Digital BW, The Print

Hello Steve,

>As for BO with 1.8 gamma or 2.2 gamma, it really is a very basic
>statement that I was making.  If your printer had the same "space" 
>as your "workspace" and "display" space, ie would reproduce the 
>same density for any particular pixel value (8, 16 bit or 
>otherwise), then none of this topic would be an issue - we would 
>see and print and store the same thing.  The closer the spaces are,
>the less the mismatch and hence the lesser is the "matching
>monitor and print" issue.

A nice theory, sounds good so far.


>Since most people work in Gray Gamma 2.2 for B&W

What do you mean by this?  There are three different places to assign
things: the image profile, the printer profile, and the driver gamma
setting.  What does "work in Gray Gamma 2.2" mean in terms of these
three settings?  And how do you know that "most people" do whatever it
is you mean?


>it would make sense to have a print space gamma as close to this as
>possible.  

What do you mean by "print space gamma"?  Do you mean the printer
profile setting or the driver gamma setting?


>Choosing 1.8 rather than 2.2 in the Epson driver simply makes the
>mismatch worse (and, by corollary, the adjustment of the image 
>needs to be greater to get satisfactory prints vs if you had 
>selected 2.2).

Again, a nice theory, but it doesn't hold up in the real world.  In
actual use I find just the opposite. Selecting 2.2 ends up requiring
more work.  It has been over two years since I worked this stuff out,
so I decided to go back and test your theory to see if I was missing
something.  This morning at church I made a portrait of a woman, using
a digital camera, so I decided to use it as a test case. I opened it
in PS and did a straight grayscale mode conversion (I wanted to do as
little manipulation as possible for this test).  

The pic was well exposed and the BW image is very pleasing and will
not require much work.  The grayscale tones have values that closely
match the color image (IOW, the image doesn't look under or over
exposed in comparison to the color version, and the contrast is
likewise very close).  Keep in mind that this image was automatically
tagged with my default DG18% profile, and the printer profile is
always set to Same As Source. 

I then made a straight print (no curves, no manipulations) with my
standard driver gamma setting of 1.8.  The resulting print looks just
like the screen image (given the differences between a print and a
screen).  These are the settings that I have found give the best
WYSIWYG.

Then I tried your way.  First I set the image profile to GG 2.2 (which
immediately made the image extremely dark on screen, not at all
resembling the original).  I left the printer profile at SAS (because
it is the same as changing it to GG2.2, so in effect the printer
profile is now also GG2.2), and printed it with the driver gamma set
to 2.2.  The resulting print was similar to the first print, but was
slightly darker and had significantly lower contrast, resulting in a
duller and less pleasing print).  And of course there was terrible
WYSIWYG - the screen image was very dark and bore little resemblance
to the print (or the original).

So by doing it your way I got a duller starting print and terrible
WYSIWYG, which means the image would require more work to get a nice
print, and it would be done under more difficult conditions (poor
WYSIWYG), which would probably require more time, paper and ink.  

Now, what actually happenend here?  First, setting the image profile
to GG2.2 made absolutely no difference in the print.  This is because
whenever the printer profile is the same as the image profile (SAS) it
has the opposite affect and cancels out whatever the image profile
does (as far as what goes to the printer - the image profile does
affect what we see on screen).   So the only thing that affected the
print was the driver gamma setting.  Just to reassure myself on this
point, I made a 3rd print with image profile back at DG18 and driver
gamma at 2.2, and got an identical print to #2.  So the only thing
that made any difference in the print was the driver gamma setting.

So why do I prefer 1.8 to 2.2?  Because I tried all three available on
the 2200 (1.5, 1.8, 2.2) and found that 1.8 gives a print that most
closely resembles a screen image with profile at DG18 or 20, and I
prefer DG18 or 20 for the image profile because it produces a screen
image that most closely resembles the original image, which in most
cases is well exposed and closely resembles the original scene.  In my
experiments I found that driver gamma 1.5 prints were lighter and more
contrasty than 1.8 prints, and 2.2 prints were darker and less
contrasty.  So the main points are these:

1) With printer profile set to SAS, the image profile does not affect
the print, it only changes the screen image.  Therefore we can choose
whatever image profile that gives us the best WYSIWYG.  This may vary
depending on monitor and graphics card.  I recommend DG20 in the
article because it's in the middle of the brightness range of all the
canned profiles and is a good starting place.  For my own setup, I
found that a custom DG18 curve was an improvement over DG20.

2) The only thing that affects the print (other than changes to the
image itself) is the driver gamma setting.  I recommend 1.8 because
it's in the middle of the brightness/contrast range of the three
choices, and, from experience, produces the most well balanced print,
requiring less work.  Also, because because 1.5 and 2.2 significantly
alter the contrast as well as brightness, 1.8 is also the easiest to
find a matching image profile for good WYSIWYG.

3) Putting it all together, I have found that the combination of image
profile at DG18 or 20, printer profile at SAS, and driver gamma at
1.8, produces 
- a screen image that most closely resembles the original
- the most well balanced starting print
- the best WYSIWYG

So it's a "straight through" workflow, with all three stages looking
alike, requiring the least amount of work under the best possible
conditions. 

None of this is theory.  It is the result of countless hours of trial
and error experiments (and an ungodly amount of ink and paper - MIS
loves me <g>).  It's easy enough, anyone can try it for themselves in
a few minutes.

Regards,
Clayton


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