Digital BW, The Print

Hi there
I'm new to this forum
I try to linearize with a Color Munki some of Paul Roark's excellent profiles  but I got the message after running the installer: Invalid linearize curve -- not constantly increasing.
I tried different set-ups  using the color munki B&W file from QTR and also the strip from
Keith Cooper. The print's dont look good. I see end the left side of the curve much more compressing then on the right side (QTR-Linearize-Data output file in TXT for the Mac.)
Does anyone have the same experience or can give me a solution?
Thanks
Mig

I'm new to this too (about 1 week into using QTR).  I've been working on generating curves for an R1800 with MIS UT inkset and a ColorMunki.  Here's what I've come up with for using the ColorMunki.

To get a "usable" linearization set of "L" values, the points need to be increasing in a fairly consistent manner.  Sometimes when using the Munki, a patch or two are not measured "correctly" in that the "L" values don't follow the rest of the curve.  This is especially noticable in the darkest patches, where the values may actually reverse (darker patches give higher "L" values.  I export the L*a*b values from the scanned palette and import them into Excel, where I can plot them ("L" vs. % black).  It becomes very apparent which patches fall off the curve.  I remove (delete) the offending point(s) then use a 6th order polynomial trendline to generate a smooth curve and use the coefficients to generate a smooth set of points.  These are then copied into the "L" values in the text file used to drop into the QTR-linearize droplet.  The resultant linearization values, when copied into the QTR ink descriptor, give a nice smooth curve.

"mig2012photo" <michielmegens@...> wrote:
>
>  I try to linearize with a Color Munki some of Paul Roark's excellent profiles  but I got the message after running the installer: Invalid linearize curve -- not constantly increasing. ...


Most often that error message is due to the profile hitting its dmax too soon -- before the 100% input point.  Or, the starting curve may be too compressed in the shadows.  QTR requires some minimum difference between the values.

The normal Adobe RGB and Gray Gamma 2.2 workspaces we use have compressed deep shadow areas.  I prefer my profiles to have some compression there before linearization because it gives the program more actual data as opposed to having it interpolate (guess at) the values.  There are some steep cross-overs going on down there that make getting smooth transitions difficult.  

First, I'd be sure the dmax is actually being reached at the 100% input point.  Print a calibration mode print or a 21-step with a straight line K 0 to 100 curve.  (I often use these, and they may be in the Zip files.)  

Second, if the ink limit or boost is set correctly, but the starting, pre-linearization compression is too much, try modifying the curves (if we're talking ICCs) or ink limits (QTR) that control the darkest dilute inks.

Good luck with the setup.  More information about the exact printer, inks, profiles, paper, and Lab L values might help. 

Paul
www.PaulRoark.com

Hi Paul thank you for your reply
I use Epson hot press natural on a Epson R1400 with eboni BO 
Qtr software 
Greetings
Mig

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul" <roark.paul@...> wrote:

>
> "mig2012photo" <michielmegens@> wrote:
> >
> >  I try to linearize with a Color Munki some of Paul Roark's excellent profiles  but I got the message after running the installer: Invalid linearize curve -- not constantly increasing. ...
> 
> 
> Most often that error message is due to the profile hitting its dmax too soon -- before the 100% input point.  Or, the starting curve may be too compressed in the shadows.  QTR requires some minimum difference between the values.
> 
> The normal Adobe RGB and Gray Gamma 2.2 workspaces we use have compressed deep shadow areas.  I prefer my profiles to have some compression there before linearization because it gives the program more actual data as opposed to having it interpolate (guess at) the values.  There are some steep cross-overs going on down there that make getting smooth transitions difficult.  
> 
> First, I'd be sure the dmax is actually being reached at the 100% input point.  Print a calibration mode print or a 21-step with a straight line K 0 to 100 curve.  (I often use these, and they may be in the Zip files.)  
> 
> Second, if the ink limit or boost is set correctly, but the starting, pre-linearization compression is too much, try modifying the curves (if we're talking ICCs) or ink limits (QTR) that control the darkest dilute inks.
> 
> Good luck with the setup.  More information about the exact printer, inks, profiles, paper, and Lab L values might help. 
> 
> Paul
> www.PaulRoark.com
>

On 12-05-31 4:57 AM, "wolverinemsu" <bchug@...> wrote:

> Sometimes when using the Munki, a
> patch or two are not measured "correctly" in that the "L" values don't follow
> the rest of the curve.  This is especially noticable in the darkest patches,
> where the values may actually reverse (darker patches give higher "L" values.
> I export the L*a*b values from the scanned palette and import them into Excel,
> where I can plot them ("L" vs. % black).  It becomes very apparent which
> patches fall off the curve.  I remove (delete) the offending point(s) then use
> a 6th order polynomial trendline to generate a smooth curve and use the
> coefficients to generate a smooth set of points.  These are then copied into
> the "L" values in the text file used to drop into the QTR-linearize droplet.
> The resultant linearization values, when copied into the QTR ink descriptor,
> give a nice smooth curve.

This looks interesting wolverinemsu.

A question. How do you know that those particular patches have been measured
incorrectly, as opposed to being a legitimate product of QTR, your ink set
and the paper you're using?

Terry.

What I have to watch with my DataColor unit is my lifting the meter too soon.  The way I know I've done this is that the color values (Lab A and B) will spike in one direction or the other -- way off the trend line.  I see this when I'm looking at the graphs in Excel.  What I do to correct the problem is simply go back and remeasure the patch correctly.  I simply write the new, correct values into the Excel boxes and save the file.

Paul
www.PaulRoark.com 

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Terry Ritz <t.ritz@...> wrote:

>
> On 12-05-31 4:57 AM, "wolverinemsu" <bchug@...> wrote:
> 
> > Sometimes when using the Munki, a
> > patch or two are not measured "correctly" in that the "L" values don't follow
> > the rest of the curve.  This is especially noticable in the darkest patches,
> > where the values may actually reverse (darker patches give higher "L" values.
> > I export the L*a*b values from the scanned palette and import them into Excel,
> > where I can plot them ("L" vs. % black).  It becomes very apparent which
> > patches fall off the curve.  I remove (delete) the offending point(s) then use
> > a 6th order polynomial trendline to generate a smooth curve and use the
> > coefficients to generate a smooth set of points.  These are then copied into
> > the "L" values in the text file used to drop into the QTR-linearize droplet.
> > The resultant linearization values, when copied into the QTR ink descriptor,
> > give a nice smooth curve.
> 
> This looks interesting wolverinemsu.
> 
> A question. How do you know that those particular patches have been measured
> incorrectly, as opposed to being a legitimate product of QTR, your ink set
> and the paper you're using?
> 
> Terry.
>

I have the same issue with my ColorMunki. I have to leave it in place until the light on the side goes off, or the patch slides into place in the measurement window (or both), or my measurement will be incorrect. 

Terry. 

On 2012-05-31, at 6:31 PM, "Paul" <roark.paul@...> wrote:

> What I have to watch with my DataColor unit is my lifting the meter too soon.  The way I know I've done this is that the color values (Lab A and B) will spike in one direction or the other -- way off the trend line.  I see this when I'm looking at the graphs in Excel.  What I do to correct the problem is simply go back and remeasure the patch correctly.  I simply write the new, correct values into the Excel boxes and save the file.
> 
> Paul
> www.PaulRoark.com 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Terry Ritz <t.ritz@...> wrote:
>> 
>> On 12-05-31 4:57 AM, "wolverinemsu" <bchug@...> wrote:
>> 
>>> Sometimes when using the Munki, a
>>> patch or two are not measured "correctly" in that the "L" values don't follow
>>> the rest of the curve.  This is especially noticable in the darkest patches,
>>> where the values may actually reverse (darker patches give higher "L" values.
>>> I export the L*a*b values from the scanned palette and import them into Excel,
>>> where I can plot them ("L" vs. % black).  It becomes very apparent which
>>> patches fall off the curve.  I remove (delete) the offending point(s) then use
>>> a 6th order polynomial trendline to generate a smooth curve and use the
>>> coefficients to generate a smooth set of points.  These are then copied into
>>> the "L" values in the text file used to drop into the QTR-linearize droplet.
>>> The resultant linearization values, when copied into the QTR ink descriptor,
>>> give a nice smooth curve.
>> 
>> This looks interesting wolverinemsu.
>> 
>> A question. How do you know that those particular patches have been measured
>> incorrectly, as opposed to being a legitimate product of QTR, your ink set
>> and the paper you're using?
>> 
>> Terry.
>> 
> 
> 
> 
> 
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On 06/01/2012 02:31 AM, Paul wrote:
> What I have to watch with my DataColor unit is my lifting the meter too
> soon. The way I know I've done this is that the color values (Lab A and
> B) will spike in one direction or the other -- way off the trend line. I
> see this when I'm looking at the graphs in Excel. What I do to correct
> the problem is simply go back and remeasure the patch correctly. I
> simply write the new, correct values into the Excel boxes and save the file.
>
> Paul
> www.PaulRoark.com


It is not that different with an X-Rite Eye 1 Pro. I count to three on 
each patch before lifting it. I also think that one should try to keep 
gloss paper patches as flat as possible under the spectrometer, the 
geometry of the spectrometer optics is not an ideal Ulbricht sphere but 
a practical compromise that works very nice with matte papers but less 
so with high gloss papers. Targets printed and dried fast with a hair 
dryer and then placed on more sheets of the same paper for measuring 
should be pressed firmly with the meter to get that patch flat.

There is another way to get the Lab b on a zigzag course. Measure a 
target with heavy bronzing and the 45/0 degree reflection optics in a 
spectrometer are affected by the bronzing layers. The measured color is 
not 1:1 to what the eye sees in color of the bronzing but that is 
understandable given the spectrocam's light source and sensor as another 
light + another observer. In practice one would not select a B&W 
paper/ink combination that creates that much bronzing but in color 
printing it may be less obvious and play a role when colors are off 
after profiling. Grey range in color prints for example. I will put some 
QTR linearisation plots on my site to show the difference between a 
target with and without bronzing.


-- 
Met vriendelijke groet, Ernst

Dinkla Grafische Techniek
Quad, pi\ufffdzografie, gicl\ufffde
www.pigment-print.com

I only remove those that are "way out of whack".  Since I use the 51-patch random test file, it becomes very clear when a point isn't even close to the model curve in Excel.  I use the strip mode in ColorMunki to read the patches, and sometimes I get an anomoly.

After reading some of the other posts in this thread, I have to admit that I'm sometimes not real careful about making sure the sheet is completely flat, that the Munki exactly follows the centerline of the patches, or doesn't tilt a little during the scan.  I've also found that the speed at which the Munki is moved over the patches can have an effect on the final output; too slow and it sometimes misses a patch completely.  I'm getting better at it, and will pay more attention to these things.

On 12-06-01 1:33 AM, "Ernst Dinkla" <e.dinkla@...> wrote:

> There is another way to get the Lab b on a zigzag course. Measure a
> target with heavy bronzing and the 45/0 degree reflection optics in a
> spectrometer are affected by the bronzing layers. The measured color is
> not 1:1 to what the eye sees in color of the bronzing but that is
> understandable given the spectrocam's light source and sensor as another
> light + another observer. In practice one would not select a B&W
> paper/ink combination that creates that much bronzing but in color
> printing it may be less obvious and play a role when colors are off
> after profiling. Grey range in color prints for example. I will put some
> QTR linearisation plots on my site to show the difference between a
> target with and without bronzing.

Not that's very interesting, and something well worth keeping in mind.

Would L* values suffer in this circumstance?

Terry.

On 06/01/2012 04:32 PM, Terry Ritz wrote:
> On 12-06-01 1:33 AM, "Ernst Dinkla" <e.dinkla@...
> <mailto:e.dinkla%40onsneteindhoven.nl>> wrote:
>
>  > There is another way to get the Lab b on a zigzag course. Measure a
>  > target with heavy bronzing and the 45/0 degree reflection optics in a
>  > spectrometer are affected by the bronzing layers. The measured color is
>  > not 1:1 to what the eye sees in color of the bronzing but that is
>  > understandable given the spectrocam's light source and sensor as another
>  > light + another observer. In practice one would not select a B&W
>  > paper/ink combination that creates that much bronzing but in color
>  > printing it may be less obvious and play a role when colors are off
>  > after profiling. Grey range in color prints for example. I will put some
>  > QTR linearisation plots on my site to show the difference between a
>  > target with and without bronzing.
>
> Not that's very interesting, and something well worth keeping in mind.
>
> Would L* values suffer in this circumstance?
>
> Terry.


Hardly I think. The 21 B&W step range is as good as the one that has no 
bronzing. Same paper, different inkset.


-- 
Met vriendelijke groet, Ernst

Dinkla Grafische Techniek
Quad, pi\ufffdzografie, gicl\ufffde
www.pigment-print.com