function overImage(image)
{
  var image_src = image.src;
  var extension_index = image_src.lastIndexOf('.');
  image.src = image_src.substring(0,extension_index) + '_over' + image_src.substring(extension_index);

}

function outImage(image)
{
	var image_src = image.src;
  	var extension_index = image_src.lastIndexOf('.');
  	image.src = image_src.replace('_over\.','\.');

}