Digital BW, The Print

Thank you to all for the informative replies.
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Anthony G. 
Atkielski" <anthony@a...> wrote:
> David Sinai writes:
> 
> > I was curious to see if the histogram of this file would be
> > different if the file was converted to 8 bit. After converting 
the 
> > file to 8 bit, I reviewed the histogram and so no changes.
> 
> The histogram only shows data with 256 levels, so you can't see any
> difference between 8-bit and 16-bit modes with the histogram.  To 
show
> the 16-bit data, you'd need a histogram 65,536 pixels wide, which
> obviously is not practical.  In 16-bit mode, every pixel you see
> horizontally in the histogram is actually the sum of 256 different
> levels (256 x 256 = 65,536 levels).
> 
> > Shouldn't there be a different histogram once the file is 
converted
> > to 8 bit?
> 
> It would be nice, but as explained above, it wouldn't fit on the 
screen.
> 
> > Going from 16 bit to 8 bit means that the tonal range has
> > been reduced, correct?
> 
> Yes.
> 
> > More importantly, I could not detect any visible differences on 
the
> > screen when the image was in 8 bit vs. 16 bit.
> 
> In black and white, very few monitors can show any difference.  
And you
> must be in at least a 32-bit color mode to even be able to hold any
> difference in display memory (and that's still smaller than the 48-
bit
> mode you'd need to show full 16-bit images).
> 
> > I decided to work with the 8 bit file as there are more PS
> > features available this way.
> 
> But there is also less data.
> 
> The advantage to 16-bit mode is that you have far more headroom for
> modifications.  For example, if you need to drastically change the
> curves in the image, you can do so in 16-bit mode with almost no 
loss of
> quality, whereas you'll get serious posterization in 8-bit mode,
> particularly after multiple operations, since the effect is 
cumulative.
> 
> > Should there be any discernable tonality differences on a print
> > created with a 16 bit file vs. 8 bit when printing with an Epson 
> > 2200 using the BO method?
> 
> No.  The advantage to 16-bit is in the extra data you have for
> manipulation.  You don't need to stay in 16-bit mode once you are
> finished retouching and adjusting the image, and you can store it 
in
> 8-bit mode if you want (just remember, once you move it to 8-bit 
mode,
> you won't have as much data if you ever decide to modify it again).
> 
> > I printed the 8 bit and the 16 bit file and saw no differences. 
Is
> > this what you would expect?
> 
> Yes.
> 
> > Everything I've read, says to stick with 16 bit.
> 
> As long as you are adjusting or retouching the image and/or you 
expect
> to do so in the future, 16-bit is better than 8-bit.  For actually
> printing the image and archiving it, though, it doesn't matter, 
since no
> display or print device can really resolve more than 256 levels, 
anyway.
> 
> > Does the rule "Stay in 16 bit" apply when printing BO on Epson 
2200?
> 
> No.  It doesn't apply for any kind of printer or display.  None of 
them
> can come close to resolving 65,536 different gray levels.