Though few moviegoers will notice it, a key scene in the Owen Wilson/Vince Vaughn comedy "The Internship" was created partially in a nondescript southwest Santa Rosa office building.

In the film, Wilson's character is supposed to be talking to another character in front of a twinkling San Francisco skyline. But during filming, the evening sky was characteristically foggy, making the background flat and grey.

Enter Factory VFX. The Santa Rosa visual effects company lightened the sky and added city lights, making the scene much more picturesque.

Company founder Eric Christensen, who served as on-set visual effects supervisor on the film, said Factory VFX digitally touched up many scenes in the movie.

"That film was the most rewarding," Christensen said. "From start to finish, that was our baby."

Christensen, 44, a Cardinal Newman and San Francisco State graduate, has carved out a niche for top-quality yet affordable visual effects in his hometown of Santa Rosa. Many Hollywood movie studios have outsourced visual effects work to India and China, he said.

"I noticed that outsourcing was becoming prevalent in this business," he said. "I figured, let's give studios a domestic resource. Our entire company is based on work gone bad overseas."

After working on more than 20 feature films as a digital artist at George Lucas' Industrial Light & Magic, Christensen left in 2006 and started RotoFactory, which services other visual effects studios. Three years later, he launched Factory VFX to work directly on movie productions.

The two companies share office space and 12 full-time employees, but can tap into a pool of talented local visual effects artists and expand to more than 30 during a project. Though most movie studios are located in Southern California, many visual effects shops are based in a Bay Area cluster known as Hollywood North.

In late 2009, Christensen moved part of the business to New Orleans, which offers better tax credits than California for film production.

"It's a bottom-line scenario," he said. "Productions will go where they can get the best value for the dollar."

Most of the work Factory VFX does is impossible to detect on the big screen. Using computer software, visual effects artists can digitally isolate characters or objects from their surroundings in a frame of film. They can be placed in new backgrounds that have been photographed separately or created on a computer.

Digital paint artists use software to create or change colors, textures, shadows or reflections in a frame of film or video. They can erase unwanted items in the background of a shot, including wires, trees, poles and film crews.

The effects are applied after a film shoot, so filmmakers can clean up or enhance the footage.

Christensen's company has worked on more than 70 feature films, television shows and commercials, including "The Kite Runner," "Fast & Furious 5," "Die Hard 5," and the recently released "Percy Jackson: Sea of Monsters."

The success of his business has allowed Christensen to pursue other local media interests. His Santa Rosa Media Institute put in an unsuccessful bid to take over the Community Media Center of the North Bay.

Christensen is starting a nonprofit to update technology in local schools. He is working with the Sonoma County Film Office to promote homegrown movie makers.

And he is working on a platform to create original movies and TV shows, which would be available exclusively online.