QTR-Quadtone RIP

I have started the process of creating a profile for the Cone K6 inks 
on Epson Velvet Fine Art using an Epson 1280 printer.  I am getting a 
bit stumped at the point where you print out the 21-step wedge in 
order to linearize the curve.  The issue is that the step wedge has 
fairly obvious banding at densities above 65%.  This seems like it 
would be an issue when trying to take accurate density readings 
(using my ColorVision Spectro 1005).

Can anyone give me some common causes of banding in the step wedge?  
I'm assuming it is due to poor data plugged in from ink separation 
test prints.  But I'm hoping others can clue me in to what 
specifically may be the cause of the banding.

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.

Any help here?

Mike

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.

this may be a clog. 

i've just encountered this on my 21-step-random print. the banding (or more like pin 
strips) appear in the 30, 45, 20, 35, 50, 25, and 40 patches. i ran the head cleaning cycle 
and it took care of it. perhaps it's the same with yours.

--- In QuadtoneRIP@yahoogroups.com, "Mike Dawson" <dawsonm@...> wrote:

>
> I have started the process of creating a profile for the Cone K6 inks 
> on Epson Velvet Fine Art using an Epson 1280 printer.  I am getting a 
> bit stumped at the point where you print out the 21-step wedge in 
> order to linearize the curve.  The issue is that the step wedge has 
> fairly obvious banding at densities above 65%.  This seems like it 
> would be an issue when trying to take accurate density readings 
> (using my ColorVision Spectro 1005).
> 
> Can anyone give me some common causes of banding in the step wedge?  
> I'm assuming it is due to poor data plugged in from ink separation 
> test prints.  But I'm hoping others can clue me in to what 
> specifically may be the cause of the banding.
> 
> 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.
> 
> Any help here?
> 
> Mike
>

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.
>

Agreed, the smooth ramp gradient nonlinearities you are describing are 
associated with poor ink density partitioning.  It is not QTR's fault 
(at least at this stage). Try updating your relative ink densities 
following more Tom Cooper than Paul Roark work flows.  The resulting 
plot of the measured nonlinear step L values verse step number or step 
% should look like the Paul Roark figure (a smooth curve below the 
line connecting 0 and 100% L -- indicating darker steps than the final 
linearized steps).  Note:  These are the values you plug back into 
your non-linear QTR profile to create a final linear profile.

Good luck. 

--- In QuadtoneRIP@yahoogroups.com, "Mike Dawson" <dawsonm@...> wrote:

> 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. 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.

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

Mike

Another cause I have experienced for banding is over-inking. You could try
reducing the ink limits in your curve to see if the banding is reduced.

Another clue to over-inking can be found by looking at your step wedge
through a loupe (or a detailed scan). The edges of black areas (such as the
100% wedge or black text) will show excessive bleeding and/or spatter into
adjacent lighter areas.

Tom Moore

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
>

Thanks Tom.  A good suggestion.  I'll take a look.

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <r.t.moore@...> wrote:
>
> Mike
> 
> Another cause I have experienced for banding is over-inking. You
could try
> reducing the ink limits in your curve to see if the banding is reduced.
> 
> Another clue to over-inking can be found by looking at your step wedge
> through a loupe (or a detailed scan). The edges of black areas (such
as the
> 100% wedge or black text) will show excessive bleeding and/or
spatter into

> adjacent lighter areas.
> 
> Tom Moore
>