Remove previous dates from jQuery UI calendar

How to disab开发者_JAVA百科le the previous dates in jquery ui calendar.

Also how to set the calendar popup from image, rather than direct from the text box

$( ".selector" ).datepicker({
  minDate: new Date(2007, 1 - 1, 1), //this sets the date before which no dates will be available
  showOn: 'button', //this makes it so the callender only pops up when you click the button
  buttonImage: "images/calendar.gif", //sets the button image
  buttonImageOnly: true //use an image instead of a button
});

Next time just read the documentation http://jqueryui.com/demos/datepicker/