The Channels tab displays the three RGB channels, showing the current red, green, or blue color values of each pixel in your image. The RGB channel thumbnails are grayscale representations of each color channel with white representing 100% color and black representing no color.
The RGB channels each have an
icon, so you can look at your image in a single color channel. Click
off the eye icon in the Blue and Green channels, so
that only the Red channel is visible. Bright red in the red channel is
the equivalent of a maximum red value for that pixel; black means that
the pixel has no red at all in it. You will see bright red for areas
that are white or bright red. If all three channels have maximum values
for an area, that area is white in the actual image.
The RGB channels are always active when a layer is active. They display the color values of all visible layers, not just the active one. Unlike layers, the RGB channels can all be active at the same time. You can also choose to work in one or two specific color channels by clicking on the appropriate channels to activate the ones you want and deactivate the ones you don't want.
You can create new channels by clicking the
button. This will bring up the New Channel dialog where
you can set name, color, and fill amount of the new channel. If you
want to alter the values later on, you just double click on the channel
which will bring up the Edit Channel
Attributes dialog. Normally you don't work with extra
channels, but they can be very handy for creating and storing
selections.
If you right click on the layer name you will be able to access the layer menu. In the layer menu you have access to several other layer commands, see Chapter 6.
An experienced user can also use them to create patterns and
advanced colored images. The channel stack tools
and
are more or less only useful when you work
with those kind of images.
You are able to store a selection as a channel with the
rightclick Select Save To
Channel command. This creates a new channel
where you can paint, erase, and perform any other drawing function.
The altered channel can be turned into a selection again by clicking
on the
Channel To Selection
button. This is a very convenient way to alter selections and store
several selections. In fact, you can create selections from scratch
by creating a new channel, altering it, and then applying
Channel To Selection.