window.onload=function(){
	var maxwidth_prod_thumb = 180;
	var maxheight_prod_thumb = 160;
	
	var maxwidth_prod_img = 200;
	var maxheight_prod_img = 300;
	
	var ratePImg = maxheight_prod_img / maxwidth_prod_img;
	var ratePThumb = maxheight_prod_thumb / maxwidth_prod_thumb;
		
	var imgs = document.getElementsByTagName("img");
	
	for(var i = 0; i < imgs.length; i++) {
		// for class name = prod_img
		if(imgs[i].className == "prod_img") { 
			var imgwidth = imgs[i].width;
			var imgheight = imgs[i].height;
			
			if (imgheight / imgwidth < ratePImg){
				imgs[i].width = maxwidth_prod_img;
			} else {
				imgs[i].height = maxheight_prod_img;
			}
		}
		// for class name = prod_thumb
		if(imgs[i].className == "prod_thumb") { 
			var imgwidth = imgs[i].width;
			var imgheight = imgs[i].height;
			
			if (imgheight / imgwidth < ratePThumb){
				imgs[i].width = maxwidth_prod_img;
			} else {
				imgs[i].height = maxheight_prod_img;
			}
		}
	}
}