function getElementsByClass(searchClass,node,tag) {
	var classElements = new Array();
	if ( node == null )
		node = document;
	if ( tag == null )
		tag = '*';
	var els = node.getElementsByTagName(tag);
	var elsLen = els.length;

	var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
	for (i = 0, j = 0; i < elsLen; i++) {
		if ( pattern.test(els[i].className) ) {
			classElements[j] = els[i];
			j++;
		}
	}
	return classElements;
}

function show_pic(picid, pic_url, text){
  var id_big_pic = document.getElementById('big_foto');
  var id_big_descr = document.getElementById('big_foto_descr');
  var id_small_pic = document.getElementById('pic'+picid);

  var obj_sel_pic = getElementsByClass('sel_preview', null, null);
    for(i=0;i<obj_sel_pic.length;i++){
		obj_sel_pic[i].className = '';
	}


  id_small_pic.className = "sel_preview";
  id_big_pic.src = pic_url+"picture-350h.jpg";

  id_big_descr.innerHTML = text;
  id_big_pic.alt = text;

}