Crowdsourcing Verified Double Lightning Strike Photo
I was walking past the Trump Tower in downtown Chicago on Saturday with Adrian Holovaty when he described a photo shot earlier that week of two lightning bolts simultaneously striking the spires of two buildings. Chicago and much of the Midwest had been rocked by thunderstorms for several days in a row last week, and the image seemed to capture the spectacular force of the storms.
Holovaty had not finished describing the image before I blurted out, "I wonder if it was real?" He didn't mention that the photo was taken by a Chicago Tribune photographer; I assumed it was an amateur.
Apparently I'm not the only one who asked that question.
The photo, captured by photographer Chris Sweda, traveled the world over. The first reaction for a lot of viewers was skepticism -- so much so that the Chicago Tribune added a postscript on its blog explaining how they concluded that the photo accurately portrayed what had happened. NPR noted the newspaper's explanation as well.
"It's the online persona to challenge and question events, and that is not totally a bad thing," said Torry Bruno, the Tribune's associate managing editor for photography, who noted, "Never in my entire career has an image gotten such attention and created this kind of buzz so quickly."
Holovaty, programmer as well as a journalist (and a member of Poynter's National Advisory Board), told me he looks to the Hacker Factor blog for items tagged image analysis for the latest on sleuthing out doctored photos. Hacker Factor author Neal Krawetz offers great insight on how various tools and filters reveal doctored photos.
But none of those sleuthing techniques would have helped Tribune photo editors, who were looking for a more subtle form of manipulation. They wanted to determine if Sweda's exposure time of four seconds made two nearby lightning strikes seem as if they had occurred at the same time.
For the answer to that question, they turned to the crowd, comparing Sweda's photo to other photos and a video of the Chicago skyline from that night. Indeed, they found enough similar documentation to be fairly certain the photo accurately reflected the spectacular phenomenon.
Ultimately they found three pieces of corroborating evidence. A Tribune photographer in another location took a similar photo of the lightning bolts, using a much shorter exposure. The internal clocks of both cameras time-stamped the photos at 7:45 p.m. And an amateur video also documented the double strike.
Between the four-second and 1/80-second exposures, editors saw the same thing. The camera is able to capture what the human eye cannot. "It's totally authentic," Bruno said. "We confirmed the veracity of the photograph" by the work of a staff photographer and a video posted to the Internet. "The image is real!"
Images cross back and forth between the Fourth and Fifth Estate as fast as ideas. Spectacular amateur photos and video become fodder for news. Great news photos end up on blogs. (Copyright violations on these images is a matter for another post.)
As photos and videos of dramatic and popular events become ubiquitous, it will become easier and more important to detect frauds.
For the Fourth Estate, verifying that a photo is authentic is a matter of credibility. Krawetz recounts his efforts to help National Geographic and Smithsonian spot user-submitted fakes. Editors need training to know what tools to use and how to use them. Sometimes, they'll need the help of the Fifth Estate.
Verification is critical. In order to be thorough, the Fourth and Fifth Estates will naturally develop methods of complementing each other on this task, to promote a common good. That's reassuring. If the reaction to every cool image were doubt, people would stop reacting.