I am missing two new parameters ind getimage.aspx.
?watermark=mywatermark.png
Makes a layer of the png-file on top of the image. Useable for having to watermark images, or adding logos or borders.
?allowupsizing=1
Allows images to be scaled up. As it is now, when you process an image with smaller dimensions than the one you specify, it keeps its own dimensions. With this parameter you can allow getimage.aspx to resize the image, so it will match the dimensions you specify.