Rescaling images with decker

Is there a possibility to rescale images with decker both in width and heigth? The only thing I could find regarding this issue was in the "For Developers" section of the Decker Wiki, there it says: "There are only two attributes that can be used to control media element size, width and height. Either width or height can be used, but not both at the same time". Is there any workaround to this issue, because it is really impractical when working with a lot of images to always having to screenshot them in the correct size for where they are supposed to go in the presentation.

With best regards, Tim Gröppel