Digital BW, The Print

I have discovered that the soft proofing is different in 2.3.2 than it 
was in 2.3.0, as follows:

In 2.3.0, paper color can be selected but this does not automatically 
select ink color.  This is a very accurate soft proof.  It is not 
possible with any combination of soft proof settings to select ink 
color.

In 2.3.1, when paper color is selected, ink color is automatically 
selected.  There is no way to select paper color without ink color.

With Epson canned color profiles, soft proofing works as with 2.3.0.

Regardless of what has been said, the ink-color-checked soft proof does 
not provide an accurate soft proof of the print output with regard to 
darker tones.  Having looked at BW photographs for 40 years, I am quite 
confident of that.

Do you mean simulate black ink instead of "ink color" in the  
softproof dialog (CS2) ?  Also, I agree that checking simulate paper  
color and/or black ink when softproofing  is not at all realistic  
(even when looking away to avoid brain tricks).  Just doesn't cut it  
for me.  Like putting a fog layer over the image.  I get excellent  
screen/print matches with neither of these options checked, using a  
calibrated Apple LCD monitor.

Carl

> I have discovered that the soft proofing is different in 2.3.2 than it
> was in 2.3.0, as follows:
>
> In 2.3.0, paper color can be selected but this does not automatically
> select ink color.  This is a very accurate soft proof.  It is not
> possible with any combination of soft proof settings to select ink
> color.
>
> In 2.3.1, when paper color is selected, ink color is automatically
> selected.  There is no way to select paper color without ink color.
>
> With Epson canned color profiles, soft proofing works as with 2.3.0.
>
> Regardless of what has been said, the ink-color-checked soft proof  
> does
> not provide an accurate soft proof of the print output with regard to
> darker tones.  Having looked at BW photographs for 40 years, I am  
> quite
> confident of that.

Sorry-- Yes, by "ink color" I mean "simulate black ink."


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl Schofield 
<scho@m...> wrote:
>
> Do you mean simulate black ink instead of "ink color" in the  
> softproof dialog (CS2) ?  Also, I agree that checking simulate 
paper  
> color and/or black ink when softproofing  is not at all realistic  
> (even when looking away to avoid brain tricks).  Just doesn't cut 
it  
> for me.  Like putting a fog layer over the image.  I get excellent  
> screen/print matches with neither of these options checked, using 
a  
> calibrated Apple LCD monitor.
> 
> Carl
> 
> 
> > I have discovered that the soft proofing is different in 2.3.2 
than it
> > was in 2.3.0, as follows:
> >
> > In 2.3.0, paper color can be selected but this does not 
automatically
> > select ink color.  This is a very accurate soft proof.  It is not
> > possible with any combination of soft proof settings to select ink
> > color.
> >
> > In 2.3.1, when paper color is selected, ink color is automatically
> > selected.  There is no way to select paper color without ink 
color.
> >
> > With Epson canned color profiles, soft proofing works as with 
2.3.0.
> >
> > Regardless of what has been said, the ink-color-checked soft 
proof  
> > does
> > not provide an accurate soft proof of the print output with 
regard to
> > darker tones.  Having looked at BW photographs for 40 years, I 
am  

> > quite
> > confident of that.
>

Walt

> 
> In 2.3.1, when paper color is selected, ink color is automatically
> selected.  There is no way to select paper color without ink color.
>

This is the same with the GM i1 Photo profiles.  If you select Simulate
Paper Color then Simulate Ink Black is automatically and irreversibly
checked (except by unchecking Simulate Paper Color).  One can Simulate Ink
Black without simulating paper color but not the other way around.
Interestingly, the Epson provided profiles (Mac 4800 driver) don't allow you
to Simulate Ink Black at all.

We're not sure what Adobe does when you check these settings, what it looks
for etc. I know this is one area where Roy would like to know more - for
obvious reasons.  

> Regardless of what has been said, the ink-color-checked soft proof does
> not provide an accurate soft proof of the print output with regard to
> darker tones.  Having looked at BW photographs for 40 years, I am quite
> confident of that.
> 

BTW on a properly calibrated display, unless either (a) your display's black
point is as weak and exactly the same as ink on the paper you are looking
at, or (b) you are not illuminating your print with the same lighting as was
done using the profile ie D50, then it is simply not possible that the two
can have the same black without checking Simulate Black Ink (when allowed).
As we have discussed many times this is not an exact science though and a
multitude of things (such as other colours in the filed of view) go into the
mix.  As I noted a day or so ago I also found the black point shift to be "a
lot" but in line with a GM generated colour profile for the same paper (ie I
gained comfort that at least QTR ICC appeared to generate the same look as a
GM profile).  I put the print vs display difference down to the very real
fact that my print viewing conditions are not D50.  In fact they are far
from it.  I have halogen ceiling lighting that is probably at best
3100Kelvin.  Hence the recent discussion on Solux bulbs.  In 3100K lighting
the prints will look considerably darker than soft proofed display.

Cheers

Steve

Steve -

Thanks.

Yes, I too noted that the Epson profiles do not allow simulate ink 
color.

My display calibration is good (i1) at 65K/2.2.  I am viewing the 
monitor in a semi-darkened room, which makes the blacks more intense, 
and they are quite good I think.  My print viewing is at 5K (measures 
actually 4950) and 450-500 lux.  

I am going to try working up a new print from scratch with the soft 
proof and simulate ink color and see what I come up with for a 
print.  It will be too contrasty I think, an effort to comensate for 
the "unrealistically" weak monitor blacks shown in soft proof.  I'll 
see.

Having just looked at the Epson canned profile for VFA (which allows 
paper white without ink black), I might just use that!  I need the 
paper white for a good soft proof and I don't need the paper black. 

I am surprised that a profile itself dictates these PS settings--
sounds like differences in the format rather than just the correction 
curve.  But I don't know what I'm talking about on this score.

Walt


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale 
<stevekale@b...> wrote:
>
> Walt
> 
> > 
> > In 2.3.1, when paper color is selected, ink color is automatically
> > selected.  There is no way to select paper color without ink 
color.
> >
> 
> This is the same with the GM i1 Photo profiles.  If you select 
Simulate
> Paper Color then Simulate Ink Black is automatically and 
irreversibly
> checked (except by unchecking Simulate Paper Color).  One can 
Simulate Ink
> Black without simulating paper color but not the other way around.
> Interestingly, the Epson provided profiles (Mac 4800 driver) don't 
allow you
> to Simulate Ink Black at all.
> 
> We're not sure what Adobe does when you check these settings, what 
it looks
> for etc. I know this is one area where Roy would like to know more -
 for
> obvious reasons.  
> 
> > Regardless of what has been said, the ink-color-checked soft 
proof does
> > not provide an accurate soft proof of the print output with 
regard to
> > darker tones.  Having looked at BW photographs for 40 years, I am 
quite
> > confident of that.
> > 
> 
> BTW on a properly calibrated display, unless either (a) your 
display's black
> point is as weak and exactly the same as ink on the paper you are 
looking
> at, or (b) you are not illuminating your print with the same 
lighting as was
> done using the profile ie D50, then it is simply not possible that 
the two
> can have the same black without checking Simulate Black Ink (when 
allowed).
> As we have discussed many times this is not an exact science though 
and a
> multitude of things (such as other colours in the filed of view) go 
into the
> mix.  As I noted a day or so ago I also found the black point shift 
to be "a
> lot" but in line with a GM generated colour profile for the same 
paper (ie I
> gained comfort that at least QTR ICC appeared to generate the same 
look as a
> GM profile).  I put the print vs display difference down to the 
very real
> fact that my print viewing conditions are not D50.  In fact they 
are far
> from it.  I have halogen ceiling lighting that is probably at best
> 3100Kelvin.  Hence the recent discussion on Solux bulbs.  In 3100K 
lighting

> the prints will look considerably darker than soft proofed display.
> 
> Cheers
> 
> Steve
>

I have to agree that I don't particularly like either of the Simulate check boxes.
These are both Photoshop features not ICC features.  There is no info about
what PS is really doing with these.  The only thing that the ICC profile has in it
that I think is relevant is the media white-point and black-point.  These are
just the values read for the paper white and the darkest ink patch.

The major difference between 2.3.0 and 2.3.2 is that the former used a single
gray transfer tag so soft-proof really didn't show anything.  The new one uses
the color lookup tables which have two curves -- a gray one for printing and a
color one for the softproofing.

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl Schofield <scho@m...> 
wrote:

>
> Do you mean simulate black ink instead of "ink color" in the  
> softproof dialog (CS2) ?  Also, I agree that checking simulate paper  
> color and/or black ink when softproofing  is not at all realistic  
> (even when looking away to avoid brain tricks).  Just doesn't cut it  
> for me.  Like putting a fog layer over the image.  I get excellent  
> screen/print matches with neither of these options checked, using a  
> calibrated Apple LCD monitor.
> 
> Carl
> 
> 
> > I have discovered that the soft proofing is different in 2.3.2 than it
> > was in 2.3.0, as follows:
> >
> > In 2.3.0, paper color can be selected but this does not automatically
> > select ink color.  This is a very accurate soft proof.  It is not
> > possible with any combination of soft proof settings to select ink
> > color.
> >
> > In 2.3.1, when paper color is selected, ink color is automatically
> > selected.  There is no way to select paper color without ink color.
> >
> > With Epson canned color profiles, soft proofing works as with 2.3.0.
> >
> > Regardless of what has been said, the ink-color-checked soft proof  
> > does
> > not provide an accurate soft proof of the print output with regard to
> > darker tones.  Having looked at BW photographs for 40 years, I am  
> > quite
> > confident of that.
>

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington" 
<roy@h...> wrote:
>
> 
Roy-

Thanks for the response.  I used "paper white" in the 2.3.0 profile 
and found this useful.  I can't use it in the 2.3.2 profile (without 
also "simulating" the ink).  But are you saying that there is no 
grayscale information going to the soft proof (other than paper white 
in 2.3.0)?

Thank you,
Walt


> I have to agree that I don't particularly like either of the 
Simulate check boxes.
> These are both Photoshop features not ICC features.  There is no 
info about
> what PS is really doing with these.  The only thing that the ICC 
profile has in it
> that I think is relevant is the media white-point and black-point.  
These are
> just the values read for the paper white and the darkest ink patch.
> 
> The major difference between 2.3.0 and 2.3.2 is that the former 
used a single
> gray transfer tag so soft-proof really didn't show anything.  The 
new one uses
> the color lookup tables which have two curves -- a gray one for 
printing and a
> color one for the softproofing.
> 
> Roy
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl Schofield 
<scho@m...> 
> wrote:
> >
> > Do you mean simulate black ink instead of "ink color" in the  
> > softproof dialog (CS2) ?  Also, I agree that checking simulate 
paper  
> > color and/or black ink when softproofing  is not at all 
realistic  
> > (even when looking away to avoid brain tricks).  Just doesn't cut 
it  
> > for me.  Like putting a fog layer over the image.  I get 
excellent  
> > screen/print matches with neither of these options checked, using 
a  
> > calibrated Apple LCD monitor.
> > 
> > Carl
> > 
> > 
> > > I have discovered that the soft proofing is different in 2.3.2 
than it
> > > was in 2.3.0, as follows:
> > >
> > > In 2.3.0, paper color can be selected but this does not 
automatically
> > > select ink color.  This is a very accurate soft proof.  It is 
not
> > > possible with any combination of soft proof settings to select 
ink
> > > color.
> > >
> > > In 2.3.1, when paper color is selected, ink color is 
automatically
> > > selected.  There is no way to select paper color without ink 
color.
> > >
> > > With Epson canned color profiles, soft proofing works as with 
2.3.0.
> > >
> > > Regardless of what has been said, the ink-color-checked soft 
proof  
> > > does
> > > not provide an accurate soft proof of the print output with 
regard to
> > > darker tones.  Having looked at BW photographs for 40 years, I 
am  

> > > quite
> > > confident of that.
> >
>

> From: wwodets <odets@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Mon, 24 Oct 2005 22:31:12 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: ICC Soft Proofing -- The issue . . .
> 
> Steve -
> 
> Thanks.
> 
> Yes, I too noted that the Epson profiles do not allow simulate ink
> color.
> 
> My display calibration is good (i1) at 65K/2.2.

FYI this is likely a good part of why you like to use Simulate Paper White.
D65 is a very bright white.  I have my display set to D50.  Initially it
looks like a very dull display but you get over that very quickly.  With a
D50 display there is only a "slight" difference to paper white for good
matte papers with Simulate Paper White (paper substrates are better at the
white end than ink on paper is at the black end).  (Photo papers are a whole
different story because they are really blue.)  Try it for a while and see
what you think.  Some commentators will say the white point of a calibrated
display is not so important because your eye adjusts to white differences
very quickly but seen as this is the sensitive end of the equation for you I
suspect that shifting your monitor white point to coincide more closely with
the ICC spec (you illuminated the profiling target with D50 lighting) and
your print viewing conditions may help.  Give it a whirl.

The gamma you calibrate to is much less important because colour management
takes care of any differences and you are better off simply using the
display's native gamma so that the display itself has less hoops to jump
through.

>I am viewing the 
> monitor in a semi-darkened room, which makes the blacks more intense,
> and they are quite good I think.  My print viewing is at 5K (measures
> actually 4950) and 450-500 lux.
> 
> I am going to try working up a new print from scratch with the soft
> proof and simulate ink color and see what I come up with for a
> print.  It will be too contrasty I think, an effort to comensate for
> the "unrealistically" weak monitor blacks shown in soft proof.  I'll
> see.
> 
> Having just looked at the Epson canned profile for VFA (which allows
> paper white without ink black), I might just use that!  I need the
> paper white for a good soft proof and I don't need the paper black.
> 
> I am surprised that a profile itself dictates these PS settings--
> sounds like differences in the format rather than just the correction
> curve.  But I don't know what I'm talking about on this score.

I don't think it's the profile dictating but simply whether the info in the
profile is all there or not or all there in a manner which allows it - if
that makes sense.

I have used a viewing booth for colour work with a friend of mine who is a
pro fashion photographer (I don't have a viewing booth at home).  We had
matches that were bang on when Simulate Paper Color and Ink Black were
checked (without them checked the black was way off for obvious reasons).
So I think the model works well.  As to whether it is USEFUL is a whole
different story, especially if you are an artist/hobbyist and you don't have
full control over the lighting conditions in which your work is viewed.  I'd
like to improve the lighting conditions of my work area (and hence I intend
to get some solux bulbs) but as soon as I move my prints away from D50
lighting I know the soft proof match is no longer valid.

> From: Roy Harrington <roy@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 00:18:52 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> 
> I have to agree that I don't particularly like either of the Simulate check
> boxes.
> These are both Photoshop features not ICC features.  There is no info about
> what PS is really doing with these.  The only thing that the ICC profile has
> in it
> that I think is relevant is the media white-point and black-point.  These are
> just the values read for the paper white and the darkest ink patch.
> 
> The major difference between 2.3.0 and 2.3.2 is that the former used a single
> gray transfer tag so soft-proof really didn't show anything.  The new one uses
> the color lookup tables which have two curves -- a gray one for printing and a
> color one for the softproofing.
> 
> Roy

Steve,

Well, according to Bruce Fraser 
(http://www.creativepro.com/story/feature/15310.html)
"When both Paper White and Ink Black are unchecked, Photoshop uses Relative 
Colorimetric rendering with Black Point Compensation to go from the 
simulation to your monitor. What that means in English is that the paper 
white is mapped to your monitor's white, and the printer's black is mapped 
to your monitor's black. If you're printing to a bright glossy stock, this 
view is probably the most accurate. But if you're printing to a matte paper 
it may give you an overly optimistic view."

"The Ink Black checkbox turns off black point compensation in the rendering 
from the simulation to your monitor, and attempts to show you the actual 
black that will appear in print. If you're simulating printing to a glossy 
paper, you'll probably just see a very slight lightening of the shadows. If 
you're simulating printing to watercolor paper, newsprint, or an uncoated 
stock that produces relatively weak blacks, the shadows will likely lighten 
a lot when you check Ink Black. This setting is useful for fine-tuning 
shadow detail, particularly on stocks that produce weaker blacks."

"The Paper White checkbox makes Photoshop do an Absolute Colorimetric 
rendering from the simulation space to your monitor. It attempts to show you 
the influence of the paper color and also the true black (when you check 
Paper White, it automatically checks, and dims, Ink Black). But to do that, 
it has to dim all the colors -- to change the color of white, it has to 
reduce the values in one or more of the channels that it sends to the 
monitor, because the only way to change the color from RGB 255,255, 255 
(your monitor's white) is to turn something down. As a result, your first 
reaction when checking paper white may be that your image just died before 
your eyes. I've become accustomed to looking away from the monitor when I 
check Paper White so that I don't see the change happen. This simple trick 
makes it a lot easier to accept the paper color displayed on the monitor as 
a true white."



Bob Frost.

----- Original Message ----- 

From: "Steve Kale" <stevekale@...>



This is the same with the GM i1 Photo profiles.  If you select Simulate
Paper Color then Simulate Ink Black is automatically and irreversibly
checked (except by unchecking Simulate Paper Color).  One can Simulate Ink
Black without simulating paper color but not the other way around.
Interestingly, the Epson provided profiles (Mac 4800 driver) don't allow you
to Simulate Ink Black at all.

We're not sure what Adobe does when you check these settings, what it looks
for etc. I know this is one area where Roy would like to know more - for
obvious reasons.

Roy,

See my previous post to Steve; Bruce Fraser seems to know what PS is doing.

Bob Frost.

----- Original Message ----- 
From: "Roy Harrington" <roy@...>



I have to agree that I don't particularly like either of the Simulate check 
boxes.
These are both Photoshop features not ICC features.  There is no info about
what PS is really doing with these.

Yes but I think the thing we don't understand is why some profiles allow
these operations and others don't. That is we need, ideally, to figure out
what PS grabs from the ICC profile.

> From: Bob Frost <bob@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 16:23:45 +0100
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> Steve,
> 
> Well, according to Bruce Fraser
> (http://www.creativepro.com/story/feature/15310.html)
> "When both Paper White and Ink Black are unchecked, Photoshop uses Relative
> Colorimetric rendering with Black Point Compensation to go from the
> simulation to your monitor. What that means in English is that the paper
> white is mapped to your monitor's white, and the printer's black is mapped
> to your monitor's black. If you're printing to a bright glossy stock, this
> view is probably the most accurate. But if you're printing to a matte paper
> it may give you an overly optimistic view."
> 
> "The Ink Black checkbox turns off black point compensation in the rendering
> from the simulation to your monitor, and attempts to show you the actual
> black that will appear in print. If you're simulating printing to a glossy
> paper, you'll probably just see a very slight lightening of the shadows. If
> you're simulating printing to watercolor paper, newsprint, or an uncoated
> stock that produces relatively weak blacks, the shadows will likely lighten
> a lot when you check Ink Black. This setting is useful for fine-tuning
> shadow detail, particularly on stocks that produce weaker blacks."
> 
> "The Paper White checkbox makes Photoshop do an Absolute Colorimetric
> rendering from the simulation space to your monitor. It attempts to show you
> the influence of the paper color and also the true black (when you check
> Paper White, it automatically checks, and dims, Ink Black). But to do that,
> it has to dim all the colors -- to change the color of white, it has to
> reduce the values in one or more of the channels that it sends to the
> monitor, because the only way to change the color from RGB 255,255, 255
> (your monitor's white) is to turn something down. As a result, your first
> reaction when checking paper white may be that your image just died before
> your eyes. I've become accustomed to looking away from the monitor when I
> check Paper White so that I don't see the change happen. This simple trick
> makes it a lot easier to accept the paper color displayed on the monitor as
> a true white."
> 
> 
> 
> Bob Frost.
>

I don't see any profiles that allow simulate paper color without simulate
black ink unless they don't have a bkpt tag, so its moot.  Am I missing
something?
An interesting example is SPR2400 ProofingSemimatte.icm which does not have
a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.

Does that suggest Epson knows most people don't want to simulate paper black
while softproofing?  If any profile were to be used for softproofing, I
would think ProofingSemimatte would be it.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Tuesday, October 25, 2005 11:34 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .


Yes but I think the thing we don't understand is why some profiles allow
these operations and others don't. That is we need, ideally, to figure out
what PS grabs from the ICC profile.





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

I have not taken an extensive look but my GM i1 profiles allow checking ink
black without checking paper white but not the other way around.  The point
Walt was making is that he would like to check paper white without checking
ink black.  Such combination is not possible with the GM profiles and I am
not sure it makes sense anyway.  The GM profiles don't have bkpt tags.  None
of the Epson 4800 profiles I looked at allow you to check ink black at all.
None have a bkpt tag.  When I was asking Phil Green about this tag he said
words to the effect that it was "not a mandatory tag in the spec, you can
put it in but you need an application that can make use of it."  We're just
a bunch of colour blind guys who don't know squat about colour, wandering
around in the dark and grey.  Perhaps this is illustrative of the ground we
need to cover, who knows...

> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 15:12:21 -0400
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> I don't see any profiles that allow simulate paper color without simulate
> black ink unless they don't have a bkpt tag, so its moot.  Am I missing
> something?
> An interesting example is SPR2400 ProofingSemimatte.icm which does not have
> a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.
> 
> Does that suggest Epson knows most people don't want to simulate paper black
> while softproofing?  If any profile were to be used for softproofing, I
> would think ProofingSemimatte would be it.
> 
> Best regards,
> John Moody

I suspect that this how it works -- that they are linked by the PS code.
If anyone finds a counter-example I like to see it.  I don't think any of this
is documented so examples tend to be the best info.

I think there may be CM systems that don't handle BPC the way PS does.
This may be why Epson provides profiles with it builtin.

Roy


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody" 
<moodymz3@y...> wrote:

>
> I don't see any profiles that allow simulate paper color without simulate
> black ink unless they don't have a bkpt tag, so its moot.  Am I missing
> something?
> An interesting example is SPR2400 ProofingSemimatte.icm which does not have
> a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.
> 
> Does that suggest Epson knows most people don't want to simulate paper black
> while softproofing?  If any profile were to be used for softproofing, I
> would think ProofingSemimatte would be it.
> 
> Best regards,
> John Moody
> 
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
> Sent: Tuesday, October 25, 2005 11:34 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> 
> Yes but I think the thing we don't understand is why some profiles allow
> these operations and others don't. That is we need, ideally, to figure out
> what PS grabs from the ICC profile.
>

The 4800 profiles I am looking at, all have blackpoints, and you can pick,
simulate-black-ink in PS.  Epson even lists the L* values for convenience.

Epson StylusR Pro 4800
L* Values
Profile Name White / Black Driver Setting Used
SP4800 EM MK 2880.icc 96 / 17 Enhanced Matte at 2880 dpi
SP4800 EVFA MK 2880.icc 98 / 16 Velvet Fine Art Paper at 2880 dpi
SP4800 PAWRC MK 1440.icc 96 / 21 Watercolor Paper - Radiant White at 1440
dpi
SP4800 PAWRC PK 1440.icc 96 / 27 Watercolor Paper - Radiant White at 1440
dpi
SP4800 PGPP250 PK 2880.icc 94 / 3 Premium Glossy Photo Paper (250) at 2880
dpi
SP4800 PLPP PK 2880.icc 94 / 4 Premium Luster Photo Paper at 2880 dpi
SP4800 PLPP250 PK 2880.icc 96 / 5 Premium Luster Photo Paper (250) at 2880
dpi
SP4800 PSMPP250 PK 2880.icc 96 / 7 Premium Semimatte Photo Paper (250) at
2880
SP4800 USFAP MK 2880.icc 98 / 18 UltraSmooth Fine Art Paper at 2880 dpi

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Tuesday, October 25, 2005 4:33 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .

I have not taken an extensive look but my GM i1 profiles allow checking ink
black without checking paper white but not the other way around.  The point
Walt was making is that he would like to check paper white without checking
ink black.  Such combination is not possible with the GM profiles and I am
not sure it makes sense anyway.  The GM profiles don't have bkpt tags.  None
of the Epson 4800 profiles I looked at allow you to check ink black at all.
None have a bkpt tag.  When I was asking Phil Green about this tag he said
words to the effect that it was "not a mandatory tag in the spec, you can
put it in but you need an application that can make use of it."  We're just
a bunch of colour blind guys who don't know squat about colour, wandering
around in the dark and grey.  Perhaps this is illustrative of the ground we
need to cover, who knows...


> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 15:12:21 -0400
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .
>
> I don't see any profiles that allow simulate paper color without simulate
> black ink unless they don't have a bkpt tag, so its moot.  Am I missing
> something?
> An interesting example is SPR2400 ProofingSemimatte.icm which does not
have
> a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.
>
> Does that suggest Epson knows most people don't want to simulate paper
black
> while softproofing?  If any profile were to be used for softproofing, I
> would think ProofingSemimatte would be it.
>
> Best regards,
> John Moody






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

LOL, the Epson Quick Reference Sheet has a typo on the PK watercolor
profile, L* black is 22, not 27.  :-)

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of John Moody
Sent: Tuesday, October 25, 2005 5:04 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .

The 4800 profiles I am looking at, all have blackpoints, and you can pick,
simulate-black-ink in PS.  Epson even lists the L* values for convenience.

Epson StylusR Pro 4800
L* Values
Profile Name White / Black Driver Setting Used
SP4800 EM MK 2880.icc 96 / 17 Enhanced Matte at 2880 dpi
SP4800 EVFA MK 2880.icc 98 / 16 Velvet Fine Art Paper at 2880 dpi
SP4800 PAWRC MK 1440.icc 96 / 21 Watercolor Paper - Radiant White at 1440
dpi
SP4800 PAWRC PK 1440.icc 96 / 27 Watercolor Paper - Radiant White at 1440
dpi
SP4800 PGPP250 PK 2880.icc 94 / 3 Premium Glossy Photo Paper (250) at 2880
dpi
SP4800 PLPP PK 2880.icc 94 / 4 Premium Luster Photo Paper at 2880 dpi
SP4800 PLPP250 PK 2880.icc 96 / 5 Premium Luster Photo Paper (250) at 2880
dpi
SP4800 PSMPP250 PK 2880.icc 96 / 7 Premium Semimatte Photo Paper (250) at
2880
SP4800 USFAP MK 2880.icc 98 / 18 UltraSmooth Fine Art Paper at 2880 dpi

Best regards,
John Moody




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

Interesting.  I am looking at the profiles installed by the Mac driver on
the UK site.  In actual fact it doesn't install the profiles in a
conventional fashion, ie place them in /Library/Colorsync/Profiles.  The
only way to view them is to go to /Library/Printers/Epson/SPro4800.plugin
and Show Package Contents - they are then under Resources. Are you on a Mac
or PC?  If Mac is yours like this? Epson works in mysterious ways I
guess...But then the bkpt tag can't be the trigger because none of my i1
profiles have the bkpt tag.

> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 17:10:58 -0400
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> LOL, the Epson Quick Reference Sheet has a typo on the PK watercolor
> profile, L* black is 22, not 27.  :-)
> 
> Best regards,
> John Moody
> 
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of John Moody
> Sent: Tuesday, October 25, 2005 5:04 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> The 4800 profiles I am looking at, all have blackpoints, and you can pick,
> simulate-black-ink in PS.  Epson even lists the L* values for convenience.
> 
> Epson StylusR Pro 4800
> L* Values
> Profile Name White / Black Driver Setting Used
> SP4800 EM MK 2880.icc 96 / 17 Enhanced Matte at 2880 dpi
> SP4800 EVFA MK 2880.icc 98 / 16 Velvet Fine Art Paper at 2880 dpi
> SP4800 PAWRC MK 1440.icc 96 / 21 Watercolor Paper - Radiant White at 1440
> dpi
> SP4800 PAWRC PK 1440.icc 96 / 27 Watercolor Paper - Radiant White at 1440
> dpi
> SP4800 PGPP250 PK 2880.icc 94 / 3 Premium Glossy Photo Paper (250) at 2880
> dpi
> SP4800 PLPP PK 2880.icc 94 / 4 Premium Luster Photo Paper at 2880 dpi
> SP4800 PLPP250 PK 2880.icc 96 / 5 Premium Luster Photo Paper (250) at 2880
> dpi
> SP4800 PSMPP250 PK 2880.icc 96 / 7 Premium Semimatte Photo Paper (250) at
> 2880
> SP4800 USFAP MK 2880.icc 98 / 18 UltraSmooth Fine Art Paper at 2880 dpi
> 
> Best regards,
> John Moody

I'm on PC.
BTW, my i1match profiles do not have bkpt either, but you can select
simulate-black-ink in PS, and it does lighten the black.  Looking at i1match
profiles in ColorThink you can see the obvious non-zero black point value in
the 3D gamut view; that must be where PS gets the black point value, at
least for i1match profiles.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Tuesday, October 25, 2005 5:32 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .

Interesting.  I am looking at the profiles installed by the Mac driver on
the UK site.  In actual fact it doesn't install the profiles in a
conventional fashion, ie place them in /Library/Colorsync/Profiles.  The
only way to view them is to go to /Library/Printers/Epson/SPro4800.plugin
and Show Package Contents - they are then under Resources. Are you on a Mac
or PC?  If Mac is yours like this? Epson works in mysterious ways I
guess...But then the bkpt tag can't be the trigger because none of my i1
profiles have the bkpt tag.





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

I see no consistancy here between the ability to preview paper white
and/or ink black, and the presence of wtpt and/or bkpt tags in the
profiles.
For one odd example, I have 2 profiles here, one will preview paper
white but not ink black, the other will do the reverse, ink black but
not paper white. They both have wtpt tags, no bkpt tags.
This preview ability could also be derived from the LUTs I would
think. But why some and not others?
Another unknown. Along with how to make great art.
T
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington"
<roy@h...> wrote:
>
> 
> I suspect that this how it works -- that they are linked by the PS code.
> If anyone finds a counter-example I like to see it.  I don't think
any of this
> is documented so examples tend to be the best info.
> 
> I think there may be CM systems that don't handle BPC the way PS does.
> This may be why Epson provides profiles with it builtin.
> 
> Roy
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody" 
> <moodymz3@y...> wrote:
> >
> > I don't see any profiles that allow simulate paper color without
simulate
> > black ink unless they don't have a bkpt tag, so its moot.  Am I
missing
> > something?
> > An interesting example is SPR2400 ProofingSemimatte.icm which does
not have
> > a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.
> > 
> > Does that suggest Epson knows most people don't want to simulate
paper black
> > while softproofing?  If any profile were to be used for
softproofing, I
> > would think ProofingSemimatte would be it.
> > 
> > Best regards,
> > John Moody
> > 
> > -----Original Message-----
> > From: DigitalBlackandWhiteThePrint@yahoogroups.com
> > [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
Steve Kale
> > Sent: Tuesday, October 25, 2005 11:34 AM
> > To: DigitalBlackandWhiteThePrint@yahoogroups.com
> > Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> > 
> > 
> > Yes but I think the thing we don't understand is why some profiles
allow
> > these operations and others don't. That is we need, ideally, to
figure out

> > what PS grabs from the ICC profile.
> >
>

> From: Tyler Boley <tyler@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 22:05:58 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: ICC Soft Proofing -- The issue . . .
> 
> I see no consistancy here between the ability to preview paper white
> and/or ink black, and the presence of wtpt and/or bkpt tags in the
> profiles.
> For one odd example, I have 2 profiles here, one will preview paper
> white but not ink black, the other will do the reverse, ink black but
> not paper white. They both have wtpt tags, no bkpt tags.
> This preview ability could also be derived from the LUTs

I agree.  The wtpt tag is mandatory while the bkpt tag is not.  It's either
in the B2Ax tag(s) or the "gamt" tags.  I am not familiar with the latter.
We should probably ask the question over at Adobe's PS forums or perhaps the
Colorsync list.  We here are just guessing.

>I would
> think. But why some and not others?
> Another unknown. Along with how to make great art.
> T

Ok so we're looking at completely different profiles for an entirely
different driver - well at least I am not going blind.

> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 25 Oct 2005 18:05:20 -0400
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> I'm on PC.

I don't think the tags are what trigger the checkbox options.  Its the
data in the LUTs.  If black in the LUT is pure black then you don't get an
Ink Black box -- i.e. blacks are already matched in-to-out, and no BPC needed.
When the black in the LUT is lighter, BPC is default on but Ink Black will turn it
off.   For white I think its slightly different.  White in the LUT is supposed to be
"illuminant white" but the wtpt tag (required) shows the media white.  If these
are different the checkbox Paper White is available.  But this conversion will also
turn off the BPC thus showing Ink Black -IF- it's in the LUT.  Kind of roundabout 
dependencies but the icc spec leaves quite a bit up to the profile designer,
the CMS and the display code (soft-proofing).

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Tyler Boley" <tyler@t...> 
wrote:

>
> I see no consistancy here between the ability to preview paper white
> and/or ink black, and the presence of wtpt and/or bkpt tags in the
> profiles.
> For one odd example, I have 2 profiles here, one will preview paper
> white but not ink black, the other will do the reverse, ink black but
> not paper white. They both have wtpt tags, no bkpt tags.
> This preview ability could also be derived from the LUTs I would
> think. But why some and not others?
> Another unknown. Along with how to make great art.
> T
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington"
> <roy@h...> wrote:
> >
> > 
> > I suspect that this how it works -- that they are linked by the PS code.
> > If anyone finds a counter-example I like to see it.  I don't think
> any of this
> > is documented so examples tend to be the best info.
> > 
> > I think there may be CM systems that don't handle BPC the way PS does.
> > This may be why Epson provides profiles with it builtin.
> > 
> > Roy
> > 
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody" 
> > <moodymz3@y...> wrote:
> > >
> > > I don't see any profiles that allow simulate paper color without
> simulate
> > > black ink unless they don't have a bkpt tag, so its moot.  Am I
> missing
> > > something?
> > > An interesting example is SPR2400 ProofingSemimatte.icm which does
> not have
> > > a bkpt tag, yet SPR2400 PremSmgls PhotoRPM.icc does.
> > > 
> > > Does that suggest Epson knows most people don't want to simulate
> paper black
> > > while softproofing?  If any profile were to be used for
> softproofing, I
> > > would think ProofingSemimatte would be it.
> > > 
> > > Best regards,
> > > John Moody
> > > 
> > > -----Original Message-----
> > > From: DigitalBlackandWhiteThePrint@yahoogroups.com
> > > [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
> Steve Kale
> > > Sent: Tuesday, October 25, 2005 11:34 AM
> > > To: DigitalBlackandWhiteThePrint@yahoogroups.com
> > > Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> > > 
> > > 
> > > Yes but I think the thing we don't understand is why some profiles
> allow
> > > these operations and others don't. That is we need, ideally, to
> figure out
> > > what PS grabs from the ICC profile.
> > >
> >
>

Steve,

> The point Walt was making is that he would like to check paper white
> without checking ink black.

But he can't because Absolute Colorimetric rendering (as in Simulate Paper 
White) doesn't use BPC. That only comes with Relative Colorimetric rendering 
(with Simulate Paper White off), where you can turn it on or off.

Bob Frost.

----- Original Message ----- 
From: "Steve Kale" <stevekale@...>

I don't have the answer.  Personally I do not know why one would want to
check paper colour without ink black anyway but then the man has the right
to ask and I do believe he mentioned it was possible on earlier iterations.
Personally, I am very happy with things the way they are and this is all
just intellectual curiosity.  I posted a question pertaining to this on the
Adobe Colour Management Forum and I'll let people know of any feedback I
receive.

FYI the QTR ICC profiles only have one rendering intent - perceptual.  There
are no A2B2/B2A2 or A2B1/B2A1 tags.  In addition, Roy seems to only use the
Out Curve part of the A2B0/B2A0 tags which would make sense as an easier
application because we are just applying transfer curves.  I have never seen
a colour profile use this portion of the tag.  I fully admit I only
scratched the surface when it came to understanding the application of these
tags.

> From: Bob Frost <bob@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 26 Oct 2005 10:32:52 +0100
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> Steve,
> 
>> The point Walt was making is that he would like to check paper white
>> without checking ink black.
> 
> But he can't because Absolute Colorimetric rendering (as in Simulate Paper
> White) doesn't use BPC. That only comes with Relative Colorimetric rendering
> (with Simulate Paper White off), where you can turn it on or off.
> 
> Bob Frost.
>

BTW I think the below may be fine for the PCS to Device (B2A0) tag since we
are just applying a simple transfer function to a single channel,ie to
luminance only, and BPC can be built into this transform.  I wonder, though,
if it creates complications on the soft proof leg, Device to PCS (A2B0),
because it will be this tag (I assume) that PS coordinates with most for
soft proofing. 

> From: Steve Kale <stevekale@...>

> In addition, Roy seems to only use the
> Out Curve part of the A2B0/B2A0 tags which would make sense as an easier
> application because we are just applying transfer curves.  I have never seen
> a colour profile use this portion of the tag.

Only the OutCurve is used since both directions only have one input channel.
You can have 3 sets of curves for the different intents but the "0" curve will
be used for all if the others don't exist.   The softproof is based on the A2B0
curve and although potentially there could be 3 different soft-proof curves
there's no way to select which one is used for the reverse direction, nor can
you select BPC on/off for the reverse.  So you must decide where the black is
mapped before making the profile.

Roy


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:

>
> BTW I think the below may be fine for the PCS to Device (B2A0) tag since we
> are just applying a simple transfer function to a single channel,ie to
> luminance only, and BPC can be built into this transform.  I wonder, though,
> if it creates complications on the soft proof leg, Device to PCS (A2B0),
> because it will be this tag (I assume) that PS coordinates with most for
> soft proofing. 
> 
> 
> > From: Steve Kale <stevekale@b...>
> 
> > In addition, Roy seems to only use the
> > Out Curve part of the A2B0/B2A0 tags which would make sense as an easier
> > application because we are just applying transfer curves.  I have never seen
> > a colour profile use this portion of the tag.
>

Hi Roy

You know this stuff much better than I do but as I understand it there are 4
parts to any A2B0 (or other like tag):

1. The identity matrix - a given for Lab PCS
2. The 1D input table (curve)
3. The multidimensional CLUT
4. The 1D output table (curve)

You've used 4. to generate the transform rather than 3. If PS normally goes
looking into the CLUT for bpc generation etc then what will it find?
Colorsync portrays the CLUT contents as perfect lab.

Thinking about it a little more, I guess PS would most likely pass data
through the entire transform 1-4 but I am just speculating.  If that's the
case, for a single channel situation it doesn't matter where in 2-4 the info
is kept.  But I am puzzled though by a comment you made some time ago
(probably offline) that PS bpc did not work with the new profiles and so you
had to build it in.  It suggests PS is not finding the data it needs.  (Of
course it all works in the end because you have done the bpc for PS.)


> From: Roy Harrington <roy@...>

> 
> 
> Only the OutCurve is used since both directions only have one input channel.
> You can have 3 sets of curves for the different intents but the "0" curve will
> be used for all if the others don't exist.

Yes. My question is whether you use the output table or the CLUT.

>The softproof is based on the
> A2B0 curve and although potentially
>there could be 3 different soft-proof curves
> there's no way to select which one is used for the reverse direction, nor can
> you select BPC on/off for the reverse.  So you must decide where the black is
> mapped before making the profile.


I'm not sure I follow you here.  Presumably PS would normally look to the
correct intent tag as per Bob Frost's earlier post.  That is there wouldn't
be "3 different soft proof curves", per se, but rather PS would look to the
relevant intent depending on the settings checked in the soft proof.  (I
don't see any other profiles using 2 or 4 above.)  We just have one intent
so each time it looks it comes to the same place.  I guess I need to think
this through a bit more. Hmmm.

Steve

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:
>
> Hi Roy
> 
> You know this stuff much better than I do but as I understand it there are 4
> parts to any A2B0 (or other like tag):
> 
> 1. The identity matrix - a given for Lab PCS
> 2. The 1D input table (curve)
> 3. The multidimensional CLUT
> 4. The 1D output table (curve)
> 
> You've used 4. to generate the transform rather than 3. If PS normally goes
> looking into the CLUT for bpc generation etc then what will it find?
> Colorsync portrays the CLUT contents as perfect lab.
> 
> Thinking about it a little more, I guess PS would most likely pass data
> through the entire transform 1-4 but I am just speculating.  If that's the
> case, for a single channel situation it doesn't matter where in 2-4 the info
> is kept.  

Yes, this is the idea.  With multidimensional input and output there's a lot of
space saving by having multiple steps.  The CLUT is the one that takes up all 
the room.  Typically 25 points are used giving a 3in-3out size of 25*25*25*3*2 
bytes.  With only 25 points per dimension, linear interpolation is done for all
the midpoints.  The InCurves and OutCurves can afford all 256 values and these 
make the linear interpolation in the CLUT as accurate as possible.

So bottom line is the whole tag can be thought of as one transfer function that
is usually n-inputs to m-outputs but if our case only one input is used.  
The B2A0 goes from the file's L* value to the QTR driver's K value.  The A2B0
goes from a QTR driver K value to the L,a,b values of the soft proof.   
Using just the OutCurves fits the needs the best.  All the other pieces are identity
functions (pass the data through unmodified).


But I am puzzled though by a comment you made some time ago
> (probably offline) that PS bpc did not work with the new profiles and so you
> had to build it in.  It suggests PS is not finding the data it needs.  (Of
> course it all works in the end because you have done the bpc for PS.)

The difference is that in the TRC method there's only one curve which is setup
most like a A2B0 curve.  The CMS takes the one curve and calculates the two
directions so both directions come from the same data.  BPC could be used to
fix a curve that didn't go through (0,0).

With the A2B and B2A tags you specify exactly you want to happen in each
direction.  In B2A0 L=0 must naturally map to dMax or K=100.  In fact you
have to map all the L's into reasonable K's and this is the BPC-like scaling.
In the A2B0 K=100 maps into say L=16, and if you have Ink Black on it displays
as L=16 but the default for softproofs is for PS to do BPC and map it to L=0.
So PS is actually doing the BPC for the proof.

My comment in the past about "doing the BPC myself" was for the B2A0 tag.

> 
> 
> > From: Roy Harrington <roy@h...>
> 
> > 
> > 
> > Only the OutCurve is used since both directions only have one input channel.
> > You can have 3 sets of curves for the different intents but the "0" curve will
> > be used for all if the others don't exist.
> 
> Yes. My question is whether you use the output table or the CLUT.
> 
> >The softproof is based on the
> > A2B0 curve and although potentially
> >there could be 3 different soft-proof curves
> > there's no way to select which one is used for the reverse direction, nor can
> > you select BPC on/off for the reverse.  So you must decide where the black is
> > mapped before making the profile.
> 
> 
> I'm not sure I follow you here.  Presumably PS would normally look to the
> correct intent tag as per Bob Frost's earlier post.  That is there wouldn't
> be "3 different soft proof curves", per se, but rather PS would look to the
> relevant intent depending on the settings checked in the soft proof.

I'm pretty sure the Intent you are selecting in the soft-proof dialog is the
intent to be used in the forward direction not the reverse.  According to Bob's
post it's the PaperWhite which selects the different reverse intent, and that's 
for Absolute which doesn't have its own tag.

Roy

> (I don't see any other profiles using 2 or 4 above.)  We just have one intent
> so each time it looks it comes to the same place.  I guess I need to think
> this through a bit more. Hmmm.
> 
> Steve
>

> From: Roy Harrington <roy@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 26 Oct 2005 21:32:18 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing -- The issue . . .
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> 
> wrote:
>> 
>> Hi Roy
>> 
>> You know this stuff much better than I do but as I understand it there are 4
>> parts to any A2B0 (or other like tag):
>> 
>> 1. The identity matrix - a given for Lab PCS
>> 2. The 1D input table (curve)
>> 3. The multidimensional CLUT
>> 4. The 1D output table (curve)
>> 
>> You've used 4. to generate the transform rather than 3. If PS normally goes
>> looking into the CLUT for bpc generation etc then what will it find?
>> Colorsync portrays the CLUT contents as perfect lab.
>> 
>> Thinking about it a little more, I guess PS would most likely pass data
>> through the entire transform 1-4 but I am just speculating.  If that's the
>> case, for a single channel situation it doesn't matter where in 2-4 the info
>> is kept.  
> 
> Yes, this is the idea.  With multidimensional input and output there's a lot
> of
> space saving by having multiple steps.  The CLUT is the one that takes up all
> the room.  Typically 25 points are used giving a 3in-3out size of 25*25*25*3*2
> bytes.  With only 25 points per dimension, linear interpolation is done for
> all
> the midpoints.  


I didn't realise there was a limit on the number of observations.

>The InCurves and OutCurves can afford all 256 values and these
> make the linear interpolation in the CLUT as accurate as possible.
> 
> So bottom line is the whole tag can be thought of as one transfer function
> that
> is usually n-inputs to m-outputs but if our case only one input is used.
> The B2A0 goes from the file's L* value to the QTR driver's K value.  The A2B0
> goes from a QTR driver K value to the L,a,b values of the soft proof.
> Using just the OutCurves fits the needs the best.  All the other pieces are
> identity
> functions (pass the data through unmodified).
> 
> 
>> But I am puzzled though by a comment you made some time ago
>> (probably offline) that PS bpc did not work with the new profiles and so you
>> had to build it in.  It suggests PS is not finding the data it needs.  (Of
>> course it all works in the end because you have done the bpc for PS.)
> 
> The difference is that in the TRC method there's only one curve which is setup
> most like a A2B0 curve.  The CMS takes the one curve and calculates the two
> directions so both directions come from the same data.  BPC could be used to
> fix a curve that didn't go through (0,0).

Yes.

> 
> With the A2B and B2A tags you specify exactly you want to happen in each
> direction.  In B2A0 L=0 must naturally map to dMax or K=100.  In fact you
> have to map all the L's into reasonable K's and this is the BPC-like scaling.

> My comment in the past about "doing the BPC myself" was for the B2A0 tag.

Yes I knew it was in relation to B2A0.   If this is the case, it makes me
wonder why there is a BPC in the print pane.  If all profiles map from file
pixel value 0 to dMax with black point scaling then there would be no need
for it.

> In the A2B0 K=100 maps into say L=16, and if you have Ink Black on it displays
> as L=16 but the default for softproofs is for PS to do BPC and map it to L=0.
> So PS is actually doing the BPC for the proof.

The PC guys have one advantage over the Mac guys re looking at profiles.
ICC Profile Inspector seems to allow people to look directly at the 16 bit
values stored in the CLUT.  I would love to look into the B2A0/1 CLUTs for a
GM i1 generated profile as a means of comparison...

Re your mention of 25 points.  I assume the "For Input Values Of:" depiction
we see in Colorsync Utility which has a range of 0-24 is linked to this.  I
have never fully understood how to read this.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:
>
> Re your mention of 25 points.  I assume the "For Input Values Of:" depiction
> we see in Colorsync Utility which has a range of 0-24 is linked to this.  I
> have never fully understood how to read this.
>

The format isn't limited to 25 points.  That's just what the profile maker
decided was a good compromise because of profile size.  I think the spec
says 2 to 4096 points.  But consider 256 points:  on a 3 color profile that
256 * 256 * 256 points = 16 million pts.  Each point is 3 values * 2 bytes.
Then times 3 intents in each direction.   That would be upwards of 600 megabytes
for a profile.  Clearly not practical.  Even 25 points makes a big profle -- .5 MB.
With my gray profiles using just the OutCurves, I calculate and store all 256
values but the total size is just a couple K bytes.  With the In/Out curves
you get a lot more precision for a lot less space.

What you are looking at in ColorSync Utility is one slice of the 3D clut.  You
fix 2 of the dimension values and it shows the graph of the other dimension.
The numbers are all normalized 0 to 1, so when you see 0-24, 24 represents 1.
All the others are fractions.  The LUT is very much like PS Curves with evenly
spaced points.  You just have to imagine that in 3 dimensions.  The In and Out
curves are easier to understand since they are 1 dimensional.

There is a OS X program that shows the innards of the icc file but requires using
the command line interface.  Let me know if you want to pursue that.

Roy

I finally clarified various issues relating to Simulate Black Ink in Epson's
ICC profiles yesterday.  The profiles installed when one installs an Epson
driver do not have the ability to simulate black ink.  For each intent,
including relative colormetric, Epson has built some form of black point
compensation into their profiles so that the black point extends to perfect
black.  Thus when you do a soft proof, PS sees perfect black and greys out
simulate ink black.

The Epson USA website provides another set of profiles for download - in
addition to those installed by the driver installation.  These profiles have
been made not by Epson (and are not supported by Epson) but by X-Rite.
Clearly it is a way for X-Rite to be seen by many Epson users.  These
profiles behave in the "conventional" manner with respect to Simulate Black
Ink.

I can only think that the reason why Epson has built black point
compensation directly into their profiles is because either (a) they don't
want to highlight how bad the black point can be, (2) they don't believe
that simulating black ink is useful, (3) they don't like the way Adobe PS
does black point compensation and prefer their own algorithm, or (4) some
mix of these.  It's also interesting to note the difference in a soft proof
using a GM i1 profile between perceptual (which has built-in BPC) and
relative colormetric which does not.  In a B&W world, one would generally
expect these two to be the same.  The only explanation that I can see is
that GM uses a different BPC algorithm to Adobe PS.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale 
<stevekale@b...> wrote:
>
> 
> I finally clarified various issues relating to Simulate Black Ink 
in Epson's
> ICC profiles yesterday.  The profiles installed when one installs 
an Epson
> driver do not have the ability to simulate black ink.  For each 
intent,
> including relative colormetric, Epson has built some form of black 
point
> compensation into their profiles so that the black point extends to 
perfect
> black.  Thus when you do a soft proof, PS sees perfect black and 
greys out
> simulate ink black.
> 
> The Epson USA website provides another set of profiles for 
download - in
> addition to those installed by the driver installation.  These 
profiles have
> been made not by Epson (and are not supported by Epson) but by X-
Rite.
> Clearly it is a way for X-Rite to be seen by many Epson users.  
These
> profiles behave in the "conventional" manner with respect to 
Simulate Black
> Ink.
> 
> I can only think that the reason why Epson has built black point
> compensation directly into their profiles is because either (a) 
they don't
> want to highlight how bad the black point can be, 

I think this is most likely, it would keep a lot of people from 
calling asking why the image on their monitor looks so bad when they 
softproof with the default profiles. Also keeps people from knowing 
exactly what the dmax is for a given paper without actually printing 
on that paper.

Also in my chat with Level 2 support in the UK, they were still very proud
of the performance of MK ink.  I did not get the sense that they thought it
uncompetitive.  They also raised the subject of black only printing in
relation to requests to fix the 2100 driver.  In short, they weren't going
to spend the money to make any alterations when they were aware that the K3
Adv B&W solution was just around the corner.  In essence, they said black
only was dead from here on.

> From: Greg <dfaprinting@...>

> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
>> 
>> 
>> I finally clarified various issues relating to Simulate Black Ink
> in Epson's
>> ICC profiles yesterday.  The profiles installed when one installs
> an Epson
>> driver do not have the ability to simulate black ink.  For each
> intent,
>> including relative colormetric, Epson has built some form of black
> point
>> compensation into their profiles so that the black point extends to
> perfect
>> black.  Thus when you do a soft proof, PS sees perfect black and
> greys out
>> simulate ink black.
>> 
>> The Epson USA website provides another set of profiles for
> download - in
>> addition to those installed by the driver installation.  These
> profiles have
>> been made not by Epson (and are not supported by Epson) but by X-
> Rite.
>> Clearly it is a way for X-Rite to be seen by many Epson users.
> These
>> profiles behave in the "conventional" manner with respect to
> Simulate Black
>> Ink.
>> 
>> I can only think that the reason why Epson has built black point
>> compensation directly into their profiles is because either (a)
> they don't
>> want to highlight how bad the black point can be,
> 
> I think this is most likely, it would keep a lot of people from
> calling asking why the image on their monitor looks so bad when they
> softproof with the default profiles. Also keeps people from knowing
> exactly what the dmax is for a given paper without actually printing
> on that paper.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
<stevekale@b...> wrote:
...
> I can only think that the reason why Epson has built black point
> compensation directly into their profiles is because either (a) they
don't
> want to highlight how bad the black point can be, (2) they don't believe
> that simulating black ink is useful, (3) they don't like the way
Adobe PS
> does black point compensation and prefer their own algorithm, or (4)
some
> mix of these.

I think it has more to do with the fact that few, if any, average
Epson users would ever need shadow information from a file clipped
below the ink black point, and therefore a normal colormetric
conversion is nearly useless and would probably lead to more tech
support calls. Believe it or not a great many decisions in this
industry are driven by their potential consequences on tech support.
I can think of a few reasons to need a straight colormetric conversion
once in a great while, but I can't imagine many others needing it for
normal printing. Under most circimstances with a tonally full file, it
will clip.

>  It's also interesting to note the difference in a soft proof
> using a GM i1 profile between perceptual (which has built-in BPC) and
> relative colormetric which does not.  In a B&W world, one would
generally
> expect these two to be the same.  The only explanation that I can see is
> that GM uses a different BPC algorithm to Adobe PS.

I don't think they've ever been the same nor should be. BPC is not
"built in" to perceptual rendering. Something similar to it is an
natural consequence of remapping/compression to the destination gamut.
RelCol with BPC, in theory and in my experience, is supposed to leave
much of the scale alone, and simply begin to compress at some point in
the shadows eventually reaching an in gamut black point at the end.
You will see middle gray shift much more in a perceptual conversion
than a RelCol with BPC conversion. If I recall from months ago,
maintaining the middle gray value in your conversions was desirable to
you, therefore perceptual may not be useful.
You will also see, strangely, with CMYK profiles, a DIFFERENT black
value (CMYK ink combo) resulting from the two different kinds of
conversions, with some profiles.
Of course, since profile builders can make perceptual tables however
they like, and BPC is not an icc standard, but an Adobe implemetation,
many of these issues are not cast in stone.
Tyler

Hi Tyler

> 
> I don't think they've ever been the same nor should be. BPC is not
> "built in" to perceptual rendering.

The Perceptual intent requires that black points be mapped.  So "black point
compensation", in the general sense (as opposed to Adobe's specific
algorithm), is required.  There are, however, no specifications as to how
this must be achieved.  In fact, as you note below, there are no rules as to
how the Perceptual intent is to be managed.  It is entirely up to the
profile maker (or software provider) - so-called "secret sauce".

> Something similar to it is an
> natural consequence of remapping/compression to the destination gamut.
> RelCol with BPC, in theory and in my experience, is supposed to leave
> much of the scale alone, and simply begin to compress at some point in
> the shadows eventually reaching an in gamut black point at the end.
> You will see middle gray shift much more in a perceptual conversion
> than a RelCol with BPC conversion.

We are really talking about the same thing.  A straight Relcol has no black
point mapping so Adobe introduced BPC to plug the gap.  Perceptual requires
black point mapping but how you do it is not specified.  In a colour world
there are very real differences between these two intents because of how
non-greyscale out-of-gamut colours are managed (ie shrink the entire gamut
to fit, perceptual, or render the next best in-gamut colour, relcol).  In a
greyscale world, though, there aren't any out-of-gamut colours remaining
once you have mapped the black and white points.  So if you were approaching
the issue purely from a greyscale world perspective then you'd be facing an
identical technical issue.

The bit I don't get is this.  The greyscale axis is a straight line up
through the middle of a gamut plot.  If I had to create a transform that
mapped both black and white points be it either in one go like perceptual or
in two steps like relcol with bpc then I would expect the same transformed
greyscale in the end.  Obviously this is not the case.  The fact that Epson
prefers its own "black point mapped relcol" transform could suggest,
perhaps, that they are not happy with Adobe BPC.

At the end of the day, the ICC spec has dictated how white points should be
mapped but not yet dealt with mapping black point (it's not part of relcol
and perceptual methods are not prescribed).  So it's up to the software
provider to think of an algorithm that makes the most sense. I guess I
wouldn't have thought that there would be too many
scientifically-supportable alternatives but maybe there are...

Steve







>If I recall from months ago,
> maintaining the middle gray value in your conversions was desirable to
> you, therefore perceptual may not be useful.

I would say my thinking on this has changed in that I prefer a more
perceptually pleasing change in tone from black to white.  What I have found
though thus far is that the QTR Create ICC approach slots that mid grey
right about where it is in the file workspace.  For colour work, I much
prefer relcol over perceptual.

> You will also see, strangely, with CMYK profiles, a DIFFERENT black
> value (CMYK ink combo) resulting from the two different kinds of
> conversions, with some profiles.
> Of course, since profile builders can make perceptual tables however
> they like, and BPC is not an icc standard, but an Adobe implemetation,
> many of these issues are not cast in stone.
> Tyler
>

Sorry I meant to add that I agree with your comments below

> From: Tyler Boley <tyler@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 01 Nov 2005 17:55:04 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
> ...
>> I can only think that the reason why Epson has built black point
>> compensation directly into their profiles is because either (a) they
> don't
>> want to highlight how bad the black point can be, (2) they don't believe
>> that simulating black ink is useful, (3) they don't like the way
> Adobe PS
>> does black point compensation and prefer their own algorithm, or (4)
> some
>> mix of these.
> 
> I think it has more to do with the fact that few, if any, average
> Epson users would ever need shadow information from a file clipped
> below the ink black point, and therefore a normal colormetric
> conversion is nearly useless and would probably lead to more tech
> support calls. Believe it or not a great many decisions in this
> industry are driven by their potential consequences on tech support.
> I can think of a few reasons to need a straight colormetric conversion
> once in a great while, but I can't imagine many others needing it for
> normal printing. Under most circimstances with a tonally full file, it
> will clip.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
<stevekale@b...> wrote:
...
> We are really talking about the same thing.  A straight Relcol has
no black
> point mapping so Adobe introduced BPC to plug the gap.  Perceptual
requires
> black point mapping but how you do it is not specified.  In a colour
world
> there are very real differences between these two intents because of how
> non-greyscale out-of-gamut colours are managed (ie shrink the entire
gamut
> to fit, perceptual, or render the next best in-gamut colour,
relcol).  In a
> greyscale world, though, there aren't any out-of-gamut colours remaining
> once you have mapped the black and white points.  So if you were
approaching
> the issue purely from a greyscale world perspective then you'd be
facing an
> identical technical issue.

I don't think so, and that was the point of my first reply.
The whole point of RelCol is to map in gamut colors as closely as
possible to the LAB equivalent in the destination space. In gray,
everything is IN GAMUT except the extremes, white point is taken care
of, then everything down to media/ink dmax is in gamut.
Therefore in the majority of the scale there is little compression,
and Adobe then came up with some math to compress shadows
porportionally more, to bring back shadow detail.

In fact, this is why one would select that rendering over perceptual
if apropriate. It's how most of the profiles I have here work, from
various creators.
Put up a gray step wedge, do a perceptual vrs relcol conversion- in
perceptual everything lightens, in RelCol it does not, but the blacks
clip. Now with Relcol hit BPC, mid tones lighten little, but shadow
detail returns.

That is how I would expect it to perform, based on the definitions of
the intents and BPC, and that is indeed how it seems to perform here.
Of course it's not 100% consistant because of the lack of relevant
standards, but mostly.
Tyler

I hear you but if you read up on the literature there is little detail on
why there's a difference.  In terms of goal definition they discuss the same
thing with respect to black point.  Adobe BPC, for example, which is
applicable to RelCol/BPC, scales the entire luminance with the matrix we
have discussed in other threads - it's not confined to an adjustment in just
the darker regions (at least according to my understanding of their white
paper).   Roy could perhaps comment here.

GM put out an interesting pdf called "Cook Book: Soft Proofing Settings,
Adobe Software".  It's not quite on point because it is specifically
discussing soft proofing and I need to read the whole thing again but here's
a couple of quotes:

[pg11] "Perceptual scales the white point and black point of the color space
you are converting from to the full lightness range of the color space you
are converting into.....

"Relative Colormetric scales the white point of the color space you are
converting from relatively to the maximum lightness of the color space you
are converting into, but scales the black point of the color space you are
converting from 1:1 absolutely to the shadow end of the lightness range in
the color space you are converting into."

So far so good - recol clips the blacks, perceptual doesn't....

[earlier on pg11] "Black point compensation is as of the time of writing a
conversion specific to Adobe application software, and not yet implemented
in all Adobe software. Black point compensation is an optional modification
of relative colormetric conversions, but because it is currently applied to
all steps from source space to destination space, it also affects the black
point of the proof.

In principle limited to scaling the L channel, bpc slides the black point of
the space you are converting from up or down to match the black point of the
color space you are converting into which avoids clipping of shadow details.
Because this may expand the simulated lightness range in the destination
space, you should disable it for soft proofing and print-proofing."

Not sure why they felt the need for the cautious "in principle" and I'm not
sure about the tale end of each of those paragraphs...

[pg25] "black point compensation, a modification of Relative Colormetric
conversion, makes the black point relative just like the white point,
matching the source black L end point to the simulation black L end point.
This conversion is an alternative to the Perceptual default, if you uncheck
Black Point Compensation before proofing."

All very confusing but the drift I get from this is that relcol with bpc
scales the white point to match and (in the L channel only) "slides" the
black point to match.  I have trouble seeing the difference between this and
the scaling of both white and black point done for perceptual.

Probably a question for the guys over on the Colorsync list.

Cheers

Steve

> From: Tyler Boley <tyler@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 01 Nov 2005 21:22:55 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
> ...
>> We are really talking about the same thing.  A straight Relcol has
> no black
>> point mapping so Adobe introduced BPC to plug the gap.  Perceptual
> requires
>> black point mapping but how you do it is not specified.  In a colour
> world
>> there are very real differences between these two intents because of how
>> non-greyscale out-of-gamut colours are managed (ie shrink the entire
> gamut
>> to fit, perceptual, or render the next best in-gamut colour,
> relcol).  In a
>> greyscale world, though, there aren't any out-of-gamut colours remaining
>> once you have mapped the black and white points.  So if you were
> approaching
>> the issue purely from a greyscale world perspective then you'd be
> facing an
>> identical technical issue.
> 
> I don't think so, and that was the point of my first reply.
> The whole point of RelCol is to map in gamut colors as closely as
> possible to the LAB equivalent in the destination space. In gray,
> everything is IN GAMUT except the extremes, white point is taken care
> of, then everything down to media/ink dmax is in gamut.
> Therefore in the majority of the scale there is little compression,
> and Adobe then came up with some math to compress shadows
> porportionally more, to bring back shadow detail.
> 
> In fact, this is why one would select that rendering over perceptual
> if apropriate. It's how most of the profiles I have here work, from
> various creators.
> Put up a gray step wedge, do a perceptual vrs relcol conversion- in
> perceptual everything lightens, in RelCol it does not, but the blacks
> clip. Now with Relcol hit BPC, mid tones lighten little, but shadow
> detail returns.
> 
> That is how I would expect it to perform, based on the definitions of
> the intents and BPC, and that is indeed how it seems to perform here.
> Of course it's not 100% consistant because of the lack of relevant
> standards, but mostly.
> Tyler
>

Steve, once again I have to cry uncle. I just can't follow the twists
and turns of your posts and how they relate as an answer to mine. We
have somewhat of a disconnect on the written page.
We pretty much know all of the below, certainly the cook book's been
around a very long time. I just don't know what you're getting at. All
I'm saying is that the two intents of interest, Perceptual and RelCol
w/BPC, behave differently here. The difference may not be entirely
consistant, but generally. Additionally, that difference makes some
sense to me, sorry.
The exact math is of no interest to me, I can't do anything about it.
These are the options given us, they both work, they are both useful.
I am happy, prints are beautiful, life is occassionally good.
By the way, I did not say RelCol/BPC was "confined" to the nether regions.
Good luck with this-
Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
<stevekale@b...> wrote:
>
> I hear you but if you read up on the literature there is little
detail on
> why there's a difference.  In terms of goal definition they discuss
the same
> thing with respect to black point.  Adobe BPC, for example, which is
> applicable to RelCol/BPC, scales the entire luminance with the matrix we
> have discussed in other threads - it's not confined to an adjustment
in just
> the darker regions (at least according to my understanding of their
white
> paper).   Roy could perhaps comment here.
> 
> GM put out an interesting pdf called "Cook Book: Soft Proofing Settings,
> Adobe Software".  It's not quite on point because it is specifically
> discussing soft proofing and I need to read the whole thing again
but here's
> a couple of quotes:
> 
> [pg11] "Perceptual scales the white point and black point of the
color space
> you are converting from to the full lightness range of the color
space you
> are converting into.....
> 
> "Relative Colormetric scales the white point of the color space you are
> converting from relatively to the maximum lightness of the color
space you
> are converting into, but scales the black point of the color space
you are
> converting from 1:1 absolutely to the shadow end of the lightness
range in
> the color space you are converting into."
> 
> So far so good - recol clips the blacks, perceptual doesn't....
> 
> [earlier on pg11] "Black point compensation is as of the time of
writing a
> conversion specific to Adobe application software, and not yet
implemented
> in all Adobe software. Black point compensation is an optional
modification
> of relative colormetric conversions, but because it is currently
applied to
> all steps from source space to destination space, it also affects
the black
> point of the proof.
> 
> In principle limited to scaling the L channel, bpc slides the black
point of
> the space you are converting from up or down to match the black
point of the
> color space you are converting into which avoids clipping of shadow
details.
> Because this may expand the simulated lightness range in the destination
> space, you should disable it for soft proofing and print-proofing."
> 
> Not sure why they felt the need for the cautious "in principle" and
I'm not
> sure about the tale end of each of those paragraphs...
> 
> [pg25] "black point compensation, a modification of Relative Colormetric
> conversion, makes the black point relative just like the white point,
> matching the source black L end point to the simulation black L end
point.
> This conversion is an alternative to the Perceptual default, if you
uncheck
> Black Point Compensation before proofing."
> 
> All very confusing but the drift I get from this is that relcol with bpc
> scales the white point to match and (in the L channel only) "slides" the
> black point to match.  I have trouble seeing the difference between
this and
> the scaling of both white and black point done for perceptual.
> 
> Probably a question for the guys over on the Colorsync list.
> 
> Cheers
> 
> Steve
> 
> 
> > From: Tyler Boley <tyler@t...>
> > Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > Date: Tue, 01 Nov 2005 21:22:55 -0000
> > To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > Subject: Re: [Digital BW] ICC Soft Proofing
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> > <stevekale@b...> wrote:
> > ...
> >> We are really talking about the same thing.  A straight Relcol has
> > no black
> >> point mapping so Adobe introduced BPC to plug the gap.  Perceptual
> > requires
> >> black point mapping but how you do it is not specified.  In a colour
> > world
> >> there are very real differences between these two intents because
of how
> >> non-greyscale out-of-gamut colours are managed (ie shrink the entire
> > gamut
> >> to fit, perceptual, or render the next best in-gamut colour,
> > relcol).  In a
> >> greyscale world, though, there aren't any out-of-gamut colours
remaining

> >> once you have mapped the black and white points.  So if you were
> > approaching
> >> the issue purely from a greyscale world perspective then you'd be
> > facing an
> >> identical technical issue.
> > 
> > I don't think so, and that was the point of my first reply.
> > The whole point of RelCol is to map in gamut colors as closely as
> > possible to the LAB equivalent in the destination space. In gray,
> > everything is IN GAMUT except the extremes, white point is taken care
> > of, then everything down to media/ink dmax is in gamut.
> > Therefore in the majority of the scale there is little compression,
> > and Adobe then came up with some math to compress shadows
> > porportionally more, to bring back shadow detail.
> > 
> > In fact, this is why one would select that rendering over perceptual
> > if apropriate. It's how most of the profiles I have here work, from
> > various creators.
> > Put up a gray step wedge, do a perceptual vrs relcol conversion- in
> > perceptual everything lightens, in RelCol it does not, but the blacks
> > clip. Now with Relcol hit BPC, mid tones lighten little, but shadow
> > detail returns.
> > 
> > That is how I would expect it to perform, based on the definitions of
> > the intents and BPC, and that is indeed how it seems to perform here.
> > Of course it's not 100% consistant because of the lack of relevant
> > standards, but mostly.
> > Tyler
> >
>

It's simple: in every description I've read of the two (perceptual vs
relcol+bpc) including that which I quoted below there is no stated
difference with regard to the greyscale axis.  You claim, by virtue of
observation only, that there is a difference with regard to the greyscale
axis but can't adequately explain why.  You dismissed my suggestion that
possibly a profile builder would want, when given the freedom the perceptual
intent gives him/her to do things any way he wants, to tackle the issue of
mapping black point in a manner differently to Adobe's BPC algorithm simply
because you "don't think they've ever been the same nor should be".

I'd like to understand how and why.

The reason for this is QTR Create ICC currently deploys the relcol+bpc
approach (as best we understand it).  If a greyscale perceptual-intent
profile builder were, given freedom, to prefer a different approach (and,
yes, with different maths) then I'd like to understand the differences.  The
latter may well provide a better initial basis for a transform of B&W
content from file to print.

Steve

> From: Tyler Boley <tyler@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 02 Nov 2005 00:59:33 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC Soft Proofing
> 
> Steve, once again I have to cry uncle. I just can't follow the twists
> and turns of your posts and how they relate as an answer to mine. We
> have somewhat of a disconnect on the written page.
> We pretty much know all of the below, certainly the cook book's been
> around a very long time. I just don't know what you're getting at. All
> I'm saying is that the two intents of interest, Perceptual and RelCol
> w/BPC, behave differently here. The difference may not be entirely
> consistant, but generally. Additionally, that difference makes some
> sense to me, sorry.
> The exact math is of no interest to me, I can't do anything about it.
> These are the options given us, they both work, they are both useful.
> I am happy, prints are beautiful, life is occassionally good.
> By the way, I did not say RelCol/BPC was "confined" to the nether regions.
> Good luck with this-
> Tyler
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
>> 
>> I hear you but if you read up on the literature there is little
> detail on
>> why there's a difference.  In terms of goal definition they discuss
> the same
>> thing with respect to black point.  Adobe BPC, for example, which is
>> applicable to RelCol/BPC, scales the entire luminance with the matrix we
>> have discussed in other threads - it's not confined to an adjustment
> in just
>> the darker regions (at least according to my understanding of their
> white
>> paper).   Roy could perhaps comment here.
>> 
>> GM put out an interesting pdf called "Cook Book: Soft Proofing Settings,
>> Adobe Software".  It's not quite on point because it is specifically
>> discussing soft proofing and I need to read the whole thing again
> but here's
>> a couple of quotes:
>> 
>> [pg11] "Perceptual scales the white point and black point of the
> color space
>> you are converting from to the full lightness range of the color
> space you
>> are converting into.....
>> 
>> "Relative Colormetric scales the white point of the color space you are
>> converting from relatively to the maximum lightness of the color
> space you
>> are converting into, but scales the black point of the color space
> you are
>> converting from 1:1 absolutely to the shadow end of the lightness
> range in
>> the color space you are converting into."
>> 
>> So far so good - recol clips the blacks, perceptual doesn't....
>> 
>> [earlier on pg11] "Black point compensation is as of the time of
> writing a
>> conversion specific to Adobe application software, and not yet
> implemented
>> in all Adobe software. Black point compensation is an optional
> modification
>> of relative colormetric conversions, but because it is currently
> applied to
>> all steps from source space to destination space, it also affects
> the black
>> point of the proof.
>> 
>> In principle limited to scaling the L channel, bpc slides the black
> point of
>> the space you are converting from up or down to match the black
> point of the
>> color space you are converting into which avoids clipping of shadow
> details.
>> Because this may expand the simulated lightness range in the destination
>> space, you should disable it for soft proofing and print-proofing."
>> 
>> Not sure why they felt the need for the cautious "in principle" and
> I'm not
>> sure about the tale end of each of those paragraphs...
>> 
>> [pg25] "black point compensation, a modification of Relative Colormetric
>> conversion, makes the black point relative just like the white point,
>> matching the source black L end point to the simulation black L end
> point.
>> This conversion is an alternative to the Perceptual default, if you
> uncheck
>> Black Point Compensation before proofing."
>> 
>> All very confusing but the drift I get from this is that relcol with bpc
>> scales the white point to match and (in the L channel only) "slides" the
>> black point to match.  I have trouble seeing the difference between
> this and
>> the scaling of both white and black point done for perceptual.
>> 
>> Probably a question for the guys over on the Colorsync list.
>> 
>> Cheers
>> 
>> Steve
>

uncle

uncleuncleuncle

you are supremely adequate

me...
...mmm ... not so much

ah screw it, here we go...

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
<stevekale@b...> wrote:
>
> It's simple: in every description I've read of the two (perceptual vs
> relcol+bpc) including that which I quoted below there is no stated
> difference with regard to the greyscale axis.  You claim, by virtue of
> observation only, that there is a difference with regard to the
greyscale
> axis but can't adequately explain why.

Observation works quite well thanks. I think that's one reason most of
us accept that the world is not flat. The explanation seemed, and
remains, adequate to me. At this point that's enough.

>  You dismissed my suggestion that
> possibly a profile builder would want, when given the freedom the
perceptual
> intent gives him/her to do things any way he wants, to tackle the
issue of
> mapping black point in a manner differently to Adobe's BPC algorithm
simply
> because you "don't think they've ever been the same nor should be".

I did not intend to dismiss any suggestion of yours. However the
statement remains true to me at least. I made some attempt to explain
why, perhaps inadequately to you, adequately to me. Also, this is a
bit out of context. The statement was made as a response to this (as
long as we're quoting each other)-
" It's also interesting to note the difference in a soft proof
 using a GM i1 profile between perceptual (which has built-in BPC) and
 relative colormetric which does not. In a B&W world, one would
generally
 expect these two to be the same."

There was no dismissal on my part about what a profile builder might
wish to do. You noted the different behavior between the two
conversions, and claimed they should not be different. I replied that
they are different, and why it made sense to me that they remain so.
Color management remains somewhat mysterious to many, I certainly
respect your dogged attempts for more technical clarity.
However, when I see a statement that in my experience is in error or
may confuse matters, I jump in. Again-
Perceptual conversions vrs Relative Colormetric w/ BPC conversions
behave differently here the vast majority of the time, it's definite,
not refutable. In addition, that differing behavior makes some sense
to me, and I won't attempt again to explain why.

I would have hoped that the above observations would have helped your
general inquiry into this whole issue.
Again, for some reason, possibly the way we both write, we seem to
descend into something that feels a bit "tit for tat". It's not my
intention, and it's uncomfortable.
So- uncle
Tyler

And not my intention either.

I agree that the two intents (or rather: perceptual vs relcol+bpc) quite
often lead to different results.  Yet I have not had anyone or anything
explain adequately to me why this is so for the B&W subset (other than a
"it's just so" type of answer which I find unsatisfactory and, obviously,
react against).  Each tackles the issue of black point mapping but obviously
(as empirical observation suggests) in different ways.  More to the point,
the perceptual intent is the only one that allows freedom to the profiling
package manufacturer and so it is interesting to note that when allowed they
choose a path that doesn't replicate relcol+bpc.  Presumably they do this
with good reason - if the bpc method for mapping black point did such a
great job I suspect a similar algorithm would be deployed in the perceptual
intent (unless of course it got in the way of a non-greyscale axis goal).

One possible explanation for the nature of the Epson profiles is that they
are unhappy with the combined implementation of relcol+bpc and so they wrote
their own black-point-mapped relcol intent.  (There are, of course, other
possible explanations.)

If we can learn more about what the colour guys know about black point
mapping or "handling the gray axis in the calculation of the perceptual
rendering intent" there exists a possibility to improve/expand QTR Create
ICC beyond the current relcol+bpc which is labelled "perceptual".

My goal is to try to push that along if I can.

Steve

PS:   PM 5 has a setting to allow the user to "define handling the gray axis
in the calculation of the perceptual rendering intent".  Unfortunately I
don't have PM 5 and can't see from the online user manual what the options
are. If anyone has info on this it would be appreciated.

> From: Tyler Boley <tyler@...>

> Again, for some reason, possibly the way we both write, we seem to
> descend into something that feels a bit "tit for tat". It's not my
> intention, and it's uncomfortable.
> So- uncle
> Tyler

Oh, and the whole "uncle" thing is just 747 to me.  Doesn't translate to
Kiwi very well.

:-)

>On 02/11/2005 23:23:03, Steve Kale (stevekale@...) wrote:
 >PS:   PM 5 has a setting to allow the user to "define handling the gray
axis
>in the calculation of the perceptual rendering intent".  Unfortunately I
>don't have PM 5 and can't see from the online user manual what the options
>are. If anyone has info on this it would be appreciated.

From the PM5 Help File: 
*******************************************
"Perceptual Rendering Intent Option

Daily work shows that different aspects are frequently required for ideal
implementation of a gray axis. ProfileMaker therefore provides two methods
for defining the gray axis. These definitions affect only the Perceptual
Rendering Intent. 

With Paper-Colored Gray, the substrate color of the scanner/camera testchart
or the paper color of the print run affects the entire color space. This may
shift the gray axis of the image. Colors in the image may end up with a cast
although they are in fact neutral. This means that even a medium gray still
has a yellow cast on a yellow paper. In printing, this corresponds to the
use of the same printing plates for papers with different colors (paper
white).

Note: From the technical point of view, this corresponds to relative
colorimetry with shadow compensation.

With the Neutral Gray option, the substrate color or paper color only
affects lighter areas. In the other color areas, the colors and gray axis of
the image are preserved to the best possible extent, and are not influenced
by the paper white.

Note: This corresponds to relative colorimetry in highlight areas and
absolute colorimetry with shadow compensation in the remaining colors.

Note: The default and recommended setting is Neutral Gray.

For example, if B/W and color images are positioned next to each other in
reproduction, the Paper Gray Axis option should be selected to achieve the
same impression in the neutral tones both in the B/W images and in the color
images. Conversely, if an ad is produced that must be reproduced with
identical results in offset printing and in gravure (with the exception of
highlights that are allowed to differ on account of the different papers
used), the Neutral Gray option should be used when generating the offset and
gravure profiles.

Note: The Perceptual Rendering Intent calculation options Paper Gray or
Neutral Gray don't affect the proofing process. In the proofing process the
Relative Colorimetric or Absolute Colorimetric Rendering Intent is used."
********************************************


TonyR

Steve, from the manual: Paper-Colored Gray and Neutral Gray

Daily work shows that different aspects are frequently required for ideal
implementation of a gray axis. ProfileMaker therefore provides two methods
for defining the gray axis. These definitions affect only the Perceptual
Rendering Intent.

With Paper-Colored Gray, the substrate color of the scanner/camera testchart
or the paper color of the print run affects the entire color space. This may
shift the gray axis of the image. Colors in the image may end up with a cast
although they are in fact neutral. This means that even a medium gray still
has a yellow cast on a yellow paper. In printing, this corresponds to the
use of the same printing plates for papers with different colors (paper
white).

Note: From the technical point of view, this corresponds to relative
colorimetry with shadow compensation.

With the Neutral Gray option, the substrate color or paper color only
affects lighter areas. In the other color areas, the colors and gray axis of
the image are preserved to the best possible extent, and are not influenced
by the paper white.

Note: This corresponds to relative colorimetry in highlight areas and
absolute colorimetry with shadow compensation in the remaining colors.

Note: The default and recommended setting is Neutral Gray.


For example, if B/W and color images are positioned next to each other in
reproduction, the Paper Gray Axis option should be selected to achieve the
same impression in the neutral tones both in the B/W images and in the color
images. Conversely, if an ad is produced that must be reproduced with
identical results in offset printing and in gravure (with the exception of
highlights that are allowed to differ on account of the different papers
used), the Neutral Gray option should be used when generating the offset and
gravure profiles.

Note: The Perceptual Rendering Intent calculation options Paper Gray or
Neutral Gray don't affect the proofing process. In the proofing process the
Relative Colorimetric or Absolute Colorimetric Rendering Intent is used.

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Wednesday, November 02, 2005 6:23 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing

Steve

PS:   PM 5 has a setting to allow the user to "define handling the gray axis
in the calculation of the perceptual rendering intent".  Unfortunately I
don't have PM 5 and can't see from the online user manual what the options
are. If anyone has info on this it would be appreciated.




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

John and Toy

Thanks for that. So it's a paper colour correction issue rather than a
luminance option, per se.  That makes things easier.  It's not like there
are multiple choices for luminance axis management.

It's interesting that the default is to correct for paper colour, ie to
introduce colour ink - I would have thought this would contribute to
metamerism in the greyscale case.  Presumably the Neutral Gray default is
what's used for EyeOne Match.

Thanks

Steve

Steve,
The default and recommended setting is Neutral Gray.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Thursday, November 03, 2005 6:03 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing

John and Toy

Thanks for that. So it's a paper colour correction issue rather than a
luminance option, per se.  That makes things easier.  It's not like there
are multiple choices for luminance axis management.

It's interesting that the default is to correct for paper colour, ie to
introduce colour ink - I would have thought this would contribute to
metamerism in the greyscale case.  Presumably the Neutral Gray default is
what's used for EyeOne Match.

Thanks

Steve




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

Yes which I understand from your post (and Tony's) corrects the paper colour
as much as it can.  Obviously it can't correct the highlights but it does
correct the mid to three-quarter tones.  The Paper-Coloured Grey option
would likely have less potential for colour ink induced metamerism.

> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 3 Nov 2005 06:34:36 -0500
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing
> 
> Steve,
> The default and recommended setting is Neutral Gray.
> 
> Best regards,
> John Moody
>

Steve,
Oh yes, I see what you mean if the paper is warm.  For cold papers, it might
go the other way.  It's a good thing we have better ways of making BW
prints...

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Thursday, November 03, 2005 7:09 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] ICC Soft Proofing

Yes which I understand from your post (and Tony's) corrects the paper colour
as much as it can.  Obviously it can't correct the highlights but it does
correct the mid to three-quarter tones.  The Paper-Coloured Grey option
would likely have less potential for colour ink induced metamerism.


> From: John Moody <moodymz3@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 3 Nov 2005 06:34:36 -0500
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC Soft Proofing
>
> Steve,
> The default and recommended setting is Neutral Gray.
>
> Best regards,
> John Moody
>





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