Especially product images usually "suffer" from this issue; the product itself is composited on a white background and there are large areas of white around the object.

This is a simple example to demonstrate how to easily trim the areas off the image and only display the parts where the object lies.

His example code, a quick 16 line affair, takes in the test image, looks for a RGB value given and uses the built-in trimImage function to reduce its size.