The backgrounds in SharePoint 2010 were designed to allow end users to change gradients by simply picking solid colors on the settings page. For example if you choose an orange background color the result is a fade from orange to lighter orange. The change can be very subtle but is an effective way to create an attractive site. This is a significant upgrade from older versions of SharePoint where, in order to change the branding, you would have had  to undertake the time-consuming task of editing all of the gradient images one by one.

This branding technique is accomplished with the use of transparent PNG images. The images do not contain the color information only the blend and are mostly transparent so any color can show through. The end result is a blend from light to dark in any color that is chosen.

The illustration below shows the “Felt” color palette on the left and the “Viewpoint” color palette on the right. In the middle is what the gradients would look like if all of the background colors were black.