QTR-Quadtone RIP

Hi.  

I'm really confused about a particular point (well, in fact I'm 
confused about a load of things relating to QTR, profiles, Dmax, L*, 
etc etc etc - but this is the first question on my list!!!).  
Grateful for any help!

I have been playing around with QTR on Windows and my Epson 2200 for 
a few weeks.  I use CS2 and ConvertToB&WPro V3 for image 
manipulation (usually limited to dodging & burning), Qimage (print 
to file) for final print interpolation and sharpening and 
the "canned" QTR EEH curves for final printing on EEH (usually 75% 
cool 25% warm works well for me).  

The print output file produced by Qimage does not have an embedded 
profile (when I open the file from CS2 it asks me if I want to 
assign a profile).  What should I do at this point – should I assign 
a profile before printing or not?  And if I do, which profile should 
I assign – Adobe RGB, Dot Gain 20%, or one of the QTR profiles?  Or 
does this not matter one iota to QTR?

I've tried to find the answer in the manuals and this forum but I'm 
hopelessly uneducated in this whole subject and totally overwhelmed 
by the jargon!

Thanks for any advice!

John Wood

John

I'm not sure why you are opening the Qimage output file in Photoshop -
perhaps it's just curiosity. In any event, I don't think QTR looks at any
embedded ICC profile, if present. 

Here's how I understand these matters.

If you "Assign" a profile to an image, it would not affect how QTR would
print that image, although it would likely change the way you see the image
on your monitor. That is because you are not changing the RGB values of each
pixel (or gray value is grayscale) but you may be changing the meaning of
these values. 

However, if you "Convert" an image to an ICC profile, then its appearance
would not change on your monitor, but it would likely change how the printed
image appears. That is because the RGB values for each pixel would likely be
changed but the newly associated ICC profile would preserve its appearance
on the monitor. However, since QTR does not look at ICC profiles, the
modified RGB values would change the way the image is printed.

Here's how I use this info in my workflow:

1.	when working up an image in PS, I convert it to Gray-LAB (for
grayscale) or RGB-LAB (for an RGB image) early in the process. I don't think
it matters at this point whether I use Assign or Convert as long as the
image has one of the LAB (from the QuadToneRIP\Icc folder) profiles
assigned. You can convert/assign to the LAB profile at any time. I do it
early in the process because doing so can have significant effect on the
image histogram, and I think it's better to do it before I adjust the tonal
range pf the image, which I do early in the manipulation process.

2.	If the curves I intend to use for printing have an associated ICC
profile, I use this profile with the PS soft proof feature to preview how my
image's tonal range will be mapped onto the tonal range available for the
paper/ink combination for those curves. Otherwise I could use the generic
profiles for matte paper (Gray-Matte or RGB-Matte) or photo paper
(Gray-Photo or RGB-Photo).

3. Currently, I print from PS by saving a flattened tiff file once I am
happy with the image. I'm not sure of the process with Qimage. I currently
have the demo to see how beneficial it might be.

Tom Moore

> -----Original Message-----
> From: QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com] On
> Behalf Of John Wood
> Sent: Sunday, October 30, 2005 2:10 PM
> To: QuadtoneRIP@yahoogroups.com
> Subject: [QuadtoneRIP] Confusion regarding Profiles and QTR
> 
> Hi.
> 
> I'm really confused about a particular point (well, in fact I'm
> confused about a load of things relating to QTR, profiles, Dmax, L*,
> etc etc etc - but this is the first question on my list!!!).
> Grateful for any help!
> 
> I have been playing around with QTR on Windows and my Epson 2200 for
> a few weeks.  I use CS2 and ConvertToB&WPro V3 for image
> manipulation (usually limited to dodging & burning), Qimage (print
> to file) for final print interpolation and sharpening and
> the "canned" QTR EEH curves for final printing on EEH (usually 75%
> cool 25% warm works well for me).
> 
> The print output file produced by Qimage does not have an embedded
> profile (when I open the file from CS2 it asks me if I want to
> assign a profile).  What should I do at this point - should I assign
> a profile before printing or not?  And if I do, which profile should
> I assign - Adobe RGB, Dot Gain 20%, or one of the QTR profiles?  Or
> does this not matter one iota to QTR?
> 
> I've tried to find the answer in the manuals and this forum but I'm
> hopelessly uneducated in this whole subject and totally overwhelmed
> by the jargon!
> 
> Thanks for any advice!
> 
> John Wood

Thanks to both Toms (Moore and Husband).  Apart from the fact that I 
understand what is going on slightly more, I have use advice from 
both to fine tune my workflow.  I now convert to RGB-LAB in CS2 when 
working on the original image (just after conversion to B&W) and 
soft proof using QTR-RGB Matte.  My final output file in Qimage is 
saved with profile QTR-RGB Matte and the final print matches much 
closer what I see on screen than previously! 

Another quesion this time re soft proofing.  Should one normally use 
the "Simulate Black Ink" option?  In my case I find the final print 
output is somewhere between the two (i.e. simulate on or simulate 
off) in terms of density of blacks.

Thanks again,

John

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <r.t.moore@r...> 
wrote:
>
> John
> 
> I'm not sure why you are opening the Qimage output file in 
Photoshop -
> perhaps it's just curiosity. In any event, I don't think QTR looks 
at any
> embedded ICC profile, if present. 
> 
> Here's how I understand these matters.
> 
> If you "Assign" a profile to an image, it would not affect how QTR 
would
> print that image, although it would likely change the way you see 
the image
> on your monitor. That is because you are not changing the RGB 
values of each
> pixel (or gray value is grayscale) but you may be changing the 
meaning of
> these values. 
> 
> However, if you "Convert" an image to an ICC profile, then its 
appearance
> would not change on your monitor, but it would likely change how 
the printed
> image appears. That is because the RGB values for each pixel would 
likely be
> changed but the newly associated ICC profile would preserve its 
appearance
> on the monitor. However, since QTR does not look at ICC profiles, 
the
> modified RGB values would change the way the image is printed.
> 
> Here's how I use this info in my workflow:
> 
> 1.	when working up an image in PS, I convert it to Gray-LAB (for
> grayscale) or RGB-LAB (for an RGB image) early in the process. I 
don't think
> it matters at this point whether I use Assign or Convert as long 
as the
> image has one of the LAB (from the QuadToneRIP\Icc folder) profiles
> assigned. You can convert/assign to the LAB profile at any time. I 
do it
> early in the process because doing so can have significant effect 
on the
> image histogram, and I think it's better to do it before I adjust 
the tonal
> range pf the image, which I do early in the manipulation process.
> 
> 2.	If the curves I intend to use for printing have an 
associated ICC
> profile, I use this profile with the PS soft proof feature to 
preview how my
> image's tonal range will be mapped onto the tonal range available 
for the
> paper/ink combination for those curves. Otherwise I could use the 
generic
> profiles for matte paper (Gray-Matte or RGB-Matte) or photo paper
> (Gray-Photo or RGB-Photo).
> 
> 3. Currently, I print from PS by saving a flattened tiff file once 
I am
> happy with the image. I'm not sure of the process with Qimage. I 
currently
> have the demo to see how beneficial it might be.
> 
> Tom Moore
> 
> > -----Original Message-----
> > From: QuadtoneRIP@yahoogroups.com 
[mailto:QuadtoneRIP@yahoogroups.com] On
> > Behalf Of John Wood
> > Sent: Sunday, October 30, 2005 2:10 PM
> > To: QuadtoneRIP@yahoogroups.com
> > Subject: [QuadtoneRIP] Confusion regarding Profiles and QTR
> > 
> > Hi.
> > 
> > I'm really confused about a particular point (well, in fact I'm
> > confused about a load of things relating to QTR, profiles, Dmax, 
L*,
> > etc etc etc - but this is the first question on my list!!!).
> > Grateful for any help!
> > 
> > I have been playing around with QTR on Windows and my Epson 2200 
for
> > a few weeks.  I use CS2 and ConvertToB&WPro V3 for image
> > manipulation (usually limited to dodging & burning), Qimage 
(print
> > to file) for final print interpolation and sharpening and
> > the "canned" QTR EEH curves for final printing on EEH (usually 
75%
> > cool 25% warm works well for me).
> > 
> > The print output file produced by Qimage does not have an 
embedded
> > profile (when I open the file from CS2 it asks me if I want to
> > assign a profile).  What should I do at this point - should I 
assign
> > a profile before printing or not?  And if I do, which profile 
should
> > I assign - Adobe RGB, Dot Gain 20%, or one of the QTR profiles?  
Or
> > does this not matter one iota to QTR?
> > 
> > I've tried to find the answer in the manuals and this forum but 
I'm
> > hopelessly uneducated in this whole subject and totally 
overwhelmed

> > by the jargon!
> > 
> > Thanks for any advice!
> > 
> > John Wood
>

With QTR-RGB Matte, you're soft proofing with a "canned" icc profile that
won't precisely match your paper. That means that you will have to pick
options (simulate paper white and/or ink black) that give you the best
result.

When, using a profile created specifically for an ink/paper/printer
combination, I find using simulate paper white (and ink black) gives me the
most realistic simulation. In my case, since I don't have a spectro, my
curves just give me the most accurate picture of the tonal compression.

Tom Moore

> -----Original Message-----
> From: QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com] On
> Behalf Of John Wood
> Sent: Sunday, November 06, 2005 6:12 AM
> To: QuadtoneRIP@yahoogroups.com
> Subject: [QuadtoneRIP] Re: Confusion regarding Profiles and QTR
> 
> Thanks to both Toms (Moore and Husband).  Apart from the fact that I
> understand what is going on slightly more, I have use advice from
> both to fine tune my workflow.  I now convert to RGB-LAB in CS2 when
> working on the original image (just after conversion to B&W) and
> soft proof using QTR-RGB Matte.  My final output file in Qimage is
> saved with profile QTR-RGB Matte and the final print matches much
> closer what I see on screen than previously!
> 
> Another quesion this time re soft proofing.  Should one normally use
> the "Simulate Black Ink" option?  In my case I find the final print
> output is somewhere between the two (i.e. simulate on or simulate
> off) in terms of density of blacks.
> 
> Thanks again,

Apologies if I give two similar replies. At the time of the first 
reply I had not signed up yet an perhaps it does not appear.....

Hi Tom,

I'm still in the epxerimenting phase with QTR (windows XP, Photoshop 
CS2, Epson 2100, UC inks, Epson Enhanced Matte). With help of your 
excellent User Guide I have been able to get started very quickly.. 
Thanks!

There are however a few things that I can not get my head around yet. 
I found another recent thread that relates to it, but perhaps it fits 
better with this old post of yours.

I think by now I understand the "front-end" part of profiling. 
Convering to Gray-Lab linearizes the document and monitor (if 
properly calibrated) to the LAB space. Right?

What I don't understand yet is the "back-end"/printer part. I see 
also some differences between your workflow and Roy Harrington's flow 
as described in the "gray-readme.doc" file contained in the GTR 
installation.

When it comes to printing Roy states:

"For Windows where it is necessary to save a tiff-file, you should 
Convert to Profile using either the Gray Matte Paper or Gray Photo 
Paper. Then save the file for printing in QTR Gui".

I don't understand this. As I understand it, QTR linearizes against 
LAB. I would expect any differences between matte and glossy papers 
already to be accounted for in the QTR curves. So why would one need 
to convert before printing in QTR? 

I find support for this point of view in your workflow. I understand 
you use the Gray Matte and Gray Photo profiles for soft-proofing. But 
I don't see you actually saving a converted file fo printing. Am I 
correct?

To get some more understanding, I did two tests. For the first I 
printed a number of test wedges with Photoshop CS2 + QTR in different 
spaces (dot gain 20%, gamma 2.2, gray-lab) each of them both 
with "assign profile" and "convert to profile". To my surprise I did 
not see any difference whatsoever (visual inspection only, I have 
photospectrometer yet). In the second test I compared your workflow 
(as I understood it, so leaving the document converted to Gray-lab) 
and conversions to gray-matte and gray-photo. Again no visual 
differences (at least not to my untrained eye).

Should this test be correct indeed? Are do I miss something? If it's 
right it could explain why both your and Roy's workflow are correct. 
But then Roy's would be unnecessarily complex, which I find difficult 
to believe.

The good news is that my monitor and prints seem to match quite well. 
I have to do some more tests under better viewing circumstances. 


Sorry for the long post. It was already difficult to express my 
question in this way, let alone in shorter one ;-)

Thanks in advance,

Joost

I did some more testing and my puzzle seems to become a bit clearer.

I made the differences a bit bigger and printed 4 step wedges, dotgain 10% and dotgain 30%, each of them with the profile assigned and converted to that profile. Now I sees indeed differences between prints the converted files. By no means as huge as I expected based on what I saw on my monitor, but they are different. Now I know where to look I see the differences also in the less extreme cases. It learns me as well that I need really good light to inspect my prints I don't see differences in het prints of the assigned profile files, which is a confirmation that QTR does not use assigned profiles (as I read somewhere).

So this part of the mechanism becomes a bit clearer. Remains my question:

Why should I before printing convert to different profiles for matte and photo papers? Are these differences not already accounted for in the QTR curves?

Or are the matte and photo profiles only meant for soft-proofing?

Thanks

Joost

FYI: I did some more testing with test wedges and comparing of print 
against monitor. It looks like the prints of the gray-lab converted 
file match my monitor better than the gray-matte converted files (as 
said: printing on Epson Enhanced Matte). 

Again another reason NOT to convert to the gray-matte profile? But who 
am I to ignore the instructions of an expert like Roy? Am I right or do 
I miss something?

Joost

HI Joost,

Do what looks the best.  That's always the final answer!
Roy

On Tuesday, August 15, 2006, at 05:11  AM, horstenj wrote:

> FYI: I did some more testing with test wedges and comparing of print
> against monitor. It looks like the prints of the gray-lab converted
> file match my monitor better than the gray-matte converted files (as
> said: printing on Epson Enhanced Matte).
>
> Again another reason NOT to convert to the gray-matte profile? But who
> am I to ignore the instructions of an expert like Roy? Am I right or do
> I miss something?
>
> Joost
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
-
Roy Harrington
roy@...
Black & White Photo Gallery
http://www.harrington.com

--- In QuadtoneRIP@yahoogroups.com, Roy Harrington wrote:
>
> HI Joost,
>
> Do what looks the best. That's always the final answer!
> Roy
>

Thanks Roy,

That's a helpful answer. Trained as a scientist, I'm the type of guy that tries to understand. But apparently this is the point where science ends and art begins..... My mind can rest now...... I have QTR running, paid my license, made my first prints, got a (at least fairly decent) WYSIWG setup and I'm happy . Thanks for this great piece of software!

Joost