How to Rearrange, Rename, and Split Channels in Photoshop CS6
Although you can’t shuffle or rename color channels in Photoshop CS6, you can do so with spot and alpha channels. To move a spot or alpha channel, simply drag it up or down in the Channels panel. When you see a dark line appear where you want the channel to go, release your mouse button.
You can move a spot or alpha channel above a color channel only in a multichannel image. In short, in a multichannel image, each channel becomes an independent spot channel, and the channels no longer have a relationship with each other. Multichannel images don’t support layers.
To rename a spot or alpha channel, double-click the name in the Channel panel and type a new name. You can also select Channel Options from the panel menu.
You can split the channels of your image into separate images in separate files. For example, you see the Red, Green, Blue, Alpha, and Spot channels split into individual channels. Choose Split Channels from the panel menu. When you do so, your original image closes. The channel files have the name of your original image plus the channel name.
You can split channels only on a flattened image — in other words, an image that has no individual layers.
Be sure to save all changes in your original image before you split it because Photoshop closes your file.
You might want to split channels if you need to save your original file in a format that doesn’t preserve channels — such as EPS, which doesn’t support alpha channels. Or you may want to split channels to merge them later on.