Work backwards in Mask Pro
If you image is on a solid color background try using the apply all option with the magic brush tool. This will do 90% of the masking work in a single click. Then you can refine the mask by painting back in information that you want to save. Here is how.
Step One Open your image in Mask Pro 4
Step Two Use the drop eyedropper to select the background color. If the background is graduated try making two or three color samples one in the brightest area, one in the middle and one in the darkest area.
Step Three Double-click on the magic brush tool to apply to the entire image. This will paint away all of the background color.
Most of the time this will leave some small areas of the background or will remove some of our foreground. Use the regular brush set to remove or reveal to clean up these areas. You can check your mask quality by selecting the view mask mode by pressing 3 on your keyboard. Keep in mind this only works if your image has a solid background and the background color is not present in your foreground subject. This is great for chroma-key blue or green backgrounds.