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A3 - Background Removal - Part 1

When we edit photos, we quite commonly will want to separate the subject of an image from its background. This could be useful for:

  • Swapping out the background
  • Moving the subject to a different photo and blending it in
  • Applying certain effects or filters to just the subject or the background

The main challenge here is removing the background from the original image. Gimp gives us several strategies to do this, and in this assignment we'll look at a few.

But First... The Alpha Channel

You want to ensure that the pixels you delete turn transparent rather than white. If you open an image that doesn't already have an alpha channel (thus supporting transparency), you need to add one.

Do this by right-clicking on the layer, then selecting Add Alpha Channel. If this option is grayed out, it means your image already has an alpha channel.

Simple but Tedious Methods

In some cases, the following simple methods might be the best choice:

  • Rectangle Select (shortcut: R)
  • Ellipse Select (shortcut: E)
  • Free Select (shortcut: F)
  • Eraser (shortcut: Shift+E)

Using the first three tools on this list, select an area, then hit the delete key on your keyboard.

Using the eraser, first make sure the full layer is selected by pressing CTRL+A (select all). Then select the brush shape for your eraser and its size, then erase all areas you need to.

You might find yourself using some of these simple methods as finishing touches, after you've used some of the other ones to get started.

Fuzzy Select, Select by Colour, Foreground Select

In this video, watch the sections on Fuzzy Select, Select by Colour and Foreground Select to get a feel for how these work.

Find images that you think will work well with these features, and experiment with them.

If you're using PhotoShop or something else: Could you demonstrate the same of similar features in this program?

Here's one good place to download free images to use.

Your Task

Part 1

Show me three images where you have removed the background using methods of your choice.

Part 2

Quickly demonstrate to me an example of using:

  1. Either Fuzzy Select or Select by Colour
  2. Foreground Select