function roundalize (pool,dias,feld,imagedir) {
	images=new Array();
	
	// list available images
	for (i=1;i<=pool;i++){
		// generate filenames
		fn="0000"+i;
		fn=fn.substr(fn.length-2);
		file=imagedir+fn+".jpg";
		// place on array
		images[i-1]=file;
	};

	// loop placeholders
	for (p=1;p<=dias;p++){
		
		// get random image
		num=Math.floor(Math.random()*images.length);
		
		// show image
		document.getElementById(feld+p).src=images[num];
		
		//remove image from list
		a=images.slice(0,num);
		b=images.slice(num+1,images.length);
		images=a.concat(b);
	};
};