Digital BW, The Print

Hello Guhan,

These aren't stupid questions, this is probably the most confusing
part about all this.

>I've just read Clayton Jones' article Using Color Settings
>and Workspace Profiles for Grayscale Printing, and I'm not 
>getting it.  I understand the points about dot gain, gamma, using 
>curves, etc.  What I don't understand is the WYSIWYG thing.  If my 
>monitor is calibrated (lets say with an EyeOne Display), and I have 
>a profile then for it (this would be considered the front end... 
>correct?).  And lets say I'm using EEM on an R2400, epson driver.  
>I have WYSIWYG don't I?  Doesn't the epson driver take care of that?
>Is this for times when one can't get a pre-made profile?  If I use a
>commercial RIP, is this issue also a null point?  (I thought that
>calibrating my monitor and using a RIP was to get WYSIWYG).  

The workflow described there is for people who aren't using
calibrated systems and special profiles, and the printer profile is
set to SAS ("Same As Source" or "No Color Management" in CS2).  My use
of the terms Front End and Back End is to get away from the technical
terms (because there are several overlapping ones which tend to be
confusing) and provide a conceptual idea of the push-pull relationship
between the image profile (front end) and the printer profile (back end).

The main point of it is that the front end profile affects how the
image pixels are displayed on screen, and (assuming the back end is
SAS), changing it (assigning, not converting) will not affect the
print. With an uncalibrated workflow the quality of the WYSIWYG, while
generally quite good with well chosen settings, can vary slightly with
extremely high or low key images, and it is possible to change the
screen image to be a closer match to the print in those cases by
assigning a different front end profile.

The approach is based on a workflow where an initial default gray
space profile (selectable by you in the "color Settings" window) is
used when the image is converted from color to BW (or when a neg is
scanned).  This initial profile determines the actual grayscale values
of the pixels in the image.  Because of this, it, of course, has a big
effect on the resulting print.  Another important setting is the
printer driver gamma setting (1.5, 1.8, 2.2 - or Light, Normal, Dark,
etc in ABW printers), which affects how the image pixel values are
sent to the printer.  The combination of these two things determines
the print values and the WYSIWYG quality.  

The reason I recommend using DG20 as the default gray space and driver
gamma 1.8 (or Light in ABW), is that this gives me very good WYSIWYG
and keeps good detail separation in the dark shadow zones.  This isn't
carved in stone, some people prefer other combinations.  I recommend
these as a good starting place that will produce very good results
right out of the starting gate.  I actually use a custom DG18% default
profile.

The initial "gray space" (or "working space" or "document space" or
"image profile", take your pick - there are nuanced differences in
meaning for these, but they are often used interchangably which adds
to the confusion) remains in effect unless the image is "converted" to
another (converting actually changes the pixel values).  However, a
different profile can be "assigned" without changing the pixel values.
Assigning a different front end profile changes how the pixels are
interpreted on screen, but the resulting print doesn't change because
the image pixels haven't changed.  This allows us to change the screen
image to be a closer match to the print, if necessary.  In actual
practice I do this only rarely, usually for very high or low key
images that are out on the extreme end of the scale.

All of this is pretty much irrelevent for people using calibrated
color management approaches because it's a completely different
conceptual framework.  I hope this has helped and not made it worse!

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm