function picresize(obj,MaxWidth,MaxHeight){
	if(!window.XMLHttpRequest) //仅IE6执行
	{
		obj.onload=null;
		img=new Image();
		img.src=obj.src;
		if (img.width>MaxWidth && img.height>MaxHeight){
			if (img.width/img.height>MaxWidth/MaxHeight) {
				obj.height=MaxWidth*img.height/img.width;
				obj.width=MaxWidth;
			}else {
				obj.width=MaxHeight*img.width/img.height;
				obj.height=MaxHeight;
			}
		}else if (img.width>MaxWidth) {
			obj.height=MaxWidth*img.height/img.width;
			obj.width=MaxWidth;
		}else if (img.height>MaxHeight) {
			obj.width=MaxHeight*img.width/img.height;
			obj.height=MaxHeight;
		}else{
			obj.width=img.width;
			obj.height=img.height;
		}
	}
}