Decorative concrete floors

The word concrete always sounds so dull and cold but not if you have seen the concrete floor designs by the San Francisco based Transparent House. They have come up with these very attractive designs which can be applied either while poring concrete or after it has set. I was looking for how this is done and could not find any explanation on the processes.

Related link: http://www.trendir.com/archives/001865.html
{image source: Trendir, Home Decorating Trends magazine}