Digital BW, The Print

I was experimenting with this a few days ago.

Absolutely white balance at the RAW stage is important. It can, in 
fact, become critical if you are concerned about highlight detail 
that is near clipping. In Photoshop's CS RAW import, adjusting color 
balance has the effect of repositioning the R, G, and B channels in 
the histogram. In an example here, highlights in my image clip at 
5500K but are smooth at 2500K.

What might be good is if the RAW importer would apply contrast FIRST, 
and then WB. That way you could decrease contrast (shrink the 
histogram) and then adjust WB (which can grow the histogram), without 
clipping. But it doesn't work like that, so you have to be very 
careful. The other pie in the sky solution would be a RAW to true 16-
bit-space converter. Photoshop CS does not do this; instead, 16-bit 
space is really 10-, 12-, or 14-bit space depending on camera.

The only solution I know of is to watch the histogram carefully as 
you drag your white balance slider around.

These are 100% crops taken from a Canon P&S digicam. All RAW sliders 
were set to zero (contrast, exposure, etc). I tried Bibble and 
BreezeBrowser as well on these files, but both of these retained 
highlights at the expense of clipping the shadows. I do not have 
capture one. The images are in color and clearly show that 
information is lost in the highlights which could not be regained.

http://www.pmb.net/a/psraw_2500.jpg
http://www.pmb.net/a/psraw_5500.jpg

-Pieris

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Roger Howard 
<rogerhoward@m...> wrote:
> 
> On Nov 7, 2004, at 8:50 PM, Paul D. DeRocco wrote:
> 
> >
> >> From: Stephen Kobrin [mailto:kobrins@w...]
> >>
> >> If I am ultimately going to convert a digital image (saved in Raw
> >> Mode) to B&W is there any point in worrying about getting the 
white
> >> balance exactly right or does it suffice to leave it on 
automatic?
> >
> > Color to B&W conversion usually involves major transformations, 
not 
> > just
> > blindly converting to grayscale. For instance, the Channel Mixer 
lets 
> > you do
> > things like set the red to 150% and the blue to -50%, to make 
really 
> > dark
> > skies. If you're like me, you'll probably yank the curves all 
over the
> > place, too. By then, you'll have swamped any minor differences in 
the 
> > color
> > levels you get from using different white balances.
> 
> Agreed - but just to be literal, white balance settings *do* affect 
B&W 
> conversion; whether they are a major factor just depends on how 
you're 
> doing the conversion. Yeah, I usually use extreme moves in Channel 
> Mixer, often with an additional Curves adjustment layer beneath it. 
But 
> the right WB setting to preserve the right channel separation 
(before 
> you mix them back down) is important, in my experience.
> 
> -R