Duplicating channels

You might duplicate an image's channel to make a backup before editing the channel. Or you might duplicate alpha channels to a new image to create a library of selections to load into the current image one by one--thus keeping the file smaller.

If you are duplicating alpha channels between images, the channels must have identical pixel dimensions. (See Creating new images.)

Note: You cannot duplicate a channel to a Bitmap-mode image.

To duplicate a channel using the Duplicate command:

1. In the Channels palette, select the channel to duplicate.
2. Choose Duplicate Channel from the Channels palette menu.
3. Type a name for the duplicate channel.
4. For Document, do one of the following:
• Choose a destination. Only open images with pixel dimensions identical to the current image are available. To duplicate the channel in the same file, select the channel's current file.
• Choose New to copy the channel to a new image, creating a multichannel image containing a single channel. Type a name for the new image.
5. To reverse the selected and masked areas in the duplicate channel, select Invert.

To duplicate a channel within an image by dragging:

1. In the Channels palette, select the channel you want to duplicate.
2. Drag the channel onto the New Channel button at the bottom of the palette.

To duplicate a channel to another image by dragging or pasting:

1. In the Channels palette, select the channel you want to duplicate.
2. Make sure that the destination image is open.

Note: The destination image does not have to be the same pixel dimensions as the duplicated channel.

3. Do one of the following:
• Drag the channel from the Channels palette into the destination image window. The duplicated channel appears at the bottom of the Channels palette.
• Choose Select > All, then choose Edit > Copy. Select the channel in the destination image and choose Edit > Paste. The pasted channel overwrites the existing channel.