How to Create Channel Masks in Photoshop CS6

Photoshop CS6’s channel masks are probably the most time-consuming masks to use because they require a lot of manual labor. Not heavy lifting, mind you, but work with the tools and commands in Photoshop.

It is, however, time well spent. Channel masks can usually accurately select what the other Photoshop tools can only dream about — wisps of hair, tufts of fur, a ficus benjamina tree with 9,574 leaves.

You can create a channel mask in a lot of ways, but here is one that works most of the time. To create a channel mask, follow these steps:

  1. Analyze your existing channels to find a suitable candidate to use to create a duplicate channel.

    This is usually the channel with the most contrast between what you want and don’t want. For instance, in this example, the Blue channel provided the most contrast between the windmills and the sky and the background, allowing easier masking of the windmills and sky.

    To duplicate the channel, drag your desired channel thumbnail to the New Channel icon at the bottom of the Channels panel. After you duplicate the channel, it then becomes an alpha channel and is named (channel) copy.

  2. Make sure the alpha channel is selected in the Channels panel and choose Image→Adjustments→Levels.

    Using the histogram and the sliders in the Levels dialog box, increase the contrast between the element(s) you want and don’t want selected. Click OK when you’re done to close the dialog box.

  3. Select a tool, such as the Brush or Eraser tool, and paint and edit the alpha channel to refine the mask.

    The combo of the Brush and Eraser set to Block mode cleaned up the mask.

    [Credit: ©iStockphoto.com/selimaksan Image #16953126]
    Credit: ©iStockphoto.com/selimaksan Image #16953126
  4. When you complete the mask, click the Load Channel as Selection icon (the dotted circle icon on the far left) at the bottom of the Channels panel. Then, click your composite channel at the top of the list of channels.

    This step loads your mask as a selection, giving you that familiar selection outline. You can also use the keyboard shortcut: Ctrl-click (Command-click on the Mac) directly on the alpha channel to load the mask as a selection. Make sure your marquee selection is surrounding what you want selected. If not, choose Select@→Inverse.

    Your selection is now ready to go.

  5. You can leave it within the original image, or drag and drop it onto another image with the Move tool.

    If you’ve done a good job, nobody will be the wiser that the two images never met in real life.

    [Credit: ©iStockphoto.com/selimaksan Image #16953126 and AlexMax Image #7458774]
    Credit: ©iStockphoto.com/selimaksan Image #16953126 and AlexMax Image #7458774
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