In Your
<Window.Resources>
//Create Two StoryBoard & give them x:key namely ImageEnterKey & otherOne ImageExitKey
</Window.Resources>
then later in code Behind on Your ImageEnterEvent write this code:
this.BeginStoryboard(FindResource("ImageEnterKey ") as Storyboard);
& in code Behind on Your ImageExitEvent write this code:
this.BeginStoryboard(FindResource("ImageExitKey") as Storyboard);