Social Media Design: How to Manipulate Photos with Photoshop’s Eraser Tool

By Janine Warner, David LaFontaine

You may find yourself needing to remove someone from, what would otherwise be, the perfect photo for your social media site. The Eraser tool is usually limited to those times you’ve made a mistake and need to scrub away some stray pixels or an effect that you’ve overdone. The Eraser tool can also be used to make a more complicated selection than can be done with the Magic Wand.

This technique can come in handy if you want to isolate your face from a group shot to use as a profile photo.

  1. With an image open in Photoshop, choose Layer→Duplicate Layer or press Ctrl+J (on a Mac, cmd+J).

  2. Click and hold the Eraser tool to bring up the menu options. Then choose Background Eraser.

    The Eraser and Magic Eraser tools are also nested under this tool in Photoshop. You can tell which one is active by the square dot next to it.

  3. Below the menus, click to select the Protect Foreground Color option.

    This option allows you to tell the Eraser tool to get rid of only the pixels in the color ranges you want, while not accidentally erasing the pixels you want to preserve. In this example, you want to get rid of the blue sky, while preserving the tan of the heads.

  4. With the Background Eraser tool active, Alt-click (on a Mac, Option-click) on the color you want to preserve.

    The cursor changes from a circle with a crosshair in it to an eyedropper. Use this to select a color in the area that you want to preserve.

    [Credit: cw istockphoto.com/Toni Flap]
    Credit: cw istockphoto.com/Toni Flap

    One thing that makes the Eraser useful is that you can quickly preserve different colors while isolating your subject from a background. Simply alternate using the Background Eraser with Alt-clicking/Option-clicking colors you want to keep, and you can work with even complex backgrounds where the colors are shifting and changing around the outlines on your subject.

  5. Click and hold, and drag the Background Eraser over the image to remove the background color.

    The Background Eraser removes the blue color, while not erasing the pixels in the tan heads. If all the colors you want to remove are not being erased, adjust the Tolerance.

    [Credit: cw istockphoto.com/Toni Flap]
    Credit: cw istockphoto.com/Toni Flap

You can quickly increase or decrease the size of your Background Eraser by using the bracket ([ or ]) keyboard shortcuts.

With your subject extracted, further isolate a single element if needed (such as a face) by switching to the regular Eraser tool. Click and hold the Eraser tool, and then start erasing the other faces (or torsos, or whatever) in the image.

The Eraser tool removes all pixels, regardless of color. Watch that you don’t get carried away.

[Credit: cw istockphoto.com/Toni Flap]
Credit: cw istockphoto.com/Toni Flap

To create a clean line on the extracted image, hold down the Shift key while holding the left mouse key down. Then “scrub” over the image, to force the cursor to erase in a perfectly straight line. This technique is useful if you want to have profile photo with a straight edge.

[Credit: cw istockphoto.com/Toni Flap]
Credit: cw istockphoto.com/Toni Flap

Like with a Magic Wand image, an extracted subject can be saved as a PNG file with the Transparency option turned on, or you can select this extracted subject and paste it into another image to make a collage or composite.