The Foundry makes digital visual effects software that has been used in motion pictures like Tron Legacy 3D, Avatar, Harry Potter and many others. Private equity firm The Carlyle Group just acquired a majority stake in the Foundry from Advent Venture Partners and other stakeholders. The details of the transaction have not been made public.

Making a movie involving digital visual effects is a complicated and technically sophisticated business. In fact, the visual rendering farms used for movies like Happy Feet or Lord of the Rings rank among the top 500 supercomputing centers in the world. Each film sequence combining live action and visual effects involves a huge number of visual elements that must be integrated into a final, polished product. The Foundry’s software creates rough combinations of these elements (a process called compositing) in a visual representation that can then be refined by dozens of artists. The video below shows some work created using Nuke, The Foundry’s core compositing product.

I talked to Mike Chalfen, a partner at Advent Venture Partners, The Foundry’s main investors, about the deal. He contends that this deal is a validation of the firm’s growth investment strategy. Growth investment means investing in a business that has a proven business model and technology and is usually already profitable but wants to expand. Venture capitalists tend to invest in newer products and markets.

Advent only invested in The Foundry 2 years ago. Chalfen told me that The Foundry is a typical growth equity deal. The company makes complex products which are hard to replicate and that there was a pent-up sales demand that was not being satisfied. The Foundry’s revenue more than doubled in 2010.

I asked Chalfen about the growth equity investment climate in Europe. He told me that he is feeling bullish about the tech market in Europe and that it has become less important where a company is based. According to Chalfen, in the U.S. massive tech companies are created very rapidly, but it is often easier than you think to find truly differentiated companies in Europe. However, he is of the opinion that too many European founders fall in love with their technology at the expense of the business aspect. A marriage of European technology and American business savvy could be a match made in heaven.