French artist Thomas Lamadieu, also know as Roots Art, must really love looking at the sky. Every time he looks up, Thomas sees a potential canvas where the building rooftops frame the sky. He photographs it and uses the odd sky shapes to create whimsical line drawings. “My artistic aim is to show a different perception of urban architecture and the everyday environment around us, what we can construct with a boundless imagination,” says Thomas. (Photo by Thomas Lamadieu)

This undated photograph shows one of the 14 new species of so-called dancing frogs discovered by a team headed by University of Delhi professor Sathyabhama Das Biju in the jungle mountains of southern India. The study listing the new species brings the number of known Indian dancing frogs to 24 and attempts the first near-complete taxonomic sampling of the single-genus family found exclusively in southern India's lush mountain range called the Western Ghats, which stretches 1,600 kilometers (990 miles) from the west state of Maharashtra down to the country's southern tip. (Photo by Satyabhama Das Biju/AP Photo)

Some foods have significantly more Calories than others but what does the difference actually look like. Each of the photographs below represents 200 Calories of the particular type of food; the images are sorted from low to high calorie density. When you consider that an entire plate of broccoli contains the same number of Calories as a small spoonful of peanut butter, you might think twice the next time you decide what to eat. According to the U.S. Department of Agriculture, the average adult needs to consume about 2000 – 2500 Calories to maintain their weight. In other words, you have a fixed amount of Calories to “spend” each day; based on the following pictures, which would you eat?

Jean-François Leroy launched Visa Pour l’Image, the international photojournalism festival, in Perpignan in 1989. Before heading up the festival, Leroy was shooting reportage for the agency Sipa Press and also working for Photo-Reporter, Le Photographe, Photo-Revue and Photo Magazine. He is the chairman of the company Images Evidence. Photo: 2008 Visa d'or Feature: Brent Stirton. Conservation Rangers from an Anti-Poaching unit work with locals to evacuate the bodies of four Mountain Gorrillas killed in mysterious circumstances in the park, July 24, 2007, Virunga National Park, Eastern Congo. (Photo by Brent Stirton/Exclusive by Getty Images)

While communism, collectivism, worms, dry rot and casual looting failed to destroy the majestic wooden churches of Russia, it may be ordinary neglect that finally does them in. Dwindled now to several hundred remaining examples, these glories of vernacular architecture lie scattered amid the vastness of the world’s largest country. Just over a decade ago, Richard Davies, a British architectural photographer, struck out on a mission to record the fragile and poetic structures. Austerely beautiful and haunting, “Wooden Churches: Traveling in the Russian North” (White Sea Publishing; $132) is the result. Covering thousands of miles, Mr. Davies described how he and the writer Matilda Moreton tracked down the survivors from among the thousands of onion-domed structures built after Prince Vladimir converted to Christianity in 988.

Sebastião Salgado is a Brazilian documentary photographer living in Paris. He has produced several books, and his work has been exhibited extensively around the world. His latest work, «Genesis», premieres at The Natural History Museum in London on April 11, on view through September 8, 2013. Photo: On South Georgia, a barren island in the far South Atlantic, a pair of southern elephant seal calves beckon before a colony of king penguins. “The male seals can grow to almost five tons,” says Salgado, “but these are just babies. This one looked at me with beautiful eyes”. (Photo by Sebastião Salgado/Amazonas/Contact Press Images)