Digital BW, The Print

> From: Bob Frost <bob@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 15 Sep 2005 18:23:14 +0100
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] Re: Problems printing with R2400
> 
> Steve,
> 
> On a Windows PC, choosing 'Let printer determine colors' means that CS2
> sends the image with its working space profile to the printer driver. The
> printer driver then uses Windows ICM2 to do the conversions necessary from
> the working space to the appropriate printer profile, assuming you have
> chosen the correct setting (color controls, photoenhance, icm) for this in
> the printer driver and not turned color management off in the printer
> driver. This is the normal Epson mode for printing with its profiles. These
> driver settings also include the new AdobeRGB setting that apparently
> enhances the color gamut of the R2400.
> 
> On the other hand, if you want to use custom profiles, you usually turn
> color management off in the printer driver and choose 'Let Photoshop manage
> colors' in CS2. Then Photoshop uses its own ACE conversion software to do
> the conversions from working space to custom printer profile, and the
> printer driver does not do any color management. You may occasionally leave
> color management on in the printer driver (see below).
> 
> Then if (with your third hand) you want to print a printer profiling target,
> you choose Color Management off in CS2, and choose whatever setting you are
> going to use for printing in the printer driver. This will usually be no
> color management, but some get better results with earlier printers by using
> color controls/photoenhance in the driver.
> 
> And (with your fourth hand) if you want to print using the AB&W setting, NOT
> using custom profiles, you select 'Let printer determine colors' in CS2 to
> make sure that CS2 is not doing any color conversions. The printer driver
> will then do whatever it wants to give you the AB&W; I would have thought it
> would take notice of the working space profile, but I haven't yet sent any
> with different working spaces to test this.

The behaviour of a Mac vs a PC here is identical (albeit the GUI may look
different.)  Whether you use custom profiles or not is irrelevant - only
which CMM you want to use, PS's CMM or the printer driver's (or none at
all).  The first two of PS's options are really as simple as that.  So Let
Photoshop Determine Colors means you want to use colour management and have
PS do the conversion with its CMM.  Let Printer Determine Colors says you
want to colour manage but want the printer driver CMM to do the conversion.
In this case, the image file and the colour profile (custom or otherwise)
are sent to the printer driver.  No Color Management simply sends the image
file without a profile.  (In the first and third you obviously have to tell
the printer driver to not do any colour adjustment, in the first instance
because it has been done and you don't want it done twice and in the second
because you don't want to colour manage.)

The question at hand simply boils down to whether the printer driver, when
in Advanced B&W mode, makes use of any profile that was sent with the image
file (by someone selecting Let Printer Determine Colors).  I believe it does
not, ie that the profile is discarded and the image document is therefore
not ICC colour managed.  For similar reasons, Epson would not want you to
have PS do any colour management such that the image file is adjusted prior
to reaching the printer driver.  This makes a lot of sense.  The profiles
that are used in colour management are colour profiles and do not, as I have
said before, describe the stimulus-response behaviour of the printer when
driven in that mode.  Therefore, it does not surprise me that the early beta
testers of the new printers in their reviews used it in a non-colour managed
fashion. 

But a simple test would demonstrate things either way and I am happy to be
proven wrong.  Print a step wedge with No Color Management and measure the
results.  Print step wedges then using each of PS and the printer driver to
do the colour management to the printer ICC profile for the paper/ink you
are using. Does the output with Let Printer Determine Colors look more like
No Color Management or Let Photoshop Determine Colors?  That will tell you
whether the profile sent to the printer with Let Printer Determine Colors is
used or not.  Remember at best it can only use some sort of luminance axis
of the profile because you determine hue in the driver.  So the question is
whether the printer driver actually pulls this luminance axis information
from the profile and makes use of it.  I doubt it.  Even if it does,
personally I prefer to measure directly the luminance stimulus-response
behaviour of the driver in AB&W mode and use the PS CMM to adjust my image
file, without further ICC colour management in the driver.  This direct
profiling via QTR Create ICC can be much more accurate (I use 51 samples).

And yes it was good to see the Aussies beaten in the Ashes for the first
time since 1987 as it was good to also see the England Lions get thrashed
while touring New Zealand!

Cheers

Steve

PS:  If you run the test be sure to let us know how it turns out.  Thinking
about it further, having a conversion to at least some sort of profile for
the paper/ink one is using is likely better than nothing (whether PS does it
or otherwise).  Even if it is a colour profile then at least the black and
white points (and some greyscale observations) are then made use of and some
sort of order brought to the greyscale compression.  The image file sent to
the printer would still be greyscale but it's luminance would have been
adjusted for that of the printer - in essence a cruder version of what QTR
Create ICC does in a more focused manner.  This assumes of course that the
linearity of the printer in colour mode is consistent with that in AB&W
mode.  Like I said, I personally prefer to measure and profile the latter
directly but for those without an Eye One using the colour profile may be of
some help although only testing would tell.