Examples: Palm Tree on a beach | James Bond Island | Person in Forest (Using Masks)
This example demonstrates what you can do when using masks to protect or delete parts of your image.
Without protection, the person present in this image gets quite distorted when shrinking to 70% of the original dimensions (due to the high contrast of the detailed greenery that is present throughout the image). Using a mask to protect the person, and the bird she is pointing at, achieves the desired results.
You can also use masks to delete parts of your image when resizing it - this is demonstrated in the bottom-most part of the page by completely removing the person from the image.