Merge channels

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 resave the file as a DCS EPS file.

Open the grayscale images containing the channels you want to merge, and make one of the images active.
You must have more than one image open for the Merge Channels option to be available.
Choose Merge Channels from the Channels panel menu.
For Mode, choose the color mode you want to create. The number of channels appropriate for the mode appears in the Channels text box.
If necessary, enter a number in the Channels text box.
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.
Click OK.
For each channel, make sure the image you want is open. If you change your mind about the image type, click Mode to return to the Merge Channels dialog box.
If you are merging channels into a multichannel image, click Next, and select the remaining channels.
Note: All channels of a multichannel image are alpha channels or spot channels.
When you have finished selecting channels, click OK.
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.

Note: You cannot split and recombine (merge) an image with spot color channels. The spot color channel will be added as an alpha channel.