Digital BW, The Print

> From: Steve Kale [mailto:stevekale@...]
>
> 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.

If a channel's gain is set to greater than 100%, it boosts the contrast of
that channel. This is sometimes useful, especially if combined with a
negative value in another channel, but can lead to blown highlights in areas
that are predominately that color.

If a gain is set to a negative value by itself (along with a postive
constant), that would invert the image. However, negative values are
primarily useful, as you found out with your sky experiments, for darkening
a part of the picture that's a different color from the rest, as opposed to
creating a negative effect.

You can do a lot of bogus thins with the Channel Mixer, and it's certainly
not the be-all end-all of B&W conversions, but people use it because often
it provides an easy way to do some fairly obvious things. Indeed, if I just
want to use a single channel as-is, and discard the other two, I prefer the
channel mixer over Split Channels because the latter clobbers the file name
and discards the EXIF info.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...