Now, Pike drivers get the big picture

Yesterday, it featured succulents - six inoffensive close-ups of cacti and yucca. Today, the lineup calls for colorful paintings by the Mexican muralist José Orozco. Sunday, it will be photos of the Japanese attack on Pearl Harbor.

WGBH activated a three-story screen this week that can display shifting images from its headquarters on the south side of the Massachusetts Turnpike in Brighton, giving thousands of drivers their first glimpse of what the station hopes will become a landmark, on par with the Citgo sign and the gas tank painted by Sister Corita Kent.

Every day, from 6:30 a.m. to 7 p.m., the screen will feature a changing display of about a half-dozen images on a specific theme - Curious George, the Boston Symphony Orchestra, clouds wafting atop a Hawaiian crater. The still photos, beamed out by energy-efficient LED technology, will change every 30 seconds under guidelines established by the city and community groups, with the whole loop repeating every three minutes or so.

But the screen, which WGBH calls a digital mural, is forcing the public radio and television station to walk a fine line between promotion and education with the photos it displays, and to weigh concerns about safety for the 500,000 eastbound drivers who will pass it every week. Images of the station's hosts are out (too promotional). So is anything risqué (poor taste), anything with text (potentially distracting), and anything with a narrative arc - such as a lion chasing a gazelle, which might draw motorists' attention for too long.

The screen is the first of its kind to be licensed in Boston, and officials acknowledged it is an experimental venture for the Hub, introducing a flavor more common in venues such as Times Square and Las Vegas. Boston officials and WGBH want this incarnation to be distinctly different, more subtle and placid without being boring.

"In the best possible sense, we hope it's a gift to the city and not a blight on the landscape," said Christopher Pullman, vice president for branding and visual communications at WGBH.

Some commuters who speed by on the Turnpike every day welcomed the 30-by-45-foot screen as a pleasant diversion in an otherwise drab cityscape. Others worried that a display of celebrated paintings, seminal historic events, or world landmarks is bound to cause an accident.

"It's just another distraction you don't need on the road," said Craig Tiedemann, a lawyer who drives the Pike every day from Brighton to his office downtown. "You've got people changing their DVD players in their cars and on their phones and now we've got to look at this slide show? I think it's a risk."

But Charlie Vasiliades, who saw the cacti yesterday morning on his daily bus ride from Brighton into downtown Boston, was impressed.

"It's really very elegant," said Vasiliades, who works for the state Department of Housing and Community Development. "It's nice to have something new and fresh. I think it's an attraction and I like it."

WGBH proposed the screen to the Boston Redevelopment Authority three years ago as part of its plans for a new state-of-the-art headquarters on Market Street. Pullman said the station wanted to take advantage of its location on the highway to raise its profile without offending drivers or violating WGBH's civic-minded tradition.

In meetings with the BRA and Allston-Brighton residents, WGBH agreed on a series of limits. No video. The images must change slowly, like a slide show. After 7 p.m., a "screensaver" must be displayed (WGBH has chosen a "tranquil image of the evening sky over Boston as seen from the west"). No product advertising. And the station's call letters may accompany the photos for only 2 1/2 hours in the morning and 90 minutes in the afternoon.

"It gave us a comfort level to know that, with those parameters, it really cannot go completely wrong," said Prataap Patrose, the BRA's director of urban design. "It was not about hitting you over the head with what the image of the day was. It was much subtler."

Each image is inspired by PBS programming. The succulents evoke the Victory Garden, for example, and the photos of Pearl Harbor are from the Ken Burns documentary on World War II. Monday at 11 a.m., the screen went live with an image of leaping dancers from Dayton Contemporary Dance Company, part of the show "Great Performances."

"It's covertly promotional, in the sense that we do hope people understand who is in the building and what they do," Pullman said, "but we're not trying to sell them anything."

Now, WGBH is soliciting more ideas from the public for future displays. About 350 people responded to an online poll, suggesting images as diverse as children starving in Darfur and the view of outer space from the Hubble Space Telescope. WGBH and local officials hope drivers will look forward to seeing what images are chosen every morning.

"I would say it has the capacity to become a major landmark for Allston-Brighton," said Representative Kevin G. Honan, who represents the neighborhood. "It's definitely eye-catching. You can't miss it. And you'll certainly know you're entering Allston-Brighton."

Michael Levenson can be reached at mlevenson@globe.com.