Robert H. Johnston, an archaeologist and teacher who combined his interest in ancient texts with digital imaging technology to help uncover new information about the Dead Sea Scrolls and other rare documents, died Oct. 19 at his home in Rochester, N.Y. He was 77.

Mr. Johnston had suffered a series of health problems, including several infections and a stroke, said his wife, Louise.

Mr. Johnston, a longtime faculty member of the Rochester Institute of Technology, first brought antiquities and digital technology together in the early 1990s when he was acting director of the school's imaging science center. He and several colleagues began to analyze photographs of the Dead Sea Scrolls, which date from about the time of Jesus, hoping to uncover new data.

"Bob was a pioneer," said Bruce Zuckerman, director of the West Semitic Research Project at the University of Southern California. "He built a bridge between technical enhancement and the humanities."

Zuckerman supplied Mr. Johnston with photographs of the so-called Temple Scroll, one of the most important in the collection. At 28 feet long, it is the largest of the scrolls, and its text describes an ideal Jewish temple.

Mr. Johnston and his team, which included Roger L. Easton, an imaging scientist on the school faculty, and others from Eastman Kodak Co. and the Xerox Corp., found 18 Hebrew letters on the Temple Scroll.

"That might not sound like a lot, but whole matters of history can turn on a single, specific letter," Zuckerman said.

Mr. Johnston and his team made other breakthroughs when they examined a 10th-century copy of a treatise by Archimedes, the Greek mathematician who died in 212 B.C.

Once the first several pages of the Archimedes text had been analyzed, they were displayed in 1999 at the Walters Art Museum in Baltimore to show what digital technology had revealed.

"The process they developed is unprecedented," said Richard Leson of the museum's Department of Manuscripts and Rare Books. Earlier, Leson said, "we had references to the Archimedes text, but we didn't have access."

Mr. Johnston was born in Redding, Pa., and graduated from Kutztown University in Pennsylvania before receiving a master's degree in fine arts at Columbia University and a doctorate at Pennsylvania State University.

He worked in academia before joining the faculty of Rochester Institute of Technology in 1970. He was dean of the school's College of Fine and Applied Arts for 22 years and acting director of the science imaging center for two years. He retired in 1994 and was named a dean emeritus. He was active on the campus until about a year ago.

Along with his wife, he is survived by two daughters and four grandchildren.