Uncovering the Past, Image by Image

Michael Rierson, a Fairfax County preservationist, examines historical photographs using software that allows him to enhance the images.
Michael Rierson, a Fairfax County preservationist, examines historical photographs using software that allows him to enhance the images. (Photos By Tracy A. Woodward -- The Washington Post)
By Michael Laris
Washington Post Staff Writer
Thursday, October 18, 2007

The crusty dirt road wouldn't lie.

That was what Michael Rierson, a Fairfax County preservationist, figured when he wanted to know when the Victorian porch was torn off the front of the historic Green Spring House in Annandale.

A black-and-white photograph showed the house, with no porch, peeking out from beyond scraggly overgrowth. But Rierson was interested in the foreground.

Using sophisticated software, he began scrubbing the photo, homing in on a strip of road. "You wash it through," he said. "I enhanced and enlarged, enhanced and enlarged."

The process is a lot more complicated than on "CSI," with its smooth, beautifully lit swoosh from blurry image to crystalline money shot. But slowly, following pass after pass of the digital mop, the photograph began to provide an answer.

What Rierson got was a clear view of tire treads and the kind of thrill that has kept him working, sometimes for years, to nail down details of Fairfax County history that even he acknowledges some might fail to appreciate. "Dramatic to me means it could be boring . . . to others," Rierson said.

Some who viewed it posited that the photograph was taken in 1890, Rierson said. But pneumatic tires, and their treads, didn't show up until three decades later. That finding gave Rierson and his colleagues a fixed date to help them narrow the time frame for the loss of the porch.

Rierson has used the technique on images of historic structures from across Fairfax, searching for the tiny, telling details hidden in fuzzy backgrounds. His obsession with the precise hinge or shutter or doorknob at a particular preservation site is about much more than hardware, he said. As preservation efforts broadened throughout the country decades ago, people were sloppy, Rierson said.

"The story would go, 'You'd find a brick, and you'd build a mansion,' " he said. "People would make conclusions based on a lack of good information," and then rebuild based on incorrect assumptions or personal preferences.

Many in Rierson's generation got into preservation, in part, as a reaction to that, he said.

"If you write a bad history, that's inaccurate. That's no different than doing a bad restoration. You're forging history," Rierson said. "We wanted to do it right. . . . You're sort of trying to wash away the revisionist part of it and restore it based on facts."

Doing Rierson's brand of preservation takes archaeology, old deeds and oral histories. It also takes Rierson's "step interpolation," a process that takes scans of often small, paper photographs and augments them. That can make them crisper and allow closer-up views.

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