On Sun, Mar 8, 2009 at 11:20 AM, Sven Neumann wrote:

> I think you are missing the bigger picture here. Channels are not only
> about saved selections. If they were, we should indeed declare then as
> such. But channels are also used for simulating spot colors and as such
> they are much more closely related to the color components that are
> shown at the top of the dialog. There are more interesting things that
> can be done with channels. Unfortunately this is not very well covered
> in the GIMP documentation (the old manual by the Kylanders was better in
> this regard). That's why it is even more important that we keep this
> close to the Photoshop channels dialog. Then users can at least benefit
> from the documentation that exists for PS.

I dug up a copy of this manula, and discovered a couple things after
playing with channels in 2.6.4 and 2.6.1 on Ubuntu.

In the instructions, it states:
Open the Channels tab and create a new channel. In the New Channel
Options dialog, set this channel to 100% Fill Opacity. Click the black color
swatch to access the Color Selection dialog, and choose a nice color (this will
be the first plate to be printed). Name the channel “navy blue” or the
like, depending
on what color you chose. Click on the OK button.
Paste (right-click|Edit|Paste) the image into this channel.

It seems you can no longer paste into a channel.  You have to take a
greyscale copy and drag it from the layer panel to the channel panel.

I also tried to duplicate a couple of PS n-tone tutorials, like this
one: http://www.dpchallenge.com/tutorial.php?TUTORIAL_ID=23

I discovered that they can be duplicated in gimp with a few
changes...namely, the channel has to be inverted, and the curves must
be adjusted "backward" (i.e black on the left).

I was able to get some good success (I think) of a tritone with this method:

-Rob A>
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