That is they retain their size. So when I applied a mask it would retain it's size when applied to a much larger image. Then I could move the mask around and place it where I wanted. This next example uses a subtle but very interesting idea, you can create masks just using selections which contain no color. The background of the selection is considered fully opaque, i.e. will be fully transparent when used.
Lets take a look at a simple example using a faded edge mask.
Step by Step Example of the View Mask Example of the Edited Mask Creating the Mask Open a New Image. You can use any size square or rectangle. Using the Selection Tool with the feather set to 0 and antialias selected, draw a rounded square starting at 25 and ending at 175. It helps to turn the ruler on. You can use a larger or smaller radius.