Digital BW, The Print

Wow sounds like a lot of work.  I started playing with channel mixer as a
result of some desaturated colour work - take a colour image and work it up
to satisfaction, then apply a channel mixer layer with dramatic mix (eg Red
200%, Green -50%, Blue -50%) and then set the opacity of this layer at
around 65% for a colour/B&W hybrid.  I am still not conceptually getting
what is happening when, with monochrome checked, a channel is set to greater
than 100% or at a negative value.....but I like the results.


> From: "Paul D. DeRocco" <pderocco@...>

> 
> In the general case, the Channel Mixer just lets you do any linear mixing of
> channels, either to a RGB target (in which case there are three sets of
> sliders) or to monochrome. It is really only widely useful in the latter
> case, so I can't help wondering why Monochrome isn't the default. Also, the
> constant slider is really just there for completeness--it's rarely useful,
> either.
> 
> And you're right that in general you want the other three values to add up
> to 100. For an underexposed image, you might correct for it by making the
> sum larger, but in general I think it's best to do that afterward with
> Curves or Levels.
> 
> And you're right that you can get some really dark IR-like skies by
> subtracting green or blue from red.
> 
> The main thing to keep in mind is that the Channel Mixer isn't likely to
> produce a finished image. It just gives you a fairly simple global way to
> mix them, but you still need to apply a curve to get the different zones in
> the right place.
> 
> I sometimes use split channels, too, in images where I need a very different
> mix in different part of the picture. I split them, layer them, and then
> paint the layer masks to control the mix. However, for even more control,
> duplicate an image, use the Channel Mixer twice to optimize different parts
> of the picture, then layer them and paint the layer mask. Or sometimes, I
> just use the channel mixer, then use the history brush to paint back some of
> the original image, if the mix produces generally pleasing results but a few
> clipped highlights here and there.
> 
> --
> 
> Ciao,               Paul D. DeRocco
> Paul                mailto:pderocco@...
>>