Photoshop CC made it very easy for users to make precise selections using the Refine Edge Tools. This is particularly important when selecting objects that would be very difficult to manually select (hair, fur, grass,etc).
Open the Select and Mask image from the source files. There are several ways to access the Select and Mask tools.
Make a loose selection around the dog. Do not select around the edges where part of the background can be seen behind the dog’s fur. You can also go to Select>Load Selection>Channel: dog selection. Use one of the options listed above to get the Select and Mask options.
Option One: Choose Select > Select And Mask.
Option Two: Key command shortcut Ctrl+Alt+R (Windows) or Cmd+Option+R (Mac).
Option Three: Choose a selection tool like the Magic Wand, Lasso, or Quick Selection. Then choose Select and Mask from the Options bar.
Change the view to Onion Skin and set the opacity to 100%. This omits anything that is not in the selection. (There are other view options that you can select to meet the needs of your project. Onion skin is a great one to start with.
Choose the Refine Edge tool from the toolbar. Drag your cursor across the edges where the fur stands out. You can toggle between views to see how the mask will apply. (You can press the K key to see the black and white mask. Press O to return to the onion skin view.)
You can continue to refine the edges until you get the appearance that you want. You can adjust the brush size the same way you would with traditional brushes. [ smaller brush, ] bigger brush.
Photoshop has several other options that you can adjust to refine your mask even more.
Edge Detection settings
Radius. Use a smaller radius for sharp edges. Use a larger one for softer edges.
Smart Radius. Allows for a variable width refinement area around the edge of your selection.
Global Refinement settings
Smooth. Reduces irregular areas
Feather. Blurs the transition between the selection and the surrounding pixels
Contrast. When increased, soft-edged transitions along the selection border become more abrupt. Typically, the Smart Radius option and refinement tools are more effective.
Shift Edge. Moves soft-edged borders inward with negative values or outward with positive ones. Shifting these borders inward can help remove unwanted background colors from selection edges.
*Decontaminate Colors. Replaces color fringes with the color of fully selected pixels nearby. This is very helpful when selecting light edges that might have a reflection such as blonde hair against a green background. The hair will have a green cast around the edge.
Output To. Determines whether the refined selection becomes a selection or mask on the current layer, or produces a new layer or document. (New layer with layer mask is suggested)
Press Ok when you have made the desired selection. You will now see a new layer with a layer mask. You can place your selected image on a new background.