BackgroundColor
Changes the background color of the current image. This functionality is useful for adding a background when resizing image formats without an alpha channel.
Requests are passed thus:
<!--Hex-->
http://your-image?bgcolor=800080
<!--RGBA-->
http://your-image?bgcolor=128,0,128,255
<!--Known Color-->
http://your-image?bgcolor=purple
Examples
Original

Purple Background Color
