I just ran into this same issue. In the TweenLite section of the documentation that comes with the lib it just says this:
USAGE
The most common type of tween is a to() tween which allows you to define the destination values:
TweenLite.to(document.getElementById("photo"), 2, {width:200, height:150});
The above code will tween the width and height properties of the DOM element with an id of "photo" from whatever the current values are to 200 and 150 respectively over the course of 2 seconds. Notice the x and y values are defined inside a generic object (between curly braces). Put as many properties there as you want.
I searched the page and there's no mention of 'img' or 'image'