I have a large image to be use as a background-image of a page. What I want is that the height of the image will be stretched to fill the height of the page. It
background-image
background-size: cover will do the trick in modern browsers - see mozilla's documentation for more details.
background-size: cover
For older browsers (particularly older versions of IE), I've had a lot of success with jQuery plugins like this one to emulate the behaviour.