Merging channels

Multiple grayscale images can be combined into a single image. Some grayscale scanners let you scan a color image through a red filter, a green filter, and a blue filter to generate red, green, and blue images. Merging lets you combine the separate scans into a single, color image.

Note: You can also blend the data in one or more channels into an existing or new channel. (See Mixing color channels (Photoshop).)

The images you want to merge must be in Grayscale mode, have the same pixel dimensions, and be open. (See Changing the pixel dimensions of an image.) The number of grayscale images you have open determines the color modes available when merging channels. For example, you can't merge the split channels from an RGB image into a CMYK image, because CMYK requires four channels and RGB requires only three.

Note: 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.

To merge channels:

1. 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 opened for the Merge Channels option to be available.

2. Choose Merge Channels from the Channels palette menu.
3. For Mode, choose the color mode you want to create. If an image mode is unavailable, it is dimmed. The number of channels appropriate for the mode appears in the Channels text box.
4. 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 a multichannel image with two or more channels.

5. Click OK.
6. For each channel, make sure the image you want is open. If you change your mind about image type, click Mode to return to the Merge Channels dialog box.
7. If merging into a multichannel image, click Next, and repeat step 6 to select the remaining channels.

Note: All channels of a multichannel image are alpha channels.

8. When you are 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.