One of the most technically groundbreaking blockbuster movies of all time was James Cameron's 1991 sequel, Terminator 2: Judgment Day. Cameron, who wrote and directed the film, had come off the back of the similarly challenging The Abyss, a movie that itself boasted a breakthrough moment in visual effects.

But for Terminator 2, Cameron set a new bar for creating and utilizing technology. For the film to work, he needed a computer-generated villain, the relentless T-1000. Played in human form by Robert Patrick, the T-1000 could morph into other shapes and take on a liquid metal form. It was a staggering breakthrough. As visual effects magician Dennis Muren would note, "it wasn't like you couldn't have done this two years ago. It was more like you couldn't have done this a week ago."

Muren was effects supervisor on The Abyss as part of the team at renowned visual effects specialists Industrial Light & Magic. He took on a similar role with Terminator 2, but he and his colleagues soon hit a big problem.

It came at a moment where the T-1000 was required to stretch into certain poses. The stretching was causing mayhem, and the visuals being rendered on the screen weren't working. "Giant black gashes appeared in his shoulders," Rebecca Keegan wrote in her book The Futurist: The Life and Films of James Cameron. "The movements were ripping up geometry."

ILM called in lots of people to help, with scientists dropping in to the company's offices to try and grapple with the mathematical challenges facing them. But a major breakthrough finally occurred when an ILM employee in his 20s, John Knoll, joined forces with his brother Thomas, a University of Michigan PhD student.

They had come up with a new piece of software that could edit the necessary graphics and, they hoped, resolve the problem. That's just what the software would go on to do, and when James Cameron saw the in-progress development of the T-1000, he finally dared to think that his imagined villain might actually work.

The name of the software? That'd be Photoshop, the very first version of the now industry-standard graphics and photo editing software.

Following the release of T2, John Knoll stayed with ILM rather than following Photoshop to its now-publisher, Adobe, and he's now chief creative officer at the firm. Thomas Knoll remained as lead developer on Photoshop until 2008, when he moved over to work on camera plug-ins for the program.

Terminator 2: Judgment Day, meanwhile, would gross over $500 million at the global box office (still the most for any Terminator movie) and take home an Oscar for its pioneering visual effects work.