Hello former colleagues ... ;)
When resizing an image proportionally to a specific width and height, lets say 685 x 456, you might end up with an image that's smaller than
685 x 456 because of the proportions.
But the imagehandler still creates an image that fits
685 x 456 but the 'extra' part of the image is just plain white. Look at this example: http://bit.ly/bLFYCX
My suggestion goes on creating another parameter called bgcolor where I could write the hex value for the wanted background color.