If you need to make a complex selection in Photoshop that involves hair or fur on a background, the powerful Refine Edge Brush is ready to help. Here’s a 1-minute Photoshop Magic Minute video by Adobe that will show you how to get started with the tool.
When your selection of a person’s hair or an animal’s fur is rough and includes the background peeking through, open up Select→Select and Mask and you’ll find the Refine Edge Brush on the left toolbar.
Using this brush, you can paint along the edge between the hair/fur and background to tell Photoshop that you want it to decide what’s subject and what’s background.
To see what you’ve brushed already, click the Show Edge checkbox to reveal where Photoshop is looking for edges (both painted in with the Refine Edge brush and the edges included by the Edge Detection feature).
Specify exactly where you’d like Photoshop to work its magic, and voila! A fine selection that isolates your subject from the background.