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QTR,dMax and other stuff

QTR,dMax and other stuff

2005-01-30 by Fred Drury

For openers, let me echo the observations of others and salute this group 
for its contributions to the art, and its focus on helping everyone on the 
list improve their results.  It truly is a great forum and an incredible 
source of not only information but also inspiration.  Thanks to all of you 
... I find value every day's messages!

In a recent message to the list Steve Kale described his technique for 
countering what he describes as flatness in QTR prints.  In part he 
suggested:

If you want to see on screen the effect this weak dMax and QTR's
> linearization do the following.  Open a Gray Gamma 2.2 step wedge.  Add a
> Curves Layer (Layer->New Adjustment Layer->Curves->Enter).  Grab
> the bottom
> left anchor point and slide it up to (0,41) and grab the top right anchor
> and pull it down to (255,243).  Now look at how the input/outputs for the
> points in the middle have changed eg 128. For the most part, the image is
> lighter because the better part of the straight line has been shifted up
> (128 has gone to 142).  (Note that there is still nice visual separation
> between the steps on the screen which is QTR's linearization goal.)  When
> people say an image is flat it is largely, I believe, because all the
> mid-tones have been brightened.

He also suggested a method for countering the 'flatness' problem:

Add another curves layer. Lock (128,128).  Grab (63,63) and pull it down a
> little say to (63,43).  Grab (192,192) and shift it up a little say to
> (192,213).  This is what is meant by an s-curve - it is shaped like an s.
> You are adding a little punch to the highlights and darkening the
> shadows a
> little without shifting the mid.  You can view the effect of the second
> curve by itself by turning the visibility of the first off.  The effect on
> the image though will be the two curves combined.  The selection of points
> and how much to move them is really an artistic one but you have to judge
> the two together which is why I said keep the first curve visible.  Note
> that the first curve (a representation or simulation of what the RIP is
> doing) shifted the mid up point up and the second left it the same - ie
> still up.  So your mid grey will still be lighter than the original image
> without the curves.  You might choose to pull the mid darker in the second
> curve to counteract the effect of the RIP.  It's up to you.

I have done some experimenting with this method and thought I would both 
share the results with the group and seek suggestions for further 
experimentation. I first printed the image using QTR on EEM along with a 21 
step wedge file.  I'm printing on a 1280, using the MIS UT2 CIS and Roy's 
'neutral-2' profile, 1440 super, Better.  Measuring the step wedge with my 
i1-Photo instrument gave the following results 'L' results: 100%(black) -17, 
90%-26, 80%-35, 70%-42, 60%-51, 50%-57, 0% (paper)-97.  I then used a 
applied an 'S' curve of the type Steve described, reprinted on the same 
sheet of EEM along with another 21 step wedge file.  The contrast was 
clearly increased and the image had substantially increased 'punch'. 
Comparable results were: 100%(black) -17, 90%-22, 80%-28, 70%-36, 60%-47, 
50%-57, 0% (paper)-97.  The lowering of the 'L' values in the 60-90% range 
(and increased values in the 10-40% range) did produce a more attractive 
result.

A couple of questions for the group:
1)  The L=17 value corresponds to an RGB result of something like 46,46,46 
... ... is this the best (darkest) black I can expect to obtain using EEM? 
(Note: The 100%(black) result on Premium Luster (neutral-3 profile) was L=6)
2)  What alternate papers could I choose that would improve my blacks?, and 
how much improvement should I expect?
3)  Is there a way to convert my measurements to an equivalent dMax... 
alternatively, how can I measure dMax?
4)  Would working in Roy's recently posted Lab grayscale workspace permit 
moves towards improvement?

Some further questions for the group (I'm working with a PC system and so am 
anxiously awaiting the information on how those of us in PC land can go 
about making profiles):
1)  Does anyone on the forum have any idea when this information is likely 
to be available?
2)  I gather we PC'ers cannot currently do any soft proofing either?

With many thanks to this forum for past and future assistance,

Fred Drury
Markland Imaging

Re: QTR,dMax and other stuff

2005-01-30 by ldina

Fred,

> A couple of questions for the group:
> 1)  The L=17 value corresponds to an RGB result of something like 
46,46,46 ... is this the best (darkest) black I can expect to obtain 
using EEM? 

A measured L* value of 16 - 17 is generally about the best you can 
expect from EEM.  Different inks may give a little more or less Dmax, 
but that is generally the range.  Some people have tried various 
coatings to improve dmax, laminations, etc.  

> (Note: The 100%(black) result on Premium Luster (neutral-3 profile) 
was L=6)

Yep, glossy, satin and other coated papers will give you great Dmax, 
like you said, typically in the L* range of 4 to 10, again depending 
on paper, ink, etc.  Many people are beginning to use these papers 
and spray them to reduce bronzing, etc.  Mounting behind glass also 
helps.

> 2)  What alternate papers could I choose that would improve my 
blacks?, and how much improvement should I expect?

Kirkland Glossy (Costco) gives great dmax for a glossy paper, but is 
available only in 8.5X11 max to my knowledge.  Epson Prem Glossy, Ep 
Prem SemiMatte, and other will give pretty good dmax.

> 3)  Is there a way to convert my measurements to an equivalent 
dMax... alternatively, how can I measure dMax?

Bruce Lindbloom's site has a companding calculator which converts 
between L* and density.  www.brucelindbloom.com.

> 4)  Would working in Roy's recently posted Lab grayscale workspace 
permit moves towards improvement?

You get a better view of what you will see in print, but no, it is a 
paper/ink limitation.

Lou

Re: [Digital BW] QTR,dMax and other stuff

2005-01-30 by Steve Kale

Fred

Take a look at Roy's latest stuff.  He has found a way to use the Perceptual
Intent and icc profiles to manage the required compression of tonal range.
Quite cool. The way to think about it is an automatic way of dealing with
the issue I was describing and one that draws on all the skill/technology
already available to the colour-managed world.  At the end of the day, while
your image file can have a range in L from 0-100 you will always be
constrained by the print/ink media.  Roughly, a range of 96/97 to 16/17 for
matte paper and down to 5-9 for RC paper.  Until we get better inks this is
what we have to deal with.  The use of glop has greatly improved the use of
RC paper and opened up potential dMax from around 1.65 to 2.2-4.  Less tonal
compression required as a result.  Working with Roy's Lab space doesn't
expand the available range but does mean that it is easier to deal with the
tonal compression in a more rigorous fashion. Take a look at the note on his
website.  It also means soft-proofing is much easier.  In essence, he uses
Perceptual Intent to do the job of the s-curves.

Steve 
Show quoted textHide quoted text
> From: Fred Drury <fotofred2@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Sun, 30 Jan 2005 11:57:16 -0600
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] QTR,dMax and other stuff
> 
> 
> For openers, let me echo the observations of others and salute this group
> for its contributions to the art, and its focus on helping everyone on the
> list improve their results.  It truly is a great forum and an incredible
> source of not only information but also inspiration.  Thanks to all of you
> ... I find value every day's messages!
> 
> In a recent message to the list Steve Kale described his technique for
> countering what he describes as flatness in QTR prints.  In part he
> suggested:
> 
> If you want to see on screen the effect this weak dMax and QTR's
>> linearization do the following.  Open a Gray Gamma 2.2 step wedge.  Add a
>> Curves Layer (Layer->New Adjustment Layer->Curves->Enter).  Grab
>> the bottom
>> left anchor point and slide it up to (0,41) and grab the top right anchor
>> and pull it down to (255,243).  Now look at how the input/outputs for the
>> points in the middle have changed eg 128. For the most part, the image is
>> lighter because the better part of the straight line has been shifted up
>> (128 has gone to 142).  (Note that there is still nice visual separation
>> between the steps on the screen which is QTR's linearization goal.)  When
>> people say an image is flat it is largely, I believe, because all the
>> mid-tones have been brightened.
> 
> He also suggested a method for countering the 'flatness' problem:
> 
> Add another curves layer. Lock (128,128).  Grab (63,63) and pull it down a
>> little say to (63,43).  Grab (192,192) and shift it up a little say to
>> (192,213).  This is what is meant by an s-curve - it is shaped like an s.
>> You are adding a little punch to the highlights and darkening the
>> shadows a
>> little without shifting the mid.  You can view the effect of the second
>> curve by itself by turning the visibility of the first off.  The effect on
>> the image though will be the two curves combined.  The selection of points
>> and how much to move them is really an artistic one but you have to judge
>> the two together which is why I said keep the first curve visible.  Note
>> that the first curve (a representation or simulation of what the RIP is
>> doing) shifted the mid up point up and the second left it the same - ie
>> still up.  So your mid grey will still be lighter than the original image
>> without the curves.  You might choose to pull the mid darker in the second
>> curve to counteract the effect of the RIP.  It's up to you.
> 
> I have done some experimenting with this method and thought I would both
> share the results with the group and seek suggestions for further
> experimentation. I first printed the image using QTR on EEM along with a 21
> step wedge file.  I'm printing on a 1280, using the MIS UT2 CIS and Roy's
> 'neutral-2' profile, 1440 super, Better.  Measuring the step wedge with my
> i1-Photo instrument gave the following results 'L' results: 100%(black) -17,
> 90%-26, 80%-35, 70%-42, 60%-51, 50%-57, 0% (paper)-97.  I then used a
> applied an 'S' curve of the type Steve described, reprinted on the same
> sheet of EEM along with another 21 step wedge file.  The contrast was
> clearly increased and the image had substantially increased 'punch'.
> Comparable results were: 100%(black) -17, 90%-22, 80%-28, 70%-36, 60%-47,
> 50%-57, 0% (paper)-97.  The lowering of the 'L' values in the 60-90% range
> (and increased values in the 10-40% range) did produce a more attractive
> result.
> 
> A couple of questions for the group:
> 1)  The L=17 value corresponds to an RGB result of something like 46,46,46
> ... ... is this the best (darkest) black I can expect to obtain using EEM?
> (Note: The 100%(black) result on Premium Luster (neutral-3 profile) was L=6)
> 2)  What alternate papers could I choose that would improve my blacks?, and
> how much improvement should I expect?
> 3)  Is there a way to convert my measurements to an equivalent dMax...
> alternatively, how can I measure dMax?
> 4)  Would working in Roy's recently posted Lab grayscale workspace permit
> moves towards improvement?
> 
> Some further questions for the group (I'm working with a PC system and so am
> anxiously awaiting the information on how those of us in PC land can go
> about making profiles):
> 1)  Does anyone on the forum have any idea when this information is likely
> to be available?
> 2)  I gather we PC'ers cannot currently do any soft proofing either?
> 
> With many thanks to this forum for past and future assistance,
> 
> Fred Drury
> Markland Imaging 
> 
> 
> 
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