Hillman Curtis, a former rock musician who became a prominent first-generation Web designer and a visionary figure in the Internet’s evolution from a predominantly text-based medium to the multimedia platform it is today, died Wednesday at his home in Brooklyn, N.Y. He was 51.

The cause was colon cancer, his wife, Christina, said.

Curtis was the art director of a San Francisco software company in 1996 when he designed the first website formatted for a new technology called Flash Player, a browser plug-in that could be used to turn out high-quality animated imagery quickly. Before then the process would take hundreds of hours.

His mastery of the technology, which had been developed for several years before but never fully deployed in a way that unveiled its creative potential, made Curtis a revered figure in the emerging world of Web design.

His Flash Player design technique set the groundwork for a format that later evolved exponentially to accommodate online advertisements, Facebook applications and video sites like YouTube.

Richard Shupe, who teaches Web design at the School of Visual Arts in Manhattan, said Curtis’ Flash Player design was a milestone that “brought Web design to life.” His ability to teach other Web designers, he added, helped “jump-start a process of Web democratization that continues today.”

In 2000, Curtis published a popular how-to book, “Flash Web Design,” which sold more than 100,000 copies and remains a standard online design text. Heading his own firm, HillmanCurtis, which he started in Brooklyn in 1998, he produced Web designs for commercial clients including Yahoo, Sprint, Adobe, Rolling Stone magazine, Fox Searchlight Pictures and the Metropolitan Opera.

His mystique in the design world only deepened when, at the height of his career, he gave up Web work to learn to make movies with a handheld video camera.

For Curtis, who called himself a serial self-reinventor, it was the start of a third career. A nephew of Chris Hillman, an original member of the Byrds, he had played in a rock band in the 1980s and early ’90s before teaching himself Web design.

He was beginning to gain wider notice in his last years for his films, including a 2008 series of short documentaries about designers and artists like Milton Glaser, Paula Scher and Stefan Sagmeister, and a 2010 feature-length film, “Ride, Rise, Roar,” chronicling a concert tour by David Byrne and Brian Eno.

He once explained his penchant for reinventing himself in an interview. “I originally went to school for creative writing and film,” he said. “I then spent 10 years pursuing music, and, after failing at that, I did various random jobs. I got into design out of desperation — I didn’t want to wait tables or pound nails.”

Long after designing his last website, Curtis remained an important presence in the imagination of Web designers. And professional online journals, which referred to him as “the Michael Jordan of Web design” and “the Grandmaster of Flash,” remained fascinated by his decision to give it all up.

“It seems like you had it made,” an interviewer said recently on the Web magazine the 99%. “Why did you move on?”

Curtis answered that he had always wanted to make films and had accomplished his goals as a designer. He detailed those goals in a 2002 interview: “The reason for designing new media is simple — to subtly and quietly change the world.”