Photoshop CS6 Tutorial
How to Save Selections as Channels in Photoshop
Channels have many uses in Photoshop. The more common uses include saving selections and defining transparent areas.
For instance. you may have an object or some text that is headed to a 3D or Video software package. By saving an Alpha channel, the 3D and Video software knows which areas are opaque and which areas are transparent.
Open an image in Photoshop (File > Open). In our example we have letters colored with shades of red, green and blue to illustrate how Channels work.
Open the Channels panel (Window > Channels).
Notice how there is a Red, Green and Blue channel. The RGB channel at the top is the composite of the three channels below. Click on each of the Channels and take a look at which parts of the grayscale image are light and which areas are dark.
Once the three grayscale images are combined, a full color version of the image is rendered. The red, green or blue light is allowed to pass through the lighter areas of its assigned channel,
Since channels are grayscale images, you can apply brushes, levels, curves and filters. The modifications can be applied to any channel except the original Red Green or Blue channel.
Sometimes one of the Channels is a good starting point for creating an image mask. To use this technique, duplicate one of the existing channels, then clean up the mask with Levels, Brightness and Contrast and the Brush tool.
A Channel can be used as an Alpha channel when used with other software packages such as Maya or After Effects. Alpha channels are used to make certain image areas transparent.
Masks are also used to save a selection for future use. To make a selection, outline your object with one of the Marquee tools or Selection tools.
Save your selection by clicking the Save Selection as Channel icon in the Channels panel, then deselect your object (Cmd/d (PC - Ctrl/d)).
Once a Channel is saved, you can easily reload it to make a selection. To load a channel, choose Select > Load Selection, then select your channel.
Channels and Image Modes
As you have seen, RGB images have a red, green and blue channel. CMYK images are built with a cyan, magenta, yellow and black channel. Grayscale images have only one channel.
More Ways to Load a Selection
In Step Ten we described how to load a selection. To load a selection, you can also Cmd-click (PC - Ctrl-click) the channel icon in the Channels panel or simply click the Load Channel as Selection icon at the bottom of the Channels panel.