QTR-Quadtone RIP

I can't get linearised profiles to install for UT14 on Hahnemuhle Photo Rag Bright White.  I am getting the message "Invalid linearize curve -- not constantly increasing".   This is happening on both a warm and a cool profile.

The linearisation density values for both do constantly rise, however the paper white and 5% values are low and close, 0.02 and 0.04.  When the script runs in terminal, the line of numbers underneath the linearisation values has 100 twice at the end for both profiles.  The graphic curve representation ( lines of ****) also has lines (values) 244 and 255 near equal or equal.

Any ideas or advice?

Ross

If you are using QTR, be sure the C or M ink limit is set low enough that
it's maximum density at its ink limit is well below the dmax of the MK.
 You might also want to use the Black Boost for the last 10% of the MK ink
curve.  When you use the Boost, the second calibration print is done at the
K ink limit, not the Boost setting.

Paul
www.PaulRoark.com

On Sat, Feb 23, 2013 at 12:21 PM, rossfmj <ross.jarvis@...>wrote:

> **
>
>
> I can't get linearised profiles to install for UT14 on Hahnemuhle Photo
> Rag Bright White. I am getting the message "Invalid linearize curve -- not
> constantly increasing". This is happening on both a warm and a cool profile.
>
> The linearisation density values for both do constantly rise, however the
> paper white and 5% values are low and close, 0.02 and 0.04. When the script
> runs in terminal, the line of numbers underneath the linearisation values
> has 100 twice at the end for both profiles. The graphic curve
> representation ( lines of ****) also has lines (values) 244 and 255 near
> equal or equal.
>
> Any ideas or advice?
>
> Ross
>
>  
>


[Non-text portions of this message have been removed]

Paul

After the initial calibration and second calibration prints, I am getting a Dmax of 1.60 from the Black at 25% default ink limit., both C and M came in at 57% of that with Density of 1.25 (both are the same).  LC was 46% of C meaning 26% in the ink descriptor (at Density .80), if I've got this right and LM was 48% of M being 27% in the descriptor (Density .85).  Do the C and M percentages seem high?  

I'm really not sure how to set the Black Boost, when or why, or what numbers to use.

The cool descriptor including linearisation is;

# Ink positions:
# Black: Ebony black
# Magenta: Warm photo black
# Light Magenta: Dilute warm photo black
# Cyan: Cool photo black
# Light Cyan: Dilute cool photo black
# Yellow: Gloss optimizer ("GLOP")

GRAPH_CURVE=YES
N_OF_INKS=6
DEFAULT_INK_LIMIT=25
BOOST_K= 
LIMIT_K=
LIMIT_C=
LIMIT_M=
LIMIT_Y=
LIMIT_LC=
LIMIT_LM=

N_OF_GRAY_PARTS=3
GRAY_INK_1=K
GRAY_VAL_1=100
GRAY_INK_2=C
GRAY_VAL_2=57
GRAY_INK_3=LC
GRAY_VAL_3=26

GRAY_HIGHLIGHT=10
GRAY_SHADOW=10
GRAY_OVERLAP=
GRAY_GAMMA=1
GRAY_CURVE=

N_OF_TONER_PARTS=0
N_OF_TONER_2_PARTS=0

N_OF_UNUSED=3
UNUSED_INK_2=M
UNUSED_INK_3=LM
UNUSED_INK_4=Y

LINEARIZE="0.01 0.04 0.09 0.14 0.19 0.25 0.30 0.35 0.43 0.53 0.62 0.71 0.79 0.86 0.92 0.98 1.10 1.23 1.33 1.39 1.60"

thanks

Ross

--- In QuadtoneRIP@yahoogroups.com, Paul Roark <roark.paul@...> wrote:

>
> If you are using QTR, be sure the C or M ink limit is set low enough that
> it's maximum density at its ink limit is well below the dmax of the MK.
>  You might also want to use the Black Boost for the last 10% of the MK ink
> curve.  When you use the Boost, the second calibration print is done at the
> K ink limit, not the Boost setting.
> 
> Paul
> www.PaulRoark.com

rossfmj <ross.jarvis@...> wrote:

> **
>
>
> Paul
>
> After the initial calibration and second calibration prints, I am getting
> a Dmax of 1.60 from the Black at 25% default ink limit.,
>
That is low for H. Photo Rag.  Is that what your full Calibration Print at
100% showed as the darkest?  I just looked at an old 1400 H. Photo Rag QTR
profile that used Eboni MK, and the ink limit was 30 with a boost to 40.
 This produced a dmax of 1.71.


both C and M came in at 57% of that with Density of 1.25 (both are the
> same).
>
That sounds like it should be within range.  However, if you are getting
posterization or too low a slope in the gray ramp near the 100%, you might
want to lower the C and M ink limits.  A dark gray at 30 density is what I
see in the old (not UT14) profile I'm looking at.


In looking at your linearization numbers, it seems like the 95% to 100%
pre-linearization gap is more than I'd expect.  The 90 to 95% gap is too
small.  I wonder if your C curve was going flat there.  You might be able
to correct this by backing off on its ink limit.  Set the midtone ink
limits were the inks still have a good positive slope to them.



LC was 46% of C meaning 26% in the ink descriptor (at Density .80), if I've
> got this right and LM was 48% of M being 27% in the descriptor (Density
> .85).
>
It's OK only if it works!


> Do the C and M percentages seem high?
>

Not necessarily, but if the slopes are too flat by then, it could be a
problem.



> I'm really not sure how to set the Black Boost, when or why, or what
> numbers to use.
>

See the above comment.

Paul
www.PaulRoark.com




>
> The cool descriptor including linearisation is;
>
> # Ink positions:
> # Black: Ebony black
> # Magenta: Warm photo black
> # Light Magenta: Dilute warm photo black
> # Cyan: Cool photo black
> # Light Cyan: Dilute cool photo black
> # Yellow: Gloss optimizer ("GLOP")
>
> GRAPH_CURVE=YES
> N_OF_INKS=6
> DEFAULT_INK_LIMIT=25
> BOOST_K=
> LIMIT_K=
> LIMIT_C=
> LIMIT_M=
> LIMIT_Y=
> LIMIT_LC=
> LIMIT_LM=
>
> N_OF_GRAY_PARTS=3
> GRAY_INK_1=K
> GRAY_VAL_1=100
> GRAY_INK_2=C
> GRAY_VAL_2=57
> GRAY_INK_3=LC
> GRAY_VAL_3=26
>
> GRAY_HIGHLIGHT=10
> GRAY_SHADOW=10
> GRAY_OVERLAP=
> GRAY_GAMMA=1
> GRAY_CURVE=
>
> N_OF_TONER_PARTS=0
> N_OF_TONER_2_PARTS=0
>
> N_OF_UNUSED=3
> UNUSED_INK_2=M
> UNUSED_INK_3=LM
> UNUSED_INK_4=Y
>
> LINEARIZE="0.01 0.04 0.09 0.14 0.19 0.25 0.30 0.35 0.43 0.53 0.62 0.71
> 0.79 0.86 0.92 0.98 1.10 1.23 1.33 1.39 1.60"
>
> thanks
>
> Ross
>
> --- In QuadtoneRIP@yahoogroups.com, Paul Roark wrote:
> >
> > If you are using QTR, be sure the C or M ink limit is set low enough that
> > it's maximum density at its ink limit is well below the dmax of the MK.
> > You might also want to use the Black Boost for the last 10% of the MK ink
> > curve. When you use the Boost, the second calibration print is done at
> the
> > K ink limit, not the Boost setting.
> >
> > Paul
> > www.PaulRoark.com
>
>  
>


[Non-text portions of this message have been removed]

Paul, thanks again for your help.

I'm still getting not very far and am a bit concerned about using up paper at £1.30 (about$2) a shot
> > After the initial calibration and second calibration prints, I am getting
> > a Dmax of 1.60 from the Black at 25% default ink limit.,
> >
> That is low for H. Photo Rag.  Is that what your full Calibration Print at
> 100% showed as the darkest?  I just looked at an old 1400 H. Photo Rag QTR
> profile that used Eboni MK, and the ink limit was 30 with a boost to 40.
>  This produced a dmax of 1.71.

I can get density of MK up to 1.71 at 35%, however the rate of rise on the plot of calibration densities here is very low.  Plotting densities on Excel shows a steep rise from paper white (0.02) up to 25% MK giving 1.62 at this point the plot shows a rounded transition to near flat.  1.71 is the start of the flat part.

> both C and M came in at 57% of that with Density of 1.25 (both are the
> > same).
> >
> That sounds like it should be within range.  However, if you are getting
> posterization or too low a slope in the gray ramp near the 100%, you might
> want to lower the C and M ink limits.  A dark gray at 30 density is what I
> see in the old (not UT14) profile I'm looking at.

I'm not quite sure what you mean by posterisation.  On my 21 step prints for linearisation, the 100% step is very black and stands out from the 95%.  The 95% steps for cool and warm have a tint towards their respective "colours" and the 100% just seems black.  Is this posterisation?


> In looking at your linearization numbers, it seems like the 95% to 100%
> pre-linearization gap is more than I'd expect.  The 90 to 95% gap is too
> small.  I wonder if your C curve was going flat there.  You might be able
> to correct this by backing off on its ink limit.  Set the midtone ink
> limits were the inks still have a good positive slope to them.

I felt the jump to 100% seemed a bit big and out of step with the other increasing values.  I have brought the C and M limits down to 40% (of the MK value, now at 23% with boost to 28%) and plotting the density readings now shows a lift at the top end of the plot (when printing the new profiles on a 21 step wedge). However there is still a steep jump from the 95% step to the 100%.  (maybe I shouldn't have put the boost in at the same time as lowering the C & M values?). 

It seems a bit counter-intuitive that lowering the second grey value makes the top of the wedge darker, but I still have a lot to learn about what's going on. 

On a calibration print using the Inkseperation6.tiff, with the calibration set at 23%, there is no flat spot on C or M, they both keep rising in a smooth curve, not even levelling out.

> LC was 46% of C meaning 26% in the ink descriptor (at Density .80), if I've
> > got this right and LM was 48% of M being 27% in the descriptor (Density
> > .85).
> >
> It's OK only if it works!

Would I be correct in assuming, lowering the 3rd grey value would actually darken the lower end of the printed scale?

 regards

Ross