You can copy a channel and use it in the current image or another image.
For example, you may want to use the Duplicate Channel feature to create a channel mask; or you may want to back up a copy of a channel before you edit it.
If you are duplicating alpha channels between images, the channels must have identical pixel dimensions. You cannot duplicate a channel to a Bitmap‑mode image.
Choose a destination. Open images only 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.
The destination image does not have to have the same pixel dimensions as the duplicated channel.
Drag the channel from the Channels panel into the destination image window. The duplicated channel appears at the bottom of the Channels panel.
Choose Select > All, and then choose Edit > Copy. Select the channel in the destination image and choose Edit > Paste. The pasted channel overwrites the existing channel.
You can split channels of flattened images only. Splitting channels is useful when you want to retain individual channel information in a file format that doesn’t preserve channels.
The original file is closed, and the individual channels appear in separate grayscale image windows. The title bars in the new windows show the original filename plus the channel. You save and edit the new images separately.
Multiple grayscale images can be combined as the channels of a single image. The images you want to merge must be in grayscale mode, be flattened (have no layers), have the same pixel dimensions, and be open. The number of grayscale images you have open determines the color modes available when merging channels. For example, if you have three images open, you can merge them into an RGB image; if you have four images open, they can become a CMYK image.
If you are working with DCS files that have accidentally lost their links (and so cannot be opened, placed, or printed), open the channel files, and merge them into a CMYK image. Then re-save the file as a DCS EPS file.
You must have more than one image open for the Merge Channels option to be available.
If you enter a number that is incompatible with the selected mode, Multichannel mode is automatically selected. This creates a multichannel image with two or more channels.
All channels of a multichannel image are alpha channels or spot channels.
The selected channels are merged into a new image of the specified type, and the original images are closed without any changes. The new image appears in an untitled window.
You cannot split and recombine (merge) an image with spot color channels. The spot color channel will be added as an alpha channel.