Digital BW, The Print

George,

it's great to "see" you here. Thanks for joining our inaugural discussions. You 
raised a whole bunch of hot issues each of which calls for a new thread. 
I'll start with the scan workflow. You wrote:

>>>
Scanning protocols are also problematical. Silverfast is the only 
third pary scanning software that allows you to make your own 
LUT's. I've fooled around and come up with N+1, N-1 and N+2 
LUT's, and they work well - in 8 bit, of course. Both Mike Kravit 
and I scan in 16, drop down into 8 bit Silverfast HDR and 
optimize the image before it even gets into Photoshop. What do 
you guys do at the scanning stage? What works consistenly?<<<

While I see the point of scanning in 16bit, I don't see that as necessary a 
priori. It seems to me a matter of whether or not you have enough control in 
the scanner interface to let the scanner  spit out an 8bit file where the tones 
are laid out as best they can  without local controls. The Crosfield at BowHaus 
in Los Angeles, only outputs 8bits, for example, but they are "great" 8bits, 
because of how it's driven. 

With less capable scanners and drivers, the 16bit is a workaround t o allow 
Photoshop to do the heavy lifting. That's all I see in it for now. All this may 
change if Adobe implements 16bits across everything.

However, considering that the upcoming release of PiezoBW software will 
allow for 16bit printing on the desktop, there will be the dilemma: If you didn't 
scan it in 16bit and _stayed_ in 16bit, what's the use? Which means that the 
brave printer must scan in 16, do all the other maneuvers needed to fake 
layers and masks and produce a printing file without ever dropping to 8. For 
some who need only one overall move, this may be the ideal and highest 
possible quality. I suspect, for most, it will not be used untill Photoshop 
embraces 16 more fully.

Here now is a workflow idea (8 or 16bits)  that I would like to post for feedback 
and comments:  

-The scan of the negative or other monochrome original is done in RGB (8 or 
16) and  saved out of the scanner software with the appropriate profile. 

- The file is opened in photoshop for tonal adjustments while still in RGB. But 
before starting, we check our color settings (this assumes PS 6). 
----Under gray we have created a curve that matches the paper/ink/printer we 
intend to use. That means that a _grayscale file_ on screen will look identical 
to a print made under those settings. 
----Under RGB we set the same color space that the file came from, so that the 
intentions of the scanner and our view in PS match. The only real critical 
number here is the gamma.

- We now do global and local adjustments as needed while still in RGB mode. 
The critical step in this workflow is to stay in RGB. At this point we have the 
option to add a channel mixer set to mono as the top layer (if in 8bits) which 
does 2 things: Helps us see a consistent gray-color image, and allows us to 
pick whatever mix of scanner channels looks best (more important for CCD 
users).

- After we are happy with the look of the image, we make a dupe of the file, 
flatten (if it was 8bits) and convert to grayscale. We notice that the file looks 
exactly the same in grayscale as it did in RGB. What in fact has happened is 
that Photoshop has internally "adapted" the RGB file to the Gray settings we 
previously set, which compensated for our paper/ink/printer. It is like putting it 
through a custom profile made for our specific output.

- We now take that grayscale and go to piezo and print with no further 
adjustments. I bet that histogram will look pretty damn good now.

We have gained several things from this simultaneous drop to gray and match 
the output device.

-We have a master file in RGB from which subsequent gray files can be made 
for different papers just as one would for color. Alternatively,  a neutral 
conversion can be produced (for other uses), based on a gray gamma that 
simply matches the RGB gamma of the file.
- We have used all the information our scanner is capable of by utilizing all its 
channels with whatever benefits they each may have in noise, sharpness etc.
- We have done no moves in the fragile 8bit gray mode. We stand a chance at 
a better histogram depending on whether we move all 3 channels at once or 
separately.

That's the general idea: work in RGB, drop to a pre-calibrated gray when done 
and print with no other tweaks.

I hope we can compare notes on the above.

Antonis Ricos

Bonsoir Benoit,

nice to "see" you visit us here. Well, I suppose none of us had a wild part=
y or a 
hot date tonight...     Is that a _sign_ of maturity?    ...... sigh!

<bg>

Antonis 

--- In DigitalBlackandWhiteThePrint@y..., Benoit Malphettes <Benoit@s...> 
wrote:
> Thanks Martin to invite me to this newsgroup, I already sent a note to
> invite PhilBard here and I see that Antonis is already here! Good people.=
 So
> hi, everyone!
> mmm…is it a sigh of maturity  to be here on a Saturday evening LOL
>  
> Benoît

Benoit,

Well lets see Saturday night was..... Hmmm....52 yrs old......married 
for 23 years.......what are they for again?

Thanks for stopping by and letting Phil Bard know about the list.

Martin

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:
> Bonsoir Benoit,
> 
> nice to "see" you visit us here. Well, I suppose none of us had a 
wild part=
> y or a 
> hot date tonight...     Is that a _sign_ of maturity?    ...... 
sigh!
> 
> <bg>
> 
> Antonis 
> 
> --- In DigitalBlackandWhiteThePrint@y..., Benoit Malphettes 
<Benoit@s...> 
> wrote:
> > Thanks Martin to invite me to this newsgroup, I already sent a 
note to
> > invite PhilBard here and I see that Antonis is already here! Good 
people.=
>  So
> > hi, everyone!
> > mmm…is it a sigh of maturity  to be here on a Saturday evening LOL
> >  
> > Benoît

Both!

Steadman

  ----- Original Message ----- 
  From: Benoit Malphettes 
  To: 'DigitalBlackandWhiteThePrint@yahoogroups.com' 
  Sent: Sunday, July 29, 2001 12:26 AM
  Subject: RE: [DigitalBlackandWhiteThePrint] Scanning workflow for BW


  Sign not sigh!!!!

   

  Beno�t

   

  -----Original Message-----
  From: Benoit Malphettes [mailto:Benoit@...]
  Sent: Saturday, July 28, 2001 10:26 PM
  To: 'DigitalBlackandWhiteThePrint@yahoogroups.com'
  Subject: RE: [DigitalBlackandWhiteThePrint] Scanning workflow for BW

   

  Thanks Martin to invite me to this newsgroup, I already sent a note to invite PhilBard here and I see that Antonis is already here! Good people. So hi, everyone!

  mmm�is it a sigh of maturity  to be here on a Saturday evening LOL

   

  Beno�t

   

  -----Original Message-----
  From: antonisphoto@... [mailto:antonisphoto@...]
  Sent: Saturday, July 28, 2001 10:09 PM
  To: DigitalBlackandWhiteThePrint@yahoogroups.com
  Subject: [DigitalBlackandWhiteThePrint] Scanning workflow for BW

   

  George,

  it's great to "see" you here. Thanks for joining our inaugural discussions. You 
  raised a whole bunch of hot issues each of which calls for a new thread. 
  I'll start with the scan workflow. You wrote:

  >>>
  Scanning protocols are also problematical. Silverfast is the only 
  third pary scanning software that allows you to make your own 
  LUT's. I've fooled around and come up with N+1, N-1 and N+2 
  LUT's, and they work well - in 8 bit, of course. Both Mike Kravit 
  and I scan in 16, drop down into 8 bit Silverfast HDR and 
  optimize the image before it even gets into Photoshop. What do 
  you guys do at the scanning stage? What works consistenly?<<<

  While I see the point of scanning in 16bit, I don't see that as necessary a 
  priori. It seems to me a matter of whether or not you have enough control in 
  the scanner interface to let the scanner  spit out an 8bit file where the tones 
  are laid out as best they can  without local controls. The Crosfield at BowHaus 
  in Los Angeles, only outputs 8bits, for example, but they are "great" 8bits, 
  because of how it's driven. 

  With less capable scanners and drivers, the 16bit is a workaround t o allow 
  Photoshop to do the heavy lifting. That's all I see in it for now. All this may 
  change if Adobe implements 16bits across everything.

  However, considering that the upcoming release of PiezoBW software will 
  allow for 16bit printing on the desktop, there will be the dilemma: If you didn't 
  scan it in 16bit and _stayed_ in 16bit, what's the use? Which means that the 
  brave printer must scan in 16, do all the other maneuvers needed to fake 
  layers and masks and produce a printing file without ever dropping to 8. For 
  some who need only one overall move, this may be the ideal and highest 
  possible quality. I suspect, for most, it will not be used untill Photoshop 
  embraces 16 more fully.

  Here now is a workflow idea (8 or 16bits)  that I would like to post for feedback 
  and comments:  

  -The scan of the negative or other monochrome original is done in RGB (8 or 
  16) and  saved out of the scanner software with the appropriate profile. 

  - The file is opened in photoshop for tonal adjustments while still in RGB. But 
  before starting, we check our color settings (this assumes PS 6). 
  ----Under gray we have created a curve that matches the paper/ink/printer we 
  intend to use. That means that a _grayscale file_ on screen will look identical 
  to a print made under those settings. 
  ----Under RGB we set the same color space that the file came from, so that the 
  intentions of the scanner and our view in PS match. The only real critical 
  number here is the gamma.

  - We now do global and local adjustments as needed while still in RGB mode. 
  The critical step in this workflow is to stay in RGB. At this point we have the 
  option to add a channel mixer set to mono as the top layer (if in 8bits) which 
  does 2 things: Helps us see a consistent gray-color image, and allows us to 
  pick whatever mix of scanner channels looks best (more important for CCD 
  users).

  - After we are happy with the look of the image, we make a dupe of the file, 
  flatten (if it was 8bits) and convert to grayscale. We notice that the file looks 
  exactly the same in grayscale as it did in RGB. What in fact has happened is 
  that Photoshop has internally "adapted" the RGB file to the Gray settings we 
  previously set, which compensated for our paper/ink/printer. It is like putting it 
  through a custom profile made for our specific output.

  - We now take that grayscale and go to piezo and print with no further 
  adjustments. I bet that histogram will look pretty damn good now.

  We have gained several things from this simultaneous drop to gray and match 
  the output device.

  -We have a master file in RGB from which subsequent gray files can be made 
  for different papers just as one would for color. Alternatively,  a neutral 
  conversion can be produced (for other uses), based on a gray gamma that 
  simply matches the RGB gamma of the file.
  - We have used all the information our scanner is capable of by utilizing all its 
  channels with whatever benefits they each may have in noise, sharpness etc.
  - We have done no moves in the fragile 8bit gray mode. We stand a chance at 
  a better histogram depending on whether we move all 3 channels at once or 
  separately.

  That's the general idea: work in RGB, drop to a pre-calibrated gray when done 
  and print with no other tweaks.

  I hope we can compare notes on the above.

  Antonis Ricos







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[Non-text portions of this message have been removed]

Folks, I decided to repeat what I posted in the "early days" of this list (like a 
week ago!! <s>) under message 24, because no one picked up the thread - 
and perhaps no one was _here_ to pick it up. I was prompted to do this by 
Todd's recent post about breaks in the 3/4 tones. Please read on:
------------------------------------------

Here now is a workflow idea (8 or 16bits)  that I would like to post for
feedback and comments:  

-The scan of the negative or other monochrome original is done in RGB (8 or 
16) and  saved out of the scanner software with the appropriate profile. If it is 
an existing gs file, it can be thrown into RGB mode (with careful choices in the 
gray and RGB color settings).

- The file is then opened in photoshop for tonal adjustments while still in RGB. 
But  before starting, we check our color settings (the following assumes PS 6): 
a)----Under gray we have created a curve that matches the paper/ink/printer 
we intend to use. That means that a _grayscale file_ on screen will look 
identical to a print made under those settings. 
b)----Under RGB we set the same color space that the file came from, so that 
the intentions of the scanner and our view in PS match. The only real critical 
number here is the gamma.

- We now do global and local adjustments as needed while still in RGB mode. 
 At this point we have the option to add a channel mixer set to mono as the top 
layer (if in 8bits) which does 2 things: Helps us see a consistent gray-color 
image, and allows us to pick whatever mix of scanner channels looks best 
(more important for CCD users).

- After we are happy with the look of the image, we make a dupe of the file, 
flatten (if it was 8bits) and convert to grayscale. We now notice that the file
looks exactly the same in grayscale as it did in RGB. What in fact has 
happened is that Photoshop has internally "adapted" the RGB file to the Gray 
settings we previously set, which compensated for our paper/ink/printer. It is 
like putting it through a custom profile made for our specific output.

- We now take that grayscale and print with no further adjustments.

There may be several benefits to this:

-We have a master file in RGB from which subsequent gray files can be made 
for different papers just as one would for color (through profiles). 
- We have used all the information our scanner is capable of by utilizing all
its channels with whatever benefits they each may have in noise, sharpness 
etc.
- We have done no moves in the fragile 8bit gray mode. We stand a chance at 
a better histogram (depending on whether we move all 3 channels at once or 
separately).

That's the general idea: work in RGB, drop to a pre-calibrated gray when done 
and print with no other tweaks. This may help with the situation Todd was 
describing - but is also a good workflow that allows quick alternate files for 
different print settings without re-curving each file.

I hope we can compare notes on the above.

Antonis Ricos

Antonis,

I am not quite following the workflow here so I have inserted some 
questions:

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:
(sniP)
> 
> Here now is a workflow idea (8 or 16bits)  that I would like to 
post for
> feedback and comments:  
> 
> -The scan of the negative or other monochrome original is done in 
RGB (8 or 
> 16) and  saved out of the scanner software with the appropriate 
profile. If it is 
> an existing gs file, it can be thrown into RGB mode (with careful 
choices in the 
> gray and RGB color settings).
> 
> - The file is then opened in photoshop for tonal adjustments while 
still in RGB. 
> But  before starting, we check our color settings (the following 
assumes PS 6): 
> a)----Under gray we have created a curve that matches the 
paper/ink/printer 
> we intend to use. That means that a _grayscale file_ on screen will 
look 
> identical to a print made under those settings. 
> b)----Under RGB we set the same color space that the file came 
from, so that 
> the intentions of the scanner and our view in PS match. The only 
real critical 
> number here is the gamma.

You are setting a custom curve for grayscale I assume by printing out 
a step wedge and visually calibrating the screen to match. But if you 
are working in a RGB space even with a channel layer set to mono 
would the custom grayscale curve apply?

> 
> - We now do global and local adjustments as needed while still in 
RGB mode. 
>  At this point we have the option to add a channel mixer set to 
mono as the top 
> layer (if in 8bits) which does 2 things: Helps us see a consistent 
gray-color 
> image, and allows us to pick whatever mix of scanner channels looks 
best 
> (more important for CCD users).

Is there enough difference between the channels to provide useable 
information at the print level?

As a thought, what if you modified the gamma of each channel slightly 
to increase the difference between them?
> 
> - After we are happy with the look of the image, we make a dupe of 
the file, 
> flatten (if it was 8bits) and convert to grayscale. We now notice 
that the file
> looks exactly the same in grayscale as it did in RGB. What in fact 
has 
> happened is that Photoshop has internally "adapted" the RGB file to 
the Gray 
> settings we previously set, which compensated for our 
paper/ink/printer. It is 
> like putting it through a custom profile made for our specific 
output.

Okay so this is the answer to my first question. In the mode change 
Photoshop is also performing a conversion from one profile to another.

> 
> - We now take that grayscale and print with no further adjustments.
> 
> There may be several benefits to this:
> 
> -We have a master file in RGB from which subsequent gray files can 
be made 
> for different papers just as one would for color (through 
profiles). 
> - We have used all the information our scanner is capable of by 
utilizing all
> its channels with whatever benefits they each may have in noise, 
sharpness 
> etc.
> - We have done no moves in the fragile 8bit gray mode. We stand a 
chance at 
> a better histogram (depending on whether we move all 3 channels at 
once or 
> separately).

I am beginning to wonder if the 8-bit space is as fragile as we have 
been thinking. After doing some identical manipulations of raw scans 
at 16 and 8 bit to the point of heavy combing of the 8-bit histogram 
I am not seeing any difference in the print quality. Not to say that 
there would not be a difference at some point but a bad 8-bit 
histogram does not automatically mean a bad print. It may mean you 
are getting close to the edge of posterizing but that edge may be 
image dependent.

Todd should jump in here as he has been giving me these terrible 
ideas.

> 
> That's the general idea: work in RGB, drop to a pre-calibrated gray 
when done 
> and print with no other tweaks. This may help with the situation 
Todd was 
> describing - but is also a good workflow that allows quick 
alternate files for 
> different print settings without re-curving each file.

The theory is sound but I don't know how much you are really getting 
in print quality at the end because of the very close similarity 
between the three channels to start with. You are also paying a 
performance price in working with the bigger files.

My feeling is that for a normal negative requiring moderate 
adjustment there might be no gain but for manipulating a difficult or 
marginal negative perhaps. Really need to try it from scan to print 
both ways and see if there is a detectable benefit.

Martin

> 
> I hope we can compare notes on the above.
> 
> Antonis Ricos

on 8/11/01 12:53 AM, mwesley250@... wrote:

>> - We now do global and local adjustments as needed while still in
> RGB mode. 
>> At this point we have the option to add a channel mixer set to
> mono as the top 
>> layer (if in 8bits) which does 2 things: Helps us see a consistent
> gray-color 
>> image, and allows us to pick whatever mix of scanner channels looks
> best 
>> (more important for CCD users).
> 
> Is there enough difference between the channels to provide useable
> information at the print level?
> 
> As a thought, what if you modified the gamma of each channel slightly
> to increase the difference between them?

You could put a Curves adjustment layer below your Channel Mixer adj. layer.
If you mess with each channel's curves independent of one another, you can
alter the characteristics of the channels before you mix them. Not sure I
know if there is merit in doing this, but you COULD. ;-)

Antonis, I'm also curious about your custom grayscale curve for display
purposes. This is a custom dot gain setting you create in Color Settings?
And do you set this as your grayscale working space, or apply it as a
profile to your image? Is this in addition to monitor calibration, or in
lieu of it. If your monitor is calibrated, shouldn't your print profiles be
putting your prints in the ball park?

Todd

Martin,

Here's one way to work with large files (+100MB) comfortably.  From the 
raw scan, res down to a small file size, 10 to 20 MB, and save 
separately. Then add your adjustment layers for curves and levels, with 
masks if needed, etc., as many as you desire, to get the look you want.  
Then create a "layer set" for all of the added layers above the 
background, and res *back up* (yes, you heard correctly) to the exact 
same pixel size of the original.  Then simply drag the _set_ from the 
layers palette into the original file's window holding down the shift 
key (so it will center up correctly) and all of your adjustment layers 
will now reside in the larger file.  If you don't res back up, none of 
the adjustment layers will scale correctly.  Then you are ready to do 
any cloning or other manipulations necessary.

Works great...

Phil
http://philbard.com

> The theory is sound but I don't know how much you are really getting 
> in print quality at the end because of the very close similarity 
> between the three channels to start with. You are also paying a 
> performance price in working with the bigger files.
> 
> My feeling is that for a normal negative requiring moderate 
> adjustment there might be no gain but for manipulating a difficult or 
> marginal negative perhaps. Really need to try it from scan to print 
> both ways and see if there is a detectable benefit.

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:

> You are setting a custom curve for grayscale I assume by printing out 
> a step wedge and visually calibrating the screen to match.

---Correct


 But if you 
> are working in a RGB space even with a channel layer set to mono 
> would the custom grayscale curve apply?

----No. Not while in RGB. It will apply at the moment of transition from RGB to 
gray. You can set up ways to preview, but that's not the issue here.

> Is there enough difference between the channels to provide useable 
> information at the print level?

----- That depends on the specifics of the scanner.

> 
> As a thought, what if you modified the gamma of each channel slightly 
> to increase the difference between them?

---- Possibly. Or a for a given tweak you may only use one or two channels.

>  In the mode change 
> Photoshop is also performing a conversion from one profile to another.

---- Correct!
 
> I am beginning to wonder if the 8-bit space is as fragile as we have 
> been thinking. After doing some identical manipulations of raw scans 
> at 16 and 8 bit to the point of heavy combing of the 8-bit histogram 
> I am not seeing any difference in the print quality. Not to say that 
> there would not be a difference at some point but a bad 8-bit 
> histogram does not automatically mean a bad print. It may mean you 
> are getting close to the edge of posterizing but that edge may be 
> image dependent.

----- That's exactly my understanding too. If you have a subtle gradation over a 
long distance - say a clear sky that goes from 11 to 18% percent - you are 
more likely to notice a difference. Even then, nothing a little noise couldn't fix. 
Even 2% noise will fill in a gap-toothed histo.

> The theory is sound but I don't know how much you are really getting 
> in print quality at the end because of the very close similarity 
> between the three channels to start with. You are also paying a 
> performance price in working with the bigger files.
> 
> My feeling is that for a normal negative requiring moderate 
> adjustment there might be no gain but for manipulating a difficult or 
> marginal negative perhaps. Really need to try it from scan to print 
> both ways and see if there is a detectable benefit.

---- It isn't so much about the 3 channels or the histogram as much as it is 
about the distortion introduced in the workflow when working in grayscale and 
have already calibrated to a printed reference by adjusting the gray curve (in 
the color prefs).
The minute you change that gray curve for an alternate use, your whole 
dodge-and-burn goes out the window because it was done for that specific ink 
and paper.
The other benefits are secondary; though, considering Paul's RGB workflow, 
I'd say the whole grayscale thing should stay in RGB.

Antonis

--- In DigitalBlackandWhiteThePrint@y..., Todd Flashner <tflash@e...> wrote:
> on 8/11/01 12:53 AM, mwesley250@e... wrote:

> You could put a Curves adjustment layer below your Channel Mixer adj. 
layer.

--- You are right: The Mixer should always be at the top.

> Antonis, I'm also curious about your custom grayscale curve for display
> purposes. This is a custom dot gain setting you create in Color Settings?
> And do you set this as your grayscale working space, or apply it as a
> profile to your image? Is this in addition to monitor calibration, or in
> lieu of it. If your monitor is calibrated, shouldn't your print profiles be
> putting your prints in the ball park?

---Todd, monitor calib is separate from all this: This is a profile that tells PS 
what RGB values to give the monitor for whatever it is displaying, be it RGB, 
gray or CMYK. 
What the Custom Dot Gain curve (PS 6) does is tell photoshop to display gray 
values according to how they will print. So, you can put up an image and a 
print made from it and fiddle with the  custom gray curve (in color settings) 
until the two match. Then you save that and name it for the printing system you 
calibrated to. You can save as many as you have ink/paper combos. Next time 
you have a grayscale file you load the custom dot gain curve for the ink/paper 
you intend to print on. It will tell you exactly how it looks before you print.

When you use a printing profile in Piezo, that profile does a set of tonal 
adjustments internally to compensate for the paper. It "linearizes" the process 
so to speak, so that 15% gray will be 15% across all sorts of papers (one 
profile to each paper). 
In practice, as you know we mix and match profiles and papers. So, whatever 
the profile does, that's great, but we only really care about the final print. After 
a print is made, on the specific paper, profile, ink, printer etc, then we make 
that Custom Dot Gain that accounts for the whole lot and gives us a perfect 
preview. At least that's one way of working.

Antonis

>> Is there enough difference between the channels to provide useable
>> information at the print level?
>> 
>> As a thought, what if you modified the gamma of each channel slightly
>> to increase the difference between them?
> 
> You could put a Curves adjustment layer below your Channel Mixer adj. layer.
> If you mess with each channel's curves independent of one another, you can
> alter the characteristics of the channels before you mix them. Not sure I
> know if there is merit in doing this, but you COULD. ;-)


Sorry Martin, I see my reply to you was merely redundant to your question. I
think my answer was based upon remembering that in the past I've found it
useful to slap a "false" set of curves on an image to aid in creating an
alpha mask from one of the channels.
 
Todd

Martin,

what Phil is saying works exactly as described and a very good idea. 

Just a caveat:
The safest bet for this method is to limit layers to adjustment layers and masks. 
If you use pieces of the image and channel calculations and the like, you'll 
have a hell of a time replacing all the pieces with the same taken from the raw 
scan after resing up.

Antonis



--- In DigitalBlackandWhiteThePrint@y..., "Phil Bard" <phil@p...> wrote:

> Martin,
> 
> Here's one way to work with large files (+100MB) comfortably.  From the 
> raw scan, res down to a small file size, 10 to 20 MB, and save 
> separately. Then add your adjustment layers for curves and levels, with 
> masks if needed, etc., as many as you desire, to get the look you want.  
> Then create a "layer set" for all of the added layers above the 
> background, and res *back up* (yes, you heard correctly) to the exact 
> same pixel size of the original.  Then simply drag the _set_ from the 
> layers palette into the original file's window holding down the shift 
> key (so it will center up correctly) and all of your adjustment layers 
> will now reside in the larger file.  If you don't res back up, none of 
> the adjustment layers will scale correctly.  Then you are ready to do 
> any cloning or other manipulations necessary.
> 
> Works great...
> 
> Phil
> http://philbard.com

Okay, I'm tying to do it, but it doesn't seem to be working. I'm in Color
Settings, I use the Grayscale Working Space dropdown menu and choose Custom
Dot Gain. But as I adjust the curve, I see my little layer masks icons
change, but not the image itself. The other time I tried it I saw the color
swatches of my swatch pallet change, but not the image. What could I be
doing wrong?

Todd

> ---Todd, monitor calib is separate from all this: This is a profile that tells
> PS 
> what RGB values to give the monitor for whatever it is displaying, be it RGB,
> gray or CMYK. 
> What the Custom Dot Gain curve (PS 6) does is tell photoshop to display gray
> values according to how they will print. So, you can put up an image and a
> print made from it and fiddle with the  custom gray curve (in color settings)
> until the two match. Then you save that and name it for the printing system
> you 
> calibrated to. You can save as many as you have ink/paper combos. Next time
> you have a grayscale file you load the custom dot gain curve for the ink/paper
> you intend to print on. It will tell you exactly how it looks before you
> print.
> 
> When you use a printing profile in Piezo, that profile does a set of tonal
> adjustments internally to compensate for the paper. It "linearizes" the
> process 
> so to speak, so that 15% gray will be 15% across all sorts of papers (one
> profile to each paper).
> In practice, as you know we mix and match profiles and papers. So, whatever
> the profile does, that's great, but we only really care about the final print.
> After 
> a print is made, on the specific paper, profile, ink, printer etc, then we
> make 
> that Custom Dot Gain that accounts for the whole lot and gives us a perfect
> preview. At least that's one way of working.
> 
> Antonis

> background, and res *back up* (yes, you heard correctly) to the exact 
> same pixel size of the original.  

What you mean by "res back up" ?

Phil,

That's a really great idea and one, which would really save me a lot 
o waiting time. I have been scanning my 6x7 negs to get 550MB, 48-bit 
RGB files. I do some adjustments and then drop to 24-bit RGB which 
gives me about a 200-250 MB file and I would like to adjust in RGB 
space as long as possible but even with 1.5GB of RAM and a 1.2 GHz 
CPU this still gets slow. The sample down, work, sample up should get 
me working at a file size where the system will really move.

Is there any limit on how small you go down and do you then have to 
do any tweaking once you are back to the original with the ressed up 
layers?

Thanks,

Martin

P.S. How did the enlargement neg from A&I come out or is the process 
still under development?


--- In DigitalBlackandWhiteThePrint@y..., "Phil Bard" <phil@p...> 
wrote:
> Martin,
> 
> Here's one way to work with large files (+100MB) comfortably.  From 
the 
> raw scan, res down to a small file size, 10 to 20 MB, and save 
> separately. Then add your adjustment layers for curves and levels, 
with 
> masks if needed, etc., as many as you desire, to get the look you 
want.  
> Then create a "layer set" for all of the added layers above the 
> background, and res *back up* (yes, you heard correctly) to the 
exact 
> same pixel size of the original.  Then simply drag the _set_ from 
the 
> layers palette into the original file's window holding down the 
shift 
> key (so it will center up correctly) and all of your adjustment 
layers 
> will now reside in the larger file.  If you don't res back up, none 
of 
> the adjustment layers will scale correctly.  Then you are ready to 
do 
> any cloning or other manipulations necessary.
> 
> Works great...
> 
> Phil
> http://philbard.com
> 
> 
> > The theory is sound but I don't know how much you are really 
getting 
> > in print quality at the end because of the very close similarity 
> > between the three channels to start with. You are also paying a 
> > performance price in working with the bigger files.
> > 
> > My feeling is that for a normal negative requiring moderate 
> > adjustment there might be no gain but for manipulating a 
difficult or 
> > marginal negative perhaps. Really need to try it from scan to 
print 
> > both ways and see if there is a detectable benefit.

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:
> --- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:
> 
> > You are setting a custom curve for grayscale I assume by printing 
out 
> > a step wedge and visually calibrating the screen to match.
> 
> ---Correct

I find that frustrating. Is there an empirical way to do a match? 
Densitometer readings of printed step wedge to curve?

>  But if you 
> > are working in a RGB space even with a channel layer set to mono 
> > would the custom grayscale curve apply?
> 
> ----No. Not while in RGB. It will apply at the moment of transition 
from RGB to 
> gray. You can set up ways to preview, but that's not the issue here.

Do you need to preview or will the on screen view be faithfully 
translated into the new space with profile conversion?

> 
> > Is there enough difference between the channels to provide 
useable 
> > information at the print level?
> 
(snip earlier)
>  
> > I am beginning to wonder if the 8-bit space is as fragile as we 
have 
> > been thinking. After doing some identical manipulations of raw 
scans 
> > at 16 and 8 bit to the point of heavy combing of the 8-bit 
histogram 
> > I am not seeing any difference in the print quality. Not to say 
that 
> > there would not be a difference at some point but a bad 8-bit 
> > histogram does not automatically mean a bad print. It may mean 
you 
> > are getting close to the edge of posterizing but that edge may be 
> > image dependent.
> 
> ----- That's exactly my understanding too. If you have a subtle 
gradation over a 
> long distance - say a clear sky that goes from 11 to 18% percent - 
you are 
> more likely to notice a difference. Even then, nothing a little 
noise couldn't fix. 
> Even 2% noise will fill in a gap-toothed histo.

Thanks for the tip on using noise! 

> 
(snip)

> >Really need to try it from scan to print 
> > both ways and see if there is a detectable benefit.
> 
> ---- It isn't so much about the 3 channels or the histogram as much 
as it is 
> about the distortion introduced in the workflow when working in 
grayscale and 
> have already calibrated to a printed reference by adjusting the 
gray curve (in 
> the color prefs).

Could you clarify the distortion issue for me? Is this distortion 
caused by the manipulation of the smaller set of data, 8 vs 24 bit?

> The minute you change that gray curve for an alternate use, your 
whole 
> dodge-and-burn goes out the window because it was done for that 
specific ink 
> and paper.

Should you have a whole set of Custom curves, one for each paper? 
Could you imbed the specific curve for that image into the file?

> The other benefits are secondary; though, considering Paul's RGB 
workflow, 
> I'd say the whole grayscale thing should stay in RGB.

I am wondering how that would work with my RGB pyro scans where I do 
have a lot of difference on the Blue channel.

Martin

--- In DigitalBlackandWhiteThePrint@y..., Todd Flashner <tflash@e...> 
wrote:
> 
> 
> >> Is there enough difference between the channels to provide 
useable
> >> information at the print level?
> >> 
> >> As a thought, what if you modified the gamma of each channel 
slightly
> >> to increase the difference between them?
> > 
> > You could put a Curves adjustment layer below your Channel Mixer 
adj. layer.
> > If you mess with each channel's curves independent of one 
another, you can
> > alter the characteristics of the channels before you mix them. 
Not sure I
> > know if there is merit in doing this, but you COULD. ;-)
> 
> 
> Sorry Martin, I see my reply to you was merely redundant to your 
question. I
> think my answer was based upon remembering that in the past I've 
found it
> useful to slap a "false" set of curves on an image to aid in 
creating an
> alpha mask from one of the channels.

I think by doing this you get the illusion that you are adding 
something to the file but in reality you are just pushing arround the 
original scan data. It might be useful for final quality but have to 
try it out.

"False"set of curves for alpha mask?? I'm not following you.

Martin

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:
> Martin,
> 
> what Phil is saying works exactly as described and a very good 
idea. 
> 
> Just a caveat:
> The safest bet for this method is to limit layers to adjustment 
layers and masks. 
> If you use pieces of the image and channel calculations and the 
like, you'll 
> have a hell of a time replacing all the pieces with the same taken 
from the raw 
> scan after resing up.

Antonis, even with the masks to you risk a loss of registration 
quality by making the mask in low res and then ressing back up?

Martin

(snip)

Todd,

The problem may be in how you opened the 21-step file and how you 
responded to the profile dialog box. My main computer is apart and I 
can't check but go back a try a different path to bring the image 
into PS.

Martin

--- In DigitalBlackandWhiteThePrint@y..., Todd Flashner <tflash@e...> 
wrote:
> Okay, I'm tying to do it, but it doesn't seem to be working. I'm in 
Color
> Settings, I use the Grayscale Working Space dropdown menu and 
choose Custom
> Dot Gain. But as I adjust the curve, I see my little layer masks 
icons
> change, but not the image itself. The other time I tried it I saw 
the color
> swatches of my swatch pallet change, but not the image. What could 
I be
> doing wrong?
> 
> Todd
> 
> 
> > ---Todd, monitor calib is separate from all this: This is a 
profile that tells
> > PS 
> > what RGB values to give the monitor for whatever it is 
displaying, be it RGB,
> > gray or CMYK. 
> > What the Custom Dot Gain curve (PS 6) does is tell photoshop to 
display gray
> > values according to how they will print. So, you can put up an 
image and a
> > print made from it and fiddle with the  custom gray curve (in 
color settings)
> > until the two match. Then you save that and name it for the 
printing system
> > you 
> > calibrated to. You can save as many as you have ink/paper combos. 
Next time
> > you have a grayscale file you load the custom dot gain curve for 
the ink/paper
> > you intend to print on. It will tell you exactly how it looks 
before you
> > print.
> > 
> > When you use a printing profile in Piezo, that profile does a set 
of tonal
> > adjustments internally to compensate for the paper. 
It "linearizes" the
> > process 
> > so to speak, so that 15% gray will be 15% across all sorts of 
papers (one
> > profile to each paper).
> > In practice, as you know we mix and match profiles and papers. 
So, whatever
> > the profile does, that's great, but we only really care about the 
final print.
> > After 
> > a print is made, on the specific paper, profile, ink, printer 
etc, then we
> > make 
> > that Custom Dot Gain that accounts for the whole lot and gives us 
a perfect

> > preview. At least that's one way of working.
> > 
> > Antonis

Martin,

I haven't had a problem working down as low as 4 MB.  I suspect it 
won't matter since it's scalable technology you're dealing with.  Maybe 
2 pixels by 2 pixels is going to give you trouble- ha.  Just don't do 
anything but curves and levels, certainly no layers that are not 
adjustment layers, or it will cause problems res'ing back up.

I'm still awaiting the second round of negs from A&I.  I think they are 
busting their butts to get a good result here, I know Chip has 
rescanned a couple of times to try to obtain a higher level of 
sharpness.  He called yesterday and said he's off to get married and 
honeymoon, but the Lightjet operator Jim is on it and will call.  
Hopefully next week I'll have some results, but I'm going to be at 
Siggraph so I won't make any promises.  Rest assured we will have 
something soon, however, and the list will be the first to know.

Phil
http://philbard.com

> Phil,
> 
> That's a really great idea and one, which would really save me a lot 
> o waiting time. I have been scanning my 6x7 negs to get 550MB, 48-bit 
> RGB files. I do some adjustments and then drop to 24-bit RGB which 
> gives me about a 200-250 MB file and I would like to adjust in RGB 
> space as long as possible but even with 1.5GB of RAM and a 1.2 GHz 
> CPU this still gets slow. The sample down, work, sample up should get 
> me working at a file size where the system will really move.
> 
> Is there any limit on how small you go down and do you then have to 
> do any tweaking once you are back to the original with the ressed up 
> layers?
>

Andre,

Suppose you have a 10,000 x 10,000 pixel original (about 100 MB 
Grayscale).  If you "res down" (resample) to 2000 x 2000 you will have 
about a 4 MB file.  Then do the layer work, then go into Image Size and 
resample the file back up to 10,000 x 10,000.  That would be "res'ing 
up."  In reality you would never want to use an image that was res'ed 
up, since you would only be enlarging the pixels, not adding true 
resolution or detail.  But it acts to resize the adjustment layers and 
any masking you have done.  Otherwise they will be too small and only 
affect a 2000 x 2000 area of your larger image. You actually can throw 
the smaller sized image file away after getting the layer set back out 
of it and into the original.

BTW, this works in reverse.  Say you are working on a large file, and 
have already added some adjustment layers, and you find that after 5 or 
6 the file size has grown significantly and everything is slowing down.  
Copy the raw image, usually its in the background layer unless you've 
moved it up, to a new file.  Keep it the same size pixelwise for now.  
Then link all the adjustment layers in the first file and create a new 
layer set containing them.  Drag this into the newly created image file 
holding down the shift key to center it up.  Then resample that file 
down to a smaller size.  All the layers will shrink with the image, and 
you should be able to continue your manipulations much more quickly.  
When done, res back up to the precise pixel dimensions of the original, 
then make a new layer set containing all original and any added 
adjustment layers.  Before you take them back to the original hi-res 
file, you must delete or at least turn off all adjustment layers there, 
or duplication will result.  Then drag the new set in and you're back 
in business...

Hope this helps,
Phil
http://philbard.com

> 
> > background, and res *back up* (yes, you heard correctly) to the exact 
> > same pixel size of the original.  
> 
> What you mean by "res back up" ?

on 8/11/01 12:34 PM, mwesley250@... wrote:

>> Martin,
>> 
>> what Phil is saying works exactly as described and a very good
> idea. 
>> 
>> Just a caveat:
>> The safest bet for this method is to limit layers to adjustment
> layers and masks.
>> If you use pieces of the image and channel calculations and the
> like, you'll 
>> have a hell of a time replacing all the pieces with the same taken
> from the raw 
>> scan after resing up.
> 
> Antonis, even with the masks to you risk a loss of registration
> quality by making the mask in low res and then ressing back up?
> 
> Martin


Your mask's edges may get a little rough. Usually a little gaussian blur,
and perhaps a little gamma move on the masks, takes care if it.

Todd

on 8/11/01 12:31 PM, mwesley250@... wrote:

>> Sorry Martin, I see my reply to you was merely redundant to your
> question. I
>> think my answer was based upon remembering that in the past I've
> found it
>> useful to slap a "false" set of curves on an image to aid in
> creating an
>> alpha mask from one of the channels.
> 
> I think by doing this you get the illusion that you are adding
> something to the file but in reality you are just pushing arround the
> original scan data. It might be useful for final quality but have to
> try it out.
> 
> "False"set of curves for alpha mask?? I'm not following you.
> 
> Martin

By "false" I mean that they are not really corrective for the image, but
they are just for accomplishing a specific task, then tossed.

For instance, if you want to take a color channel and dupe it to make a
mask, your channels will be different depending on what layer is active at
the time, and what adjustment layers are active above it.

While there is a lot you can do to any channel just by treating it like a
grayscale image, and working on it directly, with adjustment layers you can
alter it before you even start to work on it. Curves was but one example.

Say you have a head with wispy hair you want to make a mask for. Which
channel will be better (more contrast) to work from may depend on the color
of the persons skin, and hair, and the color of the background. Rather than
just working with the best channel of the image before any adjustments are
made, you could add an adjustment layer of some sort, to accentuate the
difference between the subject and background color. Take the case of
Caucasian skin and blond hair against a red background. There may or may not
be good luminosity contrast between subject and background due to lighting,
but as subject and foreground are both comprised predominantly of red, there
will not be a lot of separation due to color contrast. A preliminary
selective color move, or an increase in saturation, on the image might give
you a better channel to start making your mask from.

So, when you work on a color channel directly, you only have grayscale tools
available to you, but if you work on a color channel through the image
itself (the composite channel), you have a broader tool set to work with.

Todd

on 8/11/01 12:38 PM, mwesley250@... wrote:

> Todd,
> 
> The problem may be in how you opened the 21-step file and how you
> responded to the profile dialog box. My main computer is apart and I
> can't check but go back a try a different path to bring the image
> into PS.
> 
> Martin

Oh, I was watching an already opened image as I was making the changes in
the Color Settings.

I think I prefer your idea of applying the curve as an adjustment layer.
Much more flexible. Easy to change as you change papers, etc.

Todd

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:

> > > You are setting a custom curve for grayscale I assume by printing 
> out 
> > > a step wedge and visually calibrating the screen to match.
> > 
> > ---Correct
> 
> I find that frustrating. Is there an empirical way to do a match? 
> Densitometer readings of printed step wedge to curve?


-----Martin, this is why there is such a thing as a Gain calculation in the printing 
industry. Any service bureau or printer uses a densitometer to calculate 
Density Gain at different points in the scale. 
Here is how it works: 
The instrument is "shown" the paper white and asked to call it 0% - regardless 
of the actual density (which could be 0.06, for example).
Then, it is shown the maximum black and asked to call it 100% - again 
regardless of whether it is 1.65, or 2.2 or whatever.
After the endpoints have been "fed" to the instrument, it determines all points 
in between in percents. So if you read the 5% patch and you get 6%, you 
have a 1% gain. The 85% may well be 95% etc. The darks have more gain 
usually.

The mathematics behind that are based on halftone thinking: A 50% gray, for 
example is defined as any area where half is filled with black ink and the other 
half is paper white. The black half could be broken up by a halftone screen of 
any frequency desired.

Now, when you visit the Custom Dot Gain dialogue in PS6, it will make a lot 
more sense: You are expected to plug in the %numbers by which a given 
theoretical % actually prints. So when you put, say, 90 in the 80% window, 
you are telling the program that our black coverage for that area is 10% more 
than we intend. A square made up of 80% black ink will in fact end up with 
90% ink.

I'll take up your other questions separately, because this is getting a bit long 
as a single post.

Antonis

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:

> >  But if you 
> > > are working in a RGB space even with a channel layer set to mono 
> > > would the custom grayscale curve apply?
> > 
> > ----No. Not while in RGB. It will apply at the moment of transition 
> from RGB to 
> > gray. You can set up ways to preview, but that's not the issue here.
> 
> Do you need to preview or will the on screen view be faithfully 
> translated into the new space with profile conversion?
> 
----- You don't really need the preview just for the grayscale - it will be faithfully 
translated as you say. But if you expect to preview color (as in split toned etc), 
that's another story. You need a profile to use under Proof setup>custom. 



> > ---- It isn't so much about the 3 channels or the histogram as much 
> as it is 
> > about the distortion introduced in the workflow when working in 
> grayscale and 
> > have already calibrated to a printed reference by adjusting the 
> gray curve (in 
> > the color prefs).
> 
> Could you clarify the distortion issue for me? Is this distortion 
> caused by the manipulation of the smaller set of data, 8 vs 24 bit?

The "distortion" comes from kinks in the Custom Dot Gain curve. Because it is 
custom (presumably for a given paper, ink,printer combo) it is likely to be less 
smooth than a gamma 1.8, 2.2 or x% dot gain which only uses a midtone 
mark. If you manipulate your gray scale while that CDG curve is loaded you 
are doing all your moves based on that curve. A new paper combo and your 
moves are meaningless (more or less depending on how different your new 
curve is).


> 
> Should you have a whole set of Custom curves, one for each paper? 

---- Yes.


> Could you imbed the specific curve for that image into the file?

----- You can save the file with the profile (=your CDG curve) embedded. You 
can even convert to a different profile for a different paper down the line - but 
then you are begging for tonal breaks in the file - which is kind of the point of 
the workflow I am suggesting here.


> I am wondering how that would work with my RGB pyro scans where I do 
> have a lot of difference on the Blue channel.

------ That's an interesting point that I haven't explored. Whenever you have an 
RGB scan for grayscale there is no reason to assume that every density on the 
film is given the exact same digital value for all three channels. Think about it 
as a three-pass scan. Then add the RGB filters. No one is obliged to use all 
three "passes" the same way. You can set one channel up for better shadow 
separation, one for better highlights etc. Can be a lot of fun!  (and give you a 
more meaningful 3x8=24 bit grayscale). Ah, where is Austin when we need 
him!... <g>

Antonis

--- In DigitalBlackandWhiteThePrint@y..., Todd Flashner <tflash@e...> 
wrote:
> on 8/11/01 12:38 PM, mwesley250@e... wrote:
> 
> > Todd,
> > 
> > The problem may be in how you opened the 21-step file and how you
> > responded to the profile dialog box. My main computer is apart 
and I
> > can't check but go back a try a different path to bring the image
> > into PS.
> > 
> > Martin
> 
> Oh, I was watching an already opened image as I was making the 
changes in
> the Color Settings.

Todd,

The changes in the Custom Dot Gain curve will not be visible in the 
on screen image unless the profile of the image matched the Working 
Space profile. So if you opened a file with a Dot Gain 20% profile 
and your working space is Gamma 2.2 the image will be uneffected by 
the changes to the Custom Dot Gain curve.

Martin

> 
> I think I prefer your idea of applying the curve as an adjustment 
layer.
> Much more flexible. Easy to change as you change papers, etc.

That may have been someone elses idea but sounds interesting. Then 
there are the Proof Setup option too.

Martin

Phil,

4 MB! I will have to give this a try. 

Thanks for the info and the update on the project with A&I.

Martin

--- In DigitalBlackandWhiteThePrint@y..., "Phil Bard" <phil@p...> 
wrote:
> Martin,
> 
> I haven't had a problem working down as low as 4 MB.  I suspect it 
> won't matter since it's scalable technology you're dealing with.  
Maybe 
> 2 pixels by 2 pixels is going to give you trouble- ha.  Just don't 
do 
> anything but curves and levels, certainly no layers that are not 
> adjustment layers, or it will cause problems res'ing back up.
> 
> I'm still awaiting the second round of negs from A&I.  I think they 
are 
> busting their butts to get a good result here, I know Chip has 
> rescanned a couple of times to try to obtain a higher level of 
> sharpness.  He called yesterday and said he's off to get married 
and 
> honeymoon, but the Lightjet operator Jim is on it and will call.  
> Hopefully next week I'll have some results, but I'm going to be at 
> Siggraph so I won't make any promises.  Rest assured we will have 
> something soon, however, and the list will be the first to know.
> 
> Phil
> http://philbard.com
(snip)

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:

(snip)
> 
> Now, when you visit the Custom Dot Gain dialogue in PS6, it will 
make a lot 
> more sense: You are expected to plug in the %numbers by which a 
given 
> theoretical % actually prints. So when you put, say, 90 in the 80% 
window, 
> you are telling the program that our black coverage for that area 
is 10% more 
> than we intend. A square made up of 80% black ink will in fact end 
up with 
> 90% ink.

Antonis,

I guess I am wondering if you printed out a step wedge containing the 
13 values in the Custom Dot Gain curve dialog box, could you then 
measure them off the print with a densitometer and then calculate the 
appropriate values to enter into the Custom Curve? And if you can, 
would it give you any greater boost in screen-to-print calibration 
accuracy then just eyballing it?

Martin

(snip)

Martin and Todd,

this is why it's a good idea to:

1- have PS ask you what to do when you open a file with an embedded profile 
that doesn't match the working profile (or no profile at all).

2- check to see what is the profile status of the image under 
image>mode>assign profile. (You also get a hint from the star (*) or  pound (#) 
following the color space in the title of the window).

Antonis

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:

> Todd,
> 
> The changes in the Custom Dot Gain curve will not be visible in the 
> on screen image unless the profile of the image matched the Working 
> Space profile. So if you opened a file with a Dot Gain 20% profile 
> and your working space is Gamma 2.2 the image will be uneffected by 
> the changes to the Custom Dot Gain curve.
> 
> Martin

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:
> Antonis,
> 
> I guess I am wondering if you printed out a step wedge containing the 
> 13 values in the Custom Dot Gain curve dialog box, could you then 
> measure them off the print with a densitometer and then calculate the 
> appropriate values to enter into the Custom Curve? 

----Yes. As long as you follow my earlier description of the differences 
between pure density reads (0.00-4.00) and "relative" reads (0-100%).


And if you can, 
> would it give you any greater boost in screen-to-print calibration 
> accuracy then just eyballing it?

---- It should. But it could also be overkill, depending on how stable everything 
else in your system is day-to-day. You may prefer to have a standard file with 
a full tonal range and at the beginning of a new session, make a print and 
check it against a known Dot Curve. I mostly eyeball for grayscales and use 
the instruments for color.


Antonis


Antonis

--- In DigitalBlackandWhiteThePrint@y..., antonisphoto@y... wrote:

(snip)

> And if you can, 
> > would it give you any greater boost in screen-to-print 
calibration 
> > accuracy then just eyballing it?
> 
> ---- It should. But it could also be overkill, depending on how 
stable everything 
> else in your system is day-to-day. You may prefer to have a 
standard file with 
> a full tonal range and at the beginning of a new session, make a 
print and 
> check it against a known Dot Curve. I mostly eyeball for grayscales 
and use 
> the instruments for color.

Some of us have better eyeballs of course. I have to confess to 
taking a print to where I like it on screen, printing it, and from 
then on start to ignore the monitor. I start doing adjustments to the 
image file based on what I see in the print. Like I do in the 
darkroom. This feels intuitive but I wonder if I am wasting paper in 
an ink this way. This is probably unavoidable in the final tweaking 
stage.

Thanks,
Martin