If you want to remove a background from an image, there are a few ways you can do it, and using the Background Eraser tool is one of them. This is handy for making composites, when you only need a quick cut-out to work with, tidying up the edges later on.
Mainly put to work as a quick fix for getting rid of unwanted backgrounds, the Background Eraser tool is fast, fairly accurate and does most of the hard work for you. When the background you want to delete is of a similar colouring to the part of the image you want to keep, zoom in close and sample that part of the background by Opt/Alt-clicking it. Then continue to use the tool carefully, sampling as and when you need to. The tool’s pretty clever at deleting unwanted backgrounds, and here’s how to use it.
Select the Background Eraser from the Toolbar (it may be hidden behind the Eraser). The brush size will depend on your image, but we used 100. Change the Hardness to 100%, Spacing to 25% and ensure Sampling is set to Continuous, Limits to Find Edges and Tolerance to 25%.
Click and drag your brush around the edges of the part of the image you want to keep, deleting the background as you go. The tool finds the edges itself. It samples the colour at the centre of the cursor (crosshairs) and deletes the pixels of a similar hue as you move it around.
Opt/Alt-click on the similar-coloured background then continue deleting. To finish, increase the brush size and tolerance, and delete all the surrounding background completely. You can also use the standard Eraser tool for this.