LAS VEGAS (Hollywood Reporter) - As Dreamworks Animation prepares for the May 21 release of Shrek Forever After, the studio is converting the first three movies in the hit franchise to the stereo format for a 3D Blu-ray Disc release.

Our movies exist in digital files to begin with. To go back and rebuild to a quality 3D experience is not inexpensive, but we are about to achieve a pretty high quality result, company CEO Jeffrey Katzenberg said Wednesday at the annual National Association of Broadcasters convention

He expressed optimism about the rate of technical innovation in 3D filmmaking, spending some time discussing live-action conversion -- the subject of much scrutiny since the poorly received 3D conversion of Clash of the Titans opened in theaters and prompted industry concerns that bad 3D could threaten the format's rollout.

We are just beginning to see big capital investments made into the area of post 2D-to-3D conversion. Right now it's at the most rudimentary, he said. It is going to change very, very quickly. I'm still pretty optimistic that whether it's 12 months or 18 months or 24 months from now, there is going to be a quality product in straight 2D-to-3D conversion.

Pointing out that George Lucas is looking to convert Star Wars and James Cameron, Titanic, he said, They are not going to do anything to diminish the importance of those films. Katzenberg suggested that the process could cost $20 million per film and 18 months to accomplish.

He added that he saw a test for Titanic and said: It is spectacular. Jim is a perfectionist.