Digital BW, The Print

I think the best way to view all this is that there are multiple layers, each of
which have specific roles and definitions.  Then there are conversions from
one level to the next -- color management and print or screen drivers.

(1) File level
 At the file level the pixel numbers have "profiles" that tell what the pixels mean.
This is the function the gray spaces and the color spaces.  Whether you are in
GG 2.2 or Dot Gain 20 or Gray Lab determines what the grayscale numbers mean. 
Similarly AdobeRGB or sRGB or ProPhotoRGB tell what the RGB numbers mean.
These are all "idealized" profile spaces, they are not tied to a particular devices.


(2) Actual input values to a driver -- print or screen, gray or RGB
In general these tend to be hidden, you don't necessarily know these values.
These are tied to a device but are basically a high-level description of what
you want.

(3) The lowest level is the nitty-gritty of what the device needs -- number of
drops of each ink, or screen control lines etc. 

Device drivers are the most visible piece of code.  They convert from (2) to (3).
The regular Epson driver expects RGB input and converts to K,C,M,Y,LC,LM,LK
output in a way that is optimized for color printing. QTR expects a gray input
and converts to K,C,M,Y,LC,LM,LK output in a way that is optimized for B&W
printing.  The new Epson ABW mode is like QTR -- gray input and optimized
for B&W printing.  The Black Only printing available in some drivers is also similar.

The Epson drivers are all "black boxes" -- you can't see or control the actual
conversions.  QTR on the other hand is very open, so if you want you can see and
manipulate all the internal conversions, making is possible to do-your-own.
QTR curves or QTR profiles are the guts of the conversions.

---------------

ICC Color Management is the connection between (1) and (2). It's a wonderful
concept but since it's been introduced over time there are various places that
it can be done.  Just in PS you can Convert explicitly or use the Print Space when
printing.  The OS's support it some places and drivers sometimes support it, too.
This is the source of the "double profiling" problems -- you really don't want to
convert from (1) to (2) multiple times.  For PS I think by far the most popular is
in the Print Space but if you are not printing with PS you may have to convert
explicitly.

For the color world Color Management is pretty much a given everywhere.  
Every device has profiles built for it.  These profiles describe the correspondence
between the level (2) values and universal color values -- Lab or XYZ. 
The ICC definitions are include B&W, RGB and CMYK but in general all the well-
known profiling packages concentrate on color rather than B&W.  B&W is
somewhat simplified compared to color but it has it's own unique characteristics.

QTR-Create-ICC is a new tool to expand full color management to a true B&W
workflow.  The current version creates profiles for the printing side.  A soft-
proofing version is coming soon.  The concept is identical to making color
profiles -- print a target without CM, measure it, create the .icc file.  Then you
just print using that ICC profile.   For now I'm just bundling the QTR-Create-ICC
with QTR Printing but it is truly a completely separate function.  It is usable with
any B&W workflow -- i.e. any driver that takes a grayscale input can benefit.
QTR is one such workflow, but Epson ABW or BO are perfect candidates. 
Lack of grayscale ICC's are the weakest point of the ABW currently (IMO).

---

A potential source of confusion is that the Linearizing and ICC Profiling procedures
are very similar.  In both you print the same target and read it the same way.
I think the way to think of it is that the Linearizing is part of the QTR driver. 
It linearizes from dMin to dMax of the specific paper and ink so the driver can 
give consistent results.  This is the (2) to (3) conversion from above.

The ICC profiling is for the upper level (1) to (2) conversion by the CM.  Here
you are characterizing the driver in a profile that the CM can use for conversions.
There are also a couple of other things that are useful.  You can ICC profile with
any settings of the QTR driver -- for instance QTR profiles are linearized
individually but you can ICC profile any Tone Blend or Ink Limit Adj.  If you have
a favorite setup you can specifically ICC profile that -- when the soft-proofing
is done this will be more obviously useful.  And of course the fact that the
profiling can be used with other drivers is a big difference.

Roy




--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "joshhackney" 
<joshhackney@g...> wrote:
> 
> Thanks everyone for your input.  Your comments have been very helpful, and I'll be 
re-
> thinking my workflow over the next few weeks.  
> 
> I'm looking forward to getting the i1 in house and to start using it with QTR create 
ICC.  
> Following Steve's "color managed" approach is most intuitive to me, since it is so 
similar to 
> my color workflow.  Steve, just to clarify one point.  When you use your QTR create 
ICC 
> profiles with PS set to "Let PS determine colors", are you printing through QTR, or 
are you 
> bypassing QTR and going straight to the print driver?  If you use the icc profile you 
create 
> with QTR create ICC AND print through QTR, aren't you converting your file twice?  
(I'm not 
> sure if "converting" in the previous sentence was the proper word, but I think you 
get the 
> idea).  At first I thought you were bypassing QTR, but judging from your latest 
comments 
> about hue, it seems that you are in fact using the ICC profile and QTR.
> 
> Thanks a million to everyone who has contributed to my continuing education.  I 
hope to 
> be able to give back to the community someday.
> 
> Best.
> 
> Josh
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale 
<stevekale@b...> 
> wrote:
> > Well it depends.  (Personally I don't use the Channel Mixer method as I find
> > it restricting.  I prefer to use the Split Channels method and consequently
> > I get a greyscale file.  I use GG 2.2 because I can bounce into Adobe RGB
> > for PK Sharpener and back to greyscale without vexing the file too much.  I
> > do not store this output sharpened file and so my B&W image is stored in
> > greyscale with its lower storage and work size.  I do not print using Paul's
> > curves.)  It depends on your workflow (as Clayton said in an earlier mail).
> > If the rest of your workflow is expecting a gamma of 2.2 and you use a
> > colour space with a different gamma then you will run into problems if you
> > are not colour managing your output to the printer (ie selecting a printer
> > profile with Let Photoshop Determine Colors at the printing stage): in this
> > case your selection of workspace matters.  I believe Paul does all his
> > curves work for an Adobe RGB space and hence working in ProPhoto is not a
> > good idea if you want to use his methodology.  Clayton uses DotGain 20%
> > because he too doesn't colour manage his output and he finds that this
> > workspace matches his print space the best.  My bet is that a workspace of
> > GG2.2 or Adobe RGB is the underlying assumption in the non colour managed
> > Epson Adv B&W workflow.
> > 
> > BUT the core point of this conversation has been that a No Color
> > Management/Same as Source workflow is now rather dated (perhaps with the key
> > exception of Paul's workflow - see below *).  Anyone printing to a
> > linearised greyscale, such as those using QTR, IJC/OPM and Epson Adv B&W, or
> > those printing to a non-linearised greyscale, such as those using Black Only
> > printing, would do well to avail themselves of the little but powerful
> > module included with QTR called QTR Create ICC.  This module allows you to
> > profile the luminance of your printer's greyscale production and store it as
> > an ICC profile.  So when you come to print you can Let Photoshop Determine
> > Colors and convert the image file from whatever colour space you are using
> > for the file or workspace to a printer/output space that reflects your, well
> > err, printer output.  In this case it doesn't matter whether you have a
> > greyscale image tagged as GG2.2, GG1.8, DG20%, Adobe RGB, ProPhoto RGB or
> > any other.  When it leaves Photoshop it will be converted to a profile which
> > reflects your printer setup.  This is just like a colour (colour managed)
> > workflow.  The one difference is that it makes no attempt to output manage
> > hue - your greyscale hue is determined by the RIP or driver and ink/paper
> > setup you use to generate it.  In other words, there is no attempt to
> > maintain your nice neutral image on screen as neutral in the printer if you
> > have, say, selected a warm QTR curve.  Only the luminance axis is managed
> > and the print comes out warm as you wanted.  While this is the case, Roy is
> > working on a way to allow you to soft proof hue with the same ICC profile.
> > So when you set up a soft proof in the normal fashion in Photoshop you will
> > see the hue of the profiled printer setup (eg QTR with a warm curve selected
> > or Epson Adv B&W set to warm and darker - whichever settings you profiled
> > with QTR Create ICC) and the impact of the luminance management (the
> > compression to the reduced dynamic range of the printer) - for example a
> > nice warm image as it would print (reduced dynamic range and all).  THIS IS
> > AN EXTREMELY POWERFUL TOOL AND WELL WORTH THE COST OF QTR ON ITS 
OWN.  
> Even
> > if you are not using QTR as your RIP/driver, if you have an Eye-One Photo
> > and hence can use MeasureTool to read a step wedge printed using whatever
> > workflow you use, then you can likely benefit from using QTR Create ICC
> > (especially if you have a lumpy non linear output like black only).
> > 
> > Steve
> > 
> > 
> > * I noted Paul's RGB curve workflow as a possible exception because I
> > haven't fully thought it through.  Paul, in essence, targets a particular
> > greyscale profile with his curves.  This is quite different from getting
> > what you get with, say, black only (by this I mean you aren't able to change
> > the luminance profile of the greyscale generated by your printer in black
> > only mode - it is a black box and you get what you get) or managing, through
> > linearisation, your greyscale output.  Paul's curves in effect define the
> > transformation from workspace to print space.  With the other methods the
> > print space is constructed independently of the workspace (with the minor
> > exception that Clayton hunted out a workspace which best matched the print
> > space - a good starting point).  QTR Create ICC was designed to use colour
> > theory to manage the transformation between two independent spaces.
> > 
> > 
> > 
> > > From: Howard Shaw <glassman@b...>
> > > Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > > Date: Thu, 22 Sep 2005 08:08:56 +0100
> > > To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > > Subject: Re: [Digital BW] Re: B/W on the 9600
> > > 
> > > 
> > > Steve Kale wrote:
> > >> ...   If you are using Channel Mixer to convert to B&W
> > >> and want to be able to retrace your steps then saving this step as a layer
> > >> will, I believe, require you to keep the document in RGB.  This isn't such a
> > >> big deal except for the extra size etc.  If you are not worried about
> > >> keeping this layer then I would flatten and then go to GG 2.2 greyscale.
> > >> You can then easily save the document then bounce to Adobe RGB (which has 
a
> > >> gamma of 2.2) for your Photokit output sharpen and then print - discarding
> > >> the output sharpened file once it has printed.
> > >> 
> > >> 
> > > What is the advantage of converting to GG2.2 if you're workflow requires
> > > you to convert back to RGB? The same applies when using Paul Roark's
> > > curves for example. Retaining the original colour file and being able to
> > > alter the channel mixer settings etc right up until print time surely
> > > outweighs any advantage in converting?
> > > 
> > > Howard
> > > 
> > > 
> > > 
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> > > they are often being updated.
> > > 
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