Confirm that an image has transparency | Scene7

What is an easy way to confirm that an image has transparency?

The easiest method to confirm that an image has transparency is to add a background color to it. If it is an image with transparency, you can see the background color in areas that are transparent.

Example URL structure:

http://sample.scene7.com/is/image/TestAccount/sku?fmt=png-alpha&wid=400&bgcolor=100,100,100