Display Image Difference string
  
  
Description
				Specifies when to display the difference between
    images 
				Values
				
					
						
							| Value | 
							Description | 
						 
						
							| always | 
							Always display the difference  | 
						 
						
							| only-if-diff | 
							Display the difference if there is actually something
          to show | 
						 
						
							| never | 
							Never display the difference | 
						 
					
				 
			
  |