QTR-Quadtone RIP

"Conventional wisdom" for QTR seems to be to work in grayscale mode, 
but QTR also allows to work in and save in RGB mode. When I convert an 
RGB image to grayscale and apply Levels to set the black and white 
points, the resulting contrast is significantly less than when I stay 
in RGB mode, desaturate and apply Levels to set the black and white 
points. After Convert to Profile, save as tif and print with QTR this 
difference in contrast clearly shows in the prints.

So my question is: why would I ever want to convert to grayscale mode 
given these results, particularly since all my images are in RGB mode 
to begin with. And yes, I can always increase contrast after converting 
to grayscale, but why do this in the first place?

Because storage space is so cheap these days, the argument that the 
resulting grayscale files are smaller is not a very valid one in my 
opinion.

Frans Waterlander

Frans

The issue of conversion from colour to B&W is a complex one that has
engendered many long debates and discussions. A companion list to this
one, DigitalBlackandWhitethePrint has had several useful discussions
on this point. Also, there are many tool for B&W conversion providing
many options for contrast and conversion of various hues to different
tones.

The main reason for conversion to greyscale is not so much to reduce
file size, but rather to map colours in your image onto different
parts of the tonal range. The resulting image can still be an RGB file
or a greyscale file. Generally they should both appear and print the same.

The least favoured way of conversion is the PS Convert to Greyscale.
Desaturation of an image is often an improvement but doeson't offer
much flexibility. Another method with more flexibility is using the PS
Channel Mixer although I don't find it very convenient to use.
Currently I often use the so-called Gorman technique. A PS script for
it and a number of other conversion techniques can be found here:

   http://www.atncentral.com/download.htm#BW_Conv

Tom Moore

--- In QuadtoneRIP@yahoogroups.com, "fwaterlander" <frans2001@...> wrote:

>
> "Conventional wisdom" for QTR seems to be to work in grayscale mode, 
> but QTR also allows to work in and save in RGB mode. When I convert an 
> RGB image to grayscale and apply Levels to set the black and white 
> points, the resulting contrast is significantly less than when I stay 
> in RGB mode, desaturate and apply Levels to set the black and white 
> points. After Convert to Profile, save as tif and print with QTR this 
> difference in contrast clearly shows in the prints.
> 
> So my question is: why would I ever want to convert to grayscale mode 
> given these results, particularly since all my images are in RGB mode 
> to begin with. And yes, I can always increase contrast after converting 
> to grayscale, but why do this in the first place?
> 
> Because storage space is so cheap these days, the argument that the 
> resulting grayscale files are smaller is not a very valid one in my 
> opinion.
> 
> Frans Waterlander
>

Tom,

Thanks for your reply. I'm well aware of the different ways to 
convert an RGB image to grayscale mode. However, conversion to 
grayscale mode, at least to the best of my knowledge, causes a loss 
of contrast as compared to maintaining the RGB file as an RGB file 
and using Desaturate or Channel Mixer/Monochrome in Photoshop. So why 
does the QTR documentation suggest you convert to grayscale mode? QTR 
works just as well on RGB mode Desaturated or Channel 
Mixer/Monochrome images as long as you use Convert to Profile/QTR - 
RGB Matte Paper or /QTR - RGB Photo Paper before saving as tif.

Frans Waterlander

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@...> 
wrote:
>
> Frans
> 
> The issue of conversion from colour to B&W is a complex one that has
> engendered many long debates and discussions. A companion list to 
this
> one, DigitalBlackandWhitethePrint has had several useful discussions
> on this point. Also, there are many tool for B&W conversion 
providing
> many options for contrast and conversion of various hues to 
different
> tones.
> 
> The main reason for conversion to greyscale is not so much to reduce
> file size, but rather to map colours in your image onto different
> parts of the tonal range. The resulting image can still be an RGB 
file
> or a greyscale file. Generally they should both appear and print 
the same.
> 
> The least favoured way of conversion is the PS Convert to Greyscale.
> Desaturation of an image is often an improvement but doeson't offer
> much flexibility. Another method with more flexibility is using the 
PS
> Channel Mixer although I don't find it very convenient to use.
> Currently I often use the so-called Gorman technique. A PS script 
for
> it and a number of other conversion techniques can be found here:
> 
>    http://www.atncentral.com/download.htm#BW_Conv
> 
> Tom Moore
> 
> --- In QuadtoneRIP@yahoogroups.com, "fwaterlander" <frans2001@> 
wrote:
> >
> > "Conventional wisdom" for QTR seems to be to work in grayscale 
mode, 
> > but QTR also allows to work in and save in RGB mode. When I 
convert an 
> > RGB image to grayscale and apply Levels to set the black and 
white 
> > points, the resulting contrast is significantly less than when I 
stay 
> > in RGB mode, desaturate and apply Levels to set the black and 
white 
> > points. After Convert to Profile, save as tif and print with QTR 
this 
> > difference in contrast clearly shows in the prints.
> > 
> > So my question is: why would I ever want to convert to grayscale 
mode 
> > given these results, particularly since all my images are in RGB 
mode 
> > to begin with. And yes, I can always increase contrast after 
converting 
> > to grayscale, but why do this in the first place?
> > 
> > Because storage space is so cheap these days, the argument that 
the 
> > resulting grayscale files are smaller is not a very valid one in 
my 

> > opinion.
> > 
> > Frans Waterlander
> >
>

First, I have never noticed a loss of contrast when converting a
desaturated image to grayscale. Second, when the documentation was
written, QuadtoneRIP required a grayscale tiff as input. That has
since been relaxed.

Tom Moore

--- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander"
<frans2001@...> wrote:

>
> Tom,
> 
> Thanks for your reply. I'm well aware of the different ways to 
> convert an RGB image to grayscale mode. However, conversion to 
> grayscale mode, at least to the best of my knowledge, causes a loss 
> of contrast as compared to maintaining the RGB file as an RGB file 
> and using Desaturate or Channel Mixer/Monochrome in Photoshop. So why 
> does the QTR documentation suggest you convert to grayscale mode? QTR 
> works just as well on RGB mode Desaturated or Channel 
> Mixer/Monochrome images as long as you use Convert to Profile/QTR - 
> RGB Matte Paper or /QTR - RGB Photo Paper before saving as tif.
> 
> Frans Waterlander
> 
> --- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@> 
> wrote:
> >
> > Frans
> > 
> > The issue of conversion from colour to B&W is a complex one that has
> > engendered many long debates and discussions. A companion list to 
> this
> > one, DigitalBlackandWhitethePrint has had several useful discussions
> > on this point. Also, there are many tool for B&W conversion 
> providing
> > many options for contrast and conversion of various hues to 
> different
> > tones.
> > 
> > The main reason for conversion to greyscale is not so much to reduce
> > file size, but rather to map colours in your image onto different
> > parts of the tonal range. The resulting image can still be an RGB 
> file
> > or a greyscale file. Generally they should both appear and print 
> the same.
> > 
> > The least favoured way of conversion is the PS Convert to Greyscale.
> > Desaturation of an image is often an improvement but doeson't offer
> > much flexibility. Another method with more flexibility is using the 
> PS
> > Channel Mixer although I don't find it very convenient to use.
> > Currently I often use the so-called Gorman technique. A PS script 
> for
> > it and a number of other conversion techniques can be found here:
> > 
> >    http://www.atncentral.com/download.htm#BW_Conv
> > 
> > Tom Moore
> > 
> > --- In QuadtoneRIP@yahoogroups.com, "fwaterlander" <frans2001@> 
> wrote:
> > >
> > > "Conventional wisdom" for QTR seems to be to work in grayscale 
> mode, 
> > > but QTR also allows to work in and save in RGB mode. When I 
> convert an 
> > > RGB image to grayscale and apply Levels to set the black and 
> white 
> > > points, the resulting contrast is significantly less than when I 
> stay 
> > > in RGB mode, desaturate and apply Levels to set the black and 
> white 
> > > points. After Convert to Profile, save as tif and print with QTR 
> this 
> > > difference in contrast clearly shows in the prints.
> > > 
> > > So my question is: why would I ever want to convert to grayscale 
> mode 
> > > given these results, particularly since all my images are in RGB 
> mode 
> > > to begin with. And yes, I can always increase contrast after 
> converting 
> > > to grayscale, but why do this in the first place?
> > > 
> > > Because storage space is so cheap these days, the argument that 
> the 
> > > resulting grayscale files are smaller is not a very valid one in 
> my 
> > > opinion.
> > > 
> > > Frans Waterlander
> > >
> >
>

Tom,

There is indeed no loss of contrast when converting a desaturated 
image to grayscale, but there is a definite loss of contrast when 
converting an RGB color image to grayscale as compaired to 
desaturating an RGB image. So for an RGB image, it seems logical to 
me to NOT convert to grayscale but desaturate instead. That's my 
whole point here.

Frans Waterlander

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@...> 
wrote:
>
> First, I have never noticed a loss of contrast when converting a
> desaturated image to grayscale. Second, when the documentation was
> written, QuadtoneRIP required a grayscale tiff as input. That has
> since been relaxed.
> 
> Tom Moore
> 
> --- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander"
> <frans2001@> wrote:
> >
> > Tom,
> > 
> > Thanks for your reply. I'm well aware of the different ways to 
> > convert an RGB image to grayscale mode. However, conversion to 
> > grayscale mode, at least to the best of my knowledge, causes a 
loss 
> > of contrast as compared to maintaining the RGB file as an RGB 
file 
> > and using Desaturate or Channel Mixer/Monochrome in Photoshop. So 
why 
> > does the QTR documentation suggest you convert to grayscale mode? 
QTR 
> > works just as well on RGB mode Desaturated or Channel 
> > Mixer/Monochrome images as long as you use Convert to 
Profile/QTR - 
> > RGB Matte Paper or /QTR - RGB Photo Paper before saving as tif.
> > 
> > Frans Waterlander
> > 
> > --- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@> 
> > wrote:
> > >
> > > Frans
> > > 
> > > The issue of conversion from colour to B&W is a complex one 
that has
> > > engendered many long debates and discussions. A companion list 
to 
> > this
> > > one, DigitalBlackandWhitethePrint has had several useful 
discussions
> > > on this point. Also, there are many tool for B&W conversion 
> > providing
> > > many options for contrast and conversion of various hues to 
> > different
> > > tones.
> > > 
> > > The main reason for conversion to greyscale is not so much to 
reduce
> > > file size, but rather to map colours in your image onto 
different
> > > parts of the tonal range. The resulting image can still be an 
RGB 
> > file
> > > or a greyscale file. Generally they should both appear and 
print 
> > the same.
> > > 
> > > The least favoured way of conversion is the PS Convert to 
Greyscale.
> > > Desaturation of an image is often an improvement but doeson't 
offer
> > > much flexibility. Another method with more flexibility is using 
the 
> > PS
> > > Channel Mixer although I don't find it very convenient to use.
> > > Currently I often use the so-called Gorman technique. A PS 
script 
> > for
> > > it and a number of other conversion techniques can be found 
here:
> > > 
> > >    http://www.atncentral.com/download.htm#BW_Conv
> > > 
> > > Tom Moore
> > > 
> > > --- In QuadtoneRIP@yahoogroups.com, "fwaterlander" <frans2001@> 
> > wrote:
> > > >
> > > > "Conventional wisdom" for QTR seems to be to work in 
grayscale 
> > mode, 
> > > > but QTR also allows to work in and save in RGB mode. When I 
> > convert an 
> > > > RGB image to grayscale and apply Levels to set the black and 
> > white 
> > > > points, the resulting contrast is significantly less than 
when I 
> > stay 
> > > > in RGB mode, desaturate and apply Levels to set the black and 
> > white 
> > > > points. After Convert to Profile, save as tif and print with 
QTR 
> > this 
> > > > difference in contrast clearly shows in the prints.
> > > > 
> > > > So my question is: why would I ever want to convert to 
grayscale 
> > mode 
> > > > given these results, particularly since all my images are in 
RGB 
> > mode 
> > > > to begin with. And yes, I can always increase contrast after 
> > converting 
> > > > to grayscale, but why do this in the first place?
> > > > 
> > > > Because storage space is so cheap these days, the argument 
that 
> > the 
> > > > resulting grayscale files are smaller is not a very valid one 
in 

> > my 
> > > > opinion.
> > > > 
> > > > Frans Waterlander
> > > >
> > >
> >
>

Hi Frans.
I can't speak for others but it wouldn't have occurred to me to be
concerned over that issue. The reason being that I would never have a
reason for doing it anyway. It is a Photoshop issue not a QTR one. If
you use that method you are accepting whatever Photoshop wants to do
in the conversion. I prefer to control the conversions myself in so
far as my current skills allow. I'd be surprised to hear that folks
heavily involved with editing and printing B&W don't already know all
this, even as you apparently do. It's certainly not a documentation
issue for QTR. It's hard to discern where you are coming from with all
this.

It looks like your concerns and my somewhat ham handed responses to
them have initiated some actions toward trying to improve the basic
information for newcomers to QTR. That is all to the good, however,
it's unlikely to become so all inclusive as to explain all there is to
know about Color management and best Photoshop practices for B&W etc.
Some of this has to be assumed as part of the skill set held by the
prospective user. A lot of it is still shadowy stuff, I would
speculate, for most of us including me.

Let me tell you where I am coming from in this. Just as you eventually
did, I read and reread every bit of information that I found within
the QTR package. That was several years ago now. After I had done
that, in a few hours over the course of a couple of days I set up from
scratch QTR curves for a half dozen different papers and an ink set I
had diluted to grays myself. This was done for two printers that Roy
had provided drivers for but did not otherwise support with built in
curves. I then printed a few prints. One look at them and I
immediately e'mailed Roy and asked where to send a check. He responded
and I did so.

Now I am not some intellectual giant, yet it was possible for me to
manage to work out any puzzles I encountered in the process. I am, by
no means, an expert on any of this. I don't even like the word. It
brings to mind those learned people who held the prevailing views that
the earth was flat or that the universe revolved around it.

It would be wonderful if Roy and the "experts" were to write a
detailed book about every aspect of QTR and all the forknowledge
required to use it. I'd be the first to dive in and learn more but
would never think to demand it of them.

Once you or others are past the beginning stages of learning how to
use QTR, make some popcorn, type the word "Roy" into the group search
engine and sit back and review all his expressed wisdom through time
:-) Then pick out a few other names such as Stephen and do the same.
Yes, the search engine stinks, but it will work for this.

OK. Over and out. If I have offended anyone here it is not intentional
and I apologize.

Regards
Duane



--- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander"
<frans2001@...> wrote:

>
> Tom,
> 
> There is indeed no loss of contrast when converting a desaturated 
> image to grayscale, but there is a definite loss of contrast when 
> converting an RGB color image to grayscale as compaired to 
> desaturating an RGB image. So for an RGB image, it seems logical to 
> me to NOT convert to grayscale but desaturate instead. That's my 
> whole point here.
> 
> Frans Waterlander
> 

>

Hello Duane,

Some very crucial pieces of information, specific to QTR, are missing 
from the documentation. And, judging by some of the posts on this 
forum, I'm not the only one that has a hard time figuring it all out. 
This kind of feeling your way around is also a perfect breeding 
ground for developing bad habits.

One example: it is apparently not clear to everyone whether the last 
step before saving the file is to convert to gray lab space or to a 
particular paper profile. That should be crystal clear and it is not. 
And I could give more examples, but I guess you catch my drift.

Again, I think the program is great and well worth the money, but the 
documentation is in need of some serious revisions.

Frans Waterlander

--- In QuadtoneRIP@yahoogroups.com, "dlruckus" <dlruckus@...> wrote:
>
> Hi Frans.
> I can't speak for others but it wouldn't have occurred to me to be
> concerned over that issue. The reason being that I would never have 
a
> reason for doing it anyway. It is a Photoshop issue not a QTR one. 
If
> you use that method you are accepting whatever Photoshop wants to do
> in the conversion. I prefer to control the conversions myself in so
> far as my current skills allow. I'd be surprised to hear that folks
> heavily involved with editing and printing B&W don't already know 
all
> this, even as you apparently do. It's certainly not a documentation
> issue for QTR. It's hard to discern where you are coming from with 
all
> this.
> 
> It looks like your concerns and my somewhat ham handed responses to
> them have initiated some actions toward trying to improve the basic
> information for newcomers to QTR. That is all to the good, however,
> it's unlikely to become so all inclusive as to explain all there is 
to
> know about Color management and best Photoshop practices for B&W 
etc.
> Some of this has to be assumed as part of the skill set held by the
> prospective user. A lot of it is still shadowy stuff, I would
> speculate, for most of us including me.
> 
> Let me tell you where I am coming from in this. Just as you 
eventually
> did, I read and reread every bit of information that I found within
> the QTR package. That was several years ago now. After I had done
> that, in a few hours over the course of a couple of days I set up 
from
> scratch QTR curves for a half dozen different papers and an ink set 
I
> had diluted to grays myself. This was done for two printers that Roy
> had provided drivers for but did not otherwise support with built in
> curves. I then printed a few prints. One look at them and I
> immediately e'mailed Roy and asked where to send a check. He 
responded
> and I did so.
> 
> Now I am not some intellectual giant, yet it was possible for me to
> manage to work out any puzzles I encountered in the process. I am, 
by
> no means, an expert on any of this. I don't even like the word. It
> brings to mind those learned people who held the prevailing views 
that
> the earth was flat or that the universe revolved around it.
> 
> It would be wonderful if Roy and the "experts" were to write a
> detailed book about every aspect of QTR and all the forknowledge
> required to use it. I'd be the first to dive in and learn more but
> would never think to demand it of them.
> 
> Once you or others are past the beginning stages of learning how to
> use QTR, make some popcorn, type the word "Roy" into the group 
search
> engine and sit back and review all his expressed wisdom through time
> :-) Then pick out a few other names such as Stephen and do the same.
> Yes, the search engine stinks, but it will work for this.
> 
> OK. Over and out. If I have offended anyone here it is not 
intentional
> and I apologize.
> 
> Regards
> Duane
> 
> 
> 
> --- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander"
> <frans2001@> wrote:
> >
> > Tom,
> > 
> > There is indeed no loss of contrast when converting a desaturated 
> > image to grayscale, but there is a definite loss of contrast when 
> > converting an RGB color image to grayscale as compaired to 
> > desaturating an RGB image. So for an RGB image, it seems logical 
to 

> > me to NOT convert to grayscale but desaturate instead. That's my 
> > whole point here.
> > 
> > Frans Waterlander
> > 
> 
> >
>

fwaterlander wrote:

  When I convert an
> RGB image to grayscale and apply Levels to set the black and white 
> points, the resulting contrast is significantly less than when I stay 
> in RGB mode, desaturate and apply Levels to set the black and white 
> points. After Convert to Profile, save as tif and print with QTR this 
> difference in contrast clearly shows in the prints.

LIke mentioned by others I would suggest to use the channel 
mixer in PS and convert to grayscale there with the PS color 
settings combinations: AdobeRGB - gamma 2.2 or sRGB - gamma 
1.8 for greyscale. There shouldn't be a change in contrast or 
gamma then. Check the values with the L(ab) window in Info. 
There could be some visual shifts at the ends when colors are 
pronounced at the ends of the range and they convert to 
lighter or darker tones with the channel mixer settings. At 
least you have control with this method. Any other tone 
corrections can/should be done in greyscale afterwards and the 
image saved as such with gamma 2.2 for example. Just for 
printing the conversion to the suitable QTR 
printer/matte/gloss/paper profile is used and the image is not 
archived but goes in the bin after printing. Where I have 
written gamma 2.2 you could use QTR Gray-lab profile instead.

If you use PWP as an image editor then all bets are off when 
you do conversions to QTR profiles. In general there are some 
flaws in its CM whether you select Microsoft's color engine or 
the LCMS engine. If you print through Qimage you better stay 
in RGB when the QTR (RGB) profiles are used in Qimage's CM or 
switch the CM off and load a printer ready (prepared in PS) 
image in Qimage.


Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

Ernst,

Thanks for your reply. I think there may be some confusion about the 
use of the term grayscale. For instance, when I use the Channel Mixer 
and check the Monochrome box, I get a monochrome RGB image (three 
channels, R, G and B and all pixels have the same R, G and B values), 
not a grayscale, single channel image. As long as I keep my image in 
the RGB mode, the Gray settings in Photoshop Color Settings don't 
come into play. When you say that any other tone corrections should 
be done in grayscale afterwards implies that you change the mode from 
RGB to Gray and my point is that you don't have to do that at all and 
stay in RGB mode "till the bitter end".

I don't want to nitpick or repeat what I have said in other posts, 
but your recommendation to select either Gray Gamma 1.8 or Gray Gamma 
2.2 for the Gray Working Space is inconsistent with Roy's to use QTR -
 Gray Lab (if you don't want to use the RGB mode). And that's an 
issue that I see a lot on this forum: recommendations that are 
inconsistent and/or contradictory. I rest my case for an overhaul of 
the documentation.

Best regards en de groetjes,

Frans Waterlander

--- In QuadtoneRIP@yahoogroups.com, Ernst Dinkla <E.Dinkla@...> wrote:
>
> fwaterlander wrote:
> 
>   When I convert an
> > RGB image to grayscale and apply Levels to set the black and 
white 
> > points, the resulting contrast is significantly less than when I 
stay 
> > in RGB mode, desaturate and apply Levels to set the black and 
white 
> > points. After Convert to Profile, save as tif and print with QTR 
this 

> > difference in contrast clearly shows in the prints.
> 
> LIke mentioned by others I would suggest to use the channel 
> mixer in PS and convert to grayscale there with the PS color 
> settings combinations: AdobeRGB - gamma 2.2 or sRGB - gamma 
> 1.8 for greyscale. There shouldn't be a change in contrast or 
> gamma then. Check the values with the L(ab) window in Info. 
> There could be some visual shifts at the ends when colors are 
> pronounced at the ends of the range and they convert to 
> lighter or darker tones with the channel mixer settings. At 
> least you have control with this method. Any other tone 
> corrections can/should be done in greyscale afterwards and the 
> image saved as such with gamma 2.2 for example. Just for 
> printing the conversion to the suitable QTR 
> printer/matte/gloss/paper profile is used and the image is not 
> archived but goes in the bin after printing. Where I have 
> written gamma 2.2 you could use QTR Gray-lab profile instead.
> 
> If you use PWP as an image editor then all bets are off when 
> you do conversions to QTR profiles. In general there are some 
> flaws in its CM whether you select Microsoft's color engine or 
> the LCMS engine. If you print through Qimage you better stay 
> in RGB when the QTR (RGB) profiles are used in Qimage's CM or 
> switch the CM off and load a printer ready (prepared in PS) 
> image in Qimage.
> 
> 
> Met vriendelijke groeten,  Ernst
> 
> 
> |  Dinkla Grafische Techniek  |
> |     www.pigment-print.com    |
> |             ( unvollendet )            |
>

--- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander" <frans2001@...> 
wrote:

> I don't want to nitpick or repeat what I have said in other posts, 
> but your recommendation to select either Gray Gamma 1.8 or Gray Gamma 
> 2.2 for the Gray Working Space is inconsistent with Roy's to use QTR -
>  Gray Lab (if you don't want to use the RGB mode). And that's an 
> issue that I see a lot on this forum: recommendations that are 
> inconsistent and/or contradictory. I rest my case for an overhaul of 
> the documentation.

Frans,

As you know, I have expressed my sympathy with you that it would be 
handy if the documentation would be updated to avoid unnecesaary 
confusion and discussions like us. As also discussed that has to be 
done not by Roy of Stephen, but by us, this community of which you're 
now becoming part of if you want.

But please, don't press it too far. I sympathize as well with Duane's 
comments to you. You just will have to invest time and effort yourself 
to master the basics. Even with an updated QTR manual, the issues you 
address now will NOT be addressed. These ARE PS/color management issues 
and NOT QTR issues. Ernst's suggestions are not necessarily 
inconsistent with other workflows since there are many roads that lead 
to Rome (actually not sure this is a proper Englisch saying, but as 
former Dutch guy you'll understand ;-) ).

Joost
 

Joost

Frans Waterlander wrote:
> Ernst,
> 
> Thanks for your reply. I think there may be some confusion about the 
> use of the term grayscale. For instance, when I use the Channel Mixer 
> and check the Monochrome box, I get a monochrome RGB image (three 
> channels, R, G and B and all pixels have the same R, G and B values), 
> not a grayscale, single channel image. As long as I keep my image in 
> the RGB mode, the Gray settings in Photoshop Color Settings don't 
> come into play. When you say that any other tone corrections should 
> be done in grayscale afterwards implies that you change the mode from 
> RGB to Gray and my point is that you don't have to do that at all and 
> stay in RGB mode "till the bitter end".

I didn't mention that last monochrome RGB>Greyscale step, but 
that's the one where no shifts in contrast and gamma should 
occur so where you should use compatible colorspace-gamma 
settings or at least know what you are doing. Whether you have 
to do that last step to greyscale or not is a matter of what 
you like to archive, a 3x bigger file or not. It is about what 
  you like for further editing, in greyscale or in color. If 
you think that you should edit  all in color before switching 
to greyscale (if ever) than that certainly is another approach 
than I use, I wouldn't trust myself in doing that.

> I don't want to nitpick or repeat what I have said in other posts, 
> but your recommendation to select either Gray Gamma 1.8 or Gray Gamma 
> 2.2 for the Gray Working Space is inconsistent with Roy's to use QTR -
>  Gray Lab (if you don't want to use the RGB mode). 

There's hardly a difference between Gray Gamma 2.2 and 
QTR-Gray Lab in practice. I use QTR's Gray Lab. Steve Kale 
uses Gamma 2.2 and a lot of other skilled digital B&W printers 
do the last too. The Gray Lab should be a fraction more 
perceptually correct but both the quality of your monitor's 
calibration and to what it is calibrated is more important. 
When you convert to the QTR paper profiles from 2.2 or Gray 
Lab you get the perceptual curve for the tone range of that 
paper and that is the really important last step. Where you 
see inconsistency there isn't one in practice.

On documentation I could agree but I'm no volunteer either for 
that. When you grow slowly into digital B&W printing and were 
part of the development by commenting, trial and error, 
suggestions in the lists, DIY attempts in your own shop you 
understand that QTR's documentation is just a small part of 
the learning process. That learning process goes along 
different routes for users, what seems logical to one isn't to 
the other. Different expectations of what should be available 
in shareware software is another one. Lately I see some 
messages on more lists where newcomers express a lack of 
patience for that learning curve combined with a critical mood 
on what is available. There was an artisan skill and thorough 
knowledge needed in the wet darkroom for good printing and I 
believe that applies to digital printing too. It wasn't  "you 
press the button and we do the rest" in the past and it isn't 
right now, not to speak of the many extra buttons we have 
today. The ordinary consumer is still amazed when his digital 
pictures appear wirelessly on the display, the "developed" 
pictures fall on the doormat but the underlying complexity and 
what has to be done to make the best print has nothing of that 
simplicity right now and I wonder it will ever be like that.

And that's an
> issue that I see a lot on this forum: recommendations that are 
> inconsistent and/or contradictory. I rest my case for an overhaul of 
> the documentation.

There's no contradiction in my opinion, there may be some 
confusion about what could be contradicting. This forum is the 
best digital B&W printing forum you will find on this planet. 
You have to do with it like we all do.


Met vriendelijke groeten,  Ernst


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