function generate_image2()
 {
  var obrazek = Math.ceil(Math.random() * 10);
  document.getElementById("MainImage").style.backgroundImage = "url(./images/main/main_" + obrazek + ".jpg)";
}

function generateImage(obrazky)
 {

	setInterval("nahodneCislo = Math.floor(Math.random() * (10) + 1);document.getElementById('MainImage').style.backgroundImage = 'url(' + obrazky[nahodneCislo-1] + ')';",3000);

}