Digital BW, The Print

>Absolutely white balance at the RAW stage is important. . . . 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. (large snip)

You're talking about white balance adjustments in Photoshop.  That wasn't
what the original poster asked about (at least I don't think it was).  He
asked whether he could leave the white balance setting on "auto"  so I think
he was asking whether the particular white balance setting in the camera
(i.e. auto, daylight, flash, fluorescent, etc.) mattered when shooting in
RAW mode.  It doesn't matter when in RAW mode with the digital cameras I've
owned because the raw data isn't affected by the white balance setting (i.e.
that setting as well as various other camera controls in effect become
inoperative when in RAW mode).


----- Original Message ----- 
From: "Pieris Berreitter" <pieris@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Tuesday, November 09, 2004 1:24 AM
Subject: Re: [Digital BW] White balance and B&W




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






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