The Extract command in Photoshop enables us to isolate a foreground object
from its background.
Open an image you would like to extract the background from. I choose this
image of a dog. You can use my image if you like. To save it, Right Click
and choose "Save As" to download.
After you have loaded an image, go to Image>Extract. You’ll see the same image
come up in the Extract window.
The first thing we’ll need to do is outline our foreground object, in this case
of course the dog. Select the Edge Highlighter tool (as shown).
Now set a brush size and outline your foreground object. Zoom in if needed:
Select the Zoom tool, click on the image to zoom inward.
Now we need to fill our foreground object by using the Fill Tool.
Select the tool and click in the center of the object.
Now we are ready to preview the image by pressing the "Preview" button at the top
right corner of the window. You now should see the background disappear.
Under the Preview Options you can change the background color if needed.
If you like what you see, then press the OK button.
Sometimes it’s not always perfect and you may need to clean up some edges with
the Eraser Tool. If this is the case, then click on OK, now select the Eraser
and clean up the edges.
Here's my final image. I inserted a different background that could match the image.