Digital BW, The Print

Hi Steve.

When using channel mixer, I usually start out by inspecting the 
individual Red, Green and Blue channels.  Channel mixer will "mix or 
blen" these channels together to give you a composite image, and if 
you check the monochrome box, a composite B&W image.  For many 
images, I find red and green to have the most useful information, and 
blue tends to have more noise.  This can vary tremendously from image 
to image.

So, when I open channel mixer, I now have a little feel for what I 
want to do.  I generally try to keep the sum of the 3 sliders to add 
up to 100, or thereabouts.  For many images 40R, 50G and 10B isn't a 
bad starting point.  Increasing the Red slider increases the 
influence of the red channel in your final output.  I try to get the 
most pleasing overall tonality in channel mixer, then I add a curve 
adjustment layer on top of it.

There are probably lots of tutorials on channel mixer on the web.  
Here is one link to a lot of B&W actions.

Lou

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Kale" 
<stevekale@b...> wrote:
> 
> I typically use the split channels method to render B&W from colour 
but have recently 
> begun playing with the channel mixer.  I guess I need some help as 
to what the sliders do 
> - I am simply fiddling in the dark at the moment.  Should the sum 
of the Red, Green and 
> Blue slider percentages ideally add to 100?  What is the purpose of 
the Constant slider?  If 
> a channel is raised beyond 100% what does this mean? (I found that 
some quite dramatic 
> effects can be produced by say raising the red to 200% and having -
50% for the other two 
> channels but it seems that skies can get torn up by doing this.)
> 
> Thanks
> 
> Steve