function changeImg(mypic, xw, xl){     
         
	//alert(mypic);
	
	var image=new Image();
    image.src=mypic.src;

    var width = image.width; 
    var height = image.height; 		
	
    var bili = width/height;                  
		 
    var A=xw/width; 
    var B=xl/height; 
         
    if(A<1||B<1) 
    { 
        if(A<B) 
        { 
			//alert("1")
            mypic.width=xw; 
            mypic.height=xw/bili; 
        } 
        if(A>B) 
        { 
			//alert("2")
            mypic.width=xl*bili; 
            mypic.height=xl; 
        } 	
		if(A==B){
			//alert("3")
			mypic.width=xw;
			mypic.height=xl;
		}	
    } 		
	
	//alert(xw + "," + xl)
}