitometer/colorimeter to measure the density or Lab L and plot 
> >> against the step number or % value. The result should be a smooth 
> >> curve below the straight line connecting the 0 and 100 readings 
> > (see 
> >> Paul Roark's figure).  I then would adjust ink limits as needed to 
> >> get a smooth curve (for me it usually is the darkest gray I need to 
> >> tweak the most).
> >> 
> >> Hope this helps.  There are no hard and fast rules.  Creating 
> >> profiles from scratch still has a strong component of art ...
> >> 
> >> jr
> >> 
> >> 
> >> 
> >> 
> >> --- In QuadtoneRIP@yahoogroups.com, "Mike Dawson" <dawsonm@> 
> >> wrote:
> >> >
> >> > 
> >> > Can anyone give me some common causes of banding in the step 
> >> wedge?  
> >> 
> >> 
> >> > With the 1280/K6/Epson VFA combination I found that the ink limit 
> >> for 
> >> > the Black ink was at 80%.  The density shoulder actually begins 
> >> > occuring at about 50% with a density of 1.62.  It hits 1.69 at 
> > 80% 
> >> > and holds that value up until 100%.
> >> > 
> >> > I then printed out the ink separation test using an ink limit of 
> >> > 85%.  I then determined the densities (compared to Black) of all 
> >> the 
> >> > other inks from the 100% squares.
> >> > 
> >> > I also measured all ink patches from the first ink separation 
> >> test.  
> >> > Based on advice from Paul Roarke I used the ink limits from these 
> >> > measurements to plug into the curve creation windows.  I found 
> >> that 
> >> > ALL of the inks (except for Black) had no plateau and were 
> >> increasing 
> >> > in density all the way up to 100%.  So I plugged in 100% ink 
> > limit 
> >> > for all the inks, except for Black which has the default of 80%.  
> >> > Black Boost was left blank.
> >>
> > 
> > 
> > 
> > 
> >  
> > Yahoo! Groups Links
> > 
> > 
> > 
> > 
> 
> -- 
> Howard Shaw
> glassman@...
> www.howardshaw.org
>