It’s never been harder to distinguish between commercial and art photography. Today’s advertisers are aces at co-opting the best aesthetic tricks, while photographers use massive formats, image-editing software and light boxes. The annual Contact photography festival gives this mash-up legs with its city-wide public art installations, which take over normally corporate domains—subway stations, transit shelters and billboards—for the month of May. This edition’s participants include celebrated Vancouverites Rodney Graham and Rebecca Belmore, as well as local shutterbug Eamon MacMahon, whose pan-Canadian views of devastatingly beautiful and just plain devastating environmental phenomena grace a kilometre of moving sidewalk at Pearson airport. When it comes to this kind of art, it’s all about the double take: the installations may not look much different from ads, but they demand far more than a passing glance.

Contact 2008. May 1 to 31. Prices vary. Toronto Pearson International Airport, 3111 Convair Dr.; plus various other locations, 416-539-9595, www.contactphoto.com.