Digital BW, The Print

On Nov 8, 2004, at 12:19 PM, Paul D. DeRocco wrote:

>
>> From: Roger Howard [mailto:rogerhoward@...]
>>
>> 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.
>
> I don't think WB does anything at all to channel separation--it just 
> applies
> gains to the three channels. Correct me if I'm wrong.

Now I'm afraid we're going to confuse the poor OP :)

WB tweaks the three channels differently; this means that if you then 
do a channel mix, the results will be different depending on what WB 
you started with. Maybe we mean something different by separation - I 
was using it non-technically, to refer to the emphasis or de-emphasis 
of different ranges of color (and how those are represented in the 
three channels). WB definitely affects overall color, and if pushed too 
far in either extreme can easily start to loose color detail 
(separation).

In other words, if I take the same RAW file and process it twice... 
once at 2400K and once at 9000K... then apply the SAME channel mixer 
settings to it... I'll get different B&W results.

Cheers,

Roger