QTR-Quadtone RIP

For the Curve Creator tool:

When I look at the lineariztion tab for a paper (for example, Epson
Enhance Matte Neutral) I assume I'm seeing a numeric version of
something similar to Curves in Photoshop. 

I see steps in 5% increments, within a possible range from black
(100%) to whiten (0%). 

And I'm assuming that the numbers are indicating where a particular
tone will print lighter (such as where the first box is 96.86, instead
of what I think the 'default' should be which is 100), or where it
will print darker (such as the last box being 16.15 instead of 0). 

Am I interpreting these linearization numbers correctly? That they
tell the printer to print certain areas of the tonal range lighter or
darker (or the same)?  And that 100 is black or darkest, and 0 is
white or lightest? 

Thanks, David.

Hi David,

On 7/16/07, David <dkfreed@...> wrote:
> For the Curve Creator tool:
>
> When I look at the lineariztion tab for a paper (for example, Epson
> Enhance Matte Neutral) I assume I'm seeing a numeric version of
> something similar to Curves in Photoshop.

Yes, pretty similar idea.

>
> I see steps in 5% increments, within a possible range from black
> (100%) to whiten (0%).

It's actually white to black.  The numbers are luminosity values ie. Lab.
96.86 is paper white, 16.15 is dMax.   The numbers are all just readings
from a stepwedge.  You may also see some in density numbers going from
say 0.04 to 1.67 for instance.

What linearization does is apply a correction curve
based on these values.

Roy

>
> And I'm assuming that the numbers are indicating where a particular
> tone will print lighter (such as where the first box is 96.86, instead
> of what I think the 'default' should be which is 100), or where it
> will print darker (such as the last box being 16.15 instead of 0).
>
> Am I interpreting these linearization numbers correctly? That they
> tell the printer to print certain areas of the tonal range lighter or
> darker (or the same)?  And that 100 is black or darkest, and 0 is
> white or lightest?
>
> Thanks, David.
>

Thanks Roy. 

So if I understand you correctly, this curve is "lowering" or
lightening the black because the paper won't accept pure black? Is it
lightening the black or applying less ink?  

And when I applied the raw curve (UCmk-raw-neut.qidf) when I
printed--which has a blank linearization table--it printed, or tried
to print, full black to white? 

Best, David. 


--- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
>
> Hi David,

> 
> It's actually white to black.  The numbers are luminosity values ie.
Lab.

> 96.86 is paper white, 16.15 is dMax.   The numbers are all just readings
> from a stepwedge.  You may also see some in density numbers going from
> say 0.04 to 1.67 for instance.
> 
> What linearization does is apply a correction curve
> based on these values.
> 
> Roy

Pure black (dMax) stays the same.  The correction curve straightens all the
intermediate points.

Roy

On 7/16/07, David <dkfreed@...> wrote:
> Thanks Roy.
>
> So if I understand you correctly, this curve is "lowering" or
> lightening the black because the paper won't accept pure black? Is it
> lightening the black or applying less ink?
>
> And when I applied the raw curve (UCmk-raw-neut.qidf) when I
> printed--which has a blank linearization table--it printed, or tried
> to print, full black to white?
>
> Best, David.
>
>
> --- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
> >
> > Hi David,
>
> >
> > It's actually white to black.  The numbers are luminosity values ie.
> Lab.
> > 96.86 is paper white, 16.15 is dMax.   The numbers are all just readings
> > from a stepwedge.  You may also see some in density numbers going from
> > say 0.04 to 1.67 for instance.
> >
> > What linearization does is apply a correction curve
> > based on these values.
> >
> > Roy
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>

And one more question: Also, it looks like that Lab numbers don't
always equate to a 'mirror' of the grayscale percentages, is that
correct?  For example, it seems that 50% grayscale is 54 Lab and 85%
grayscale is 13 Lab. 

thanks again, David. 

--- In QuadtoneRIP@yahoogroups.com, "David" <dkfreed@...> wrote:

>
> Thanks Roy. 
> 
> So if I understand you correctly, this curve is "lowering" or
> lightening the black because the paper won't accept pure black? Is it
> lightening the black or applying less ink?  
> 
> And when I applied the raw curve (UCmk-raw-neut.qidf) when I
> printed--which has a blank linearization table--it printed, or tried
> to print, full black to white? 
> 
> Best, David.

That all depends on the embedded profile (or working space if you
don't have one).
The embedded profile tells you what the numbers "mean".  So in gray gamma 2.2
K=50 is L=54, in GG1.8 it would be L=60.   L values are absolute, K is
relative to
a profile.   There's a profile I made called GrayLab where the values
are linear,
so L+K=100.

The way to look at it is: K for grayscale, and R,G,B values for color are the
actual numbers in the file, an embedded profile tells what those numbers are
supposed to mean in luminosity (Lab).

Roy

On 7/16/07, David <dkfreed@...> wrote:
> And one more question: Also, it looks like that Lab numbers don't
> always equate to a 'mirror' of the grayscale percentages, is that
> correct?  For example, it seems that 50% grayscale is 54 Lab and 85%
> grayscale is 13 Lab.
>
> thanks again, David.
>
> --- In QuadtoneRIP@yahoogroups.com, "David" <dkfreed@...> wrote:
> >
> > Thanks Roy.
> >
> > So if I understand you correctly, this curve is "lowering" or
> > lightening the black because the paper won't accept pure black? Is it
> > lightening the black or applying less ink?
> >
> > And when I applied the raw curve (UCmk-raw-neut.qidf) when I
> > printed--which has a blank linearization table--it printed, or tried
> > to print, full black to white?
> >
> > Best, David.
>
>

Roy, not sure I understand below where you say "dMax stays the same" 
because in an earlier post you told me: 

"The numbers are luminosity values ie. Lab. 96.86 is paper white, 16.15 
is dMax" which indicates to me that you can change the black value and 
its not always "pure" black, 0.00. 

Again, I'm relating to a photoshop curve, where, for example, you 
changed bottom (black) end of curve to something like 86%, so darkest 
part of image would not be pure black (100%); and yes, rest of numbers 
would change intermediate points or values. 

Best, David. 
 

--- In QuadtoneRIP@...m, "Roy Harrington" <roy@...> wrote:
>
> Pure black (dMax) stays the same.  The correction curve straightens 
all the

> intermediate points.
> 
> Roy

Sorry for the confusion.  The correction curve maps K=100 in the file to dMax
on the paper.  Likewise K=0 maps to paper white.
The linearization basically stretches out the curve from 96-16 to 100-0.

Roy

On 7/17/07, David <dkfreed@...> wrote:
> Roy, not sure I understand below where you say "dMax stays the same"
> because in an earlier post you told me:
>
> "The numbers are luminosity values ie. Lab. 96.86 is paper white, 16.15
> is dMax" which indicates to me that you can change the black value and
> its not always "pure" black, 0.00.
>
> Again, I'm relating to a photoshop curve, where, for example, you
> changed bottom (black) end of curve to something like 86%, so darkest
> part of image would not be pure black (100%); and yes, rest of numbers
> would change intermediate points or values.
>
> Best, David.
>
>
> --- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
> >
> > Pure black (dMax) stays the same.  The correction curve straightens
> all the
> > intermediate points.
> >
> > Roy
>
>