Its important to understand that the boolean flag : $FIT is used as a MAXIMUM boundary of either X or Y
If you use a physical image with a size of 128x256
 
 scaleImage(200, 100, true);  Will scale Y to 100 and X will be calculated
 scaleImage(100, 120, true);  Will scale X to 100 and Y will be calculated
$FIT is a LIMITER which is why it requires both an X and a Y for $FIT=true