Sept. 25 (Bloomberg) -- "Walldogs" are artists who hand paint huge, photorealistic advertisements on the sides of buildings. It’s also the name of a Los Angeles-based company that paints larger-than-life ads for movies, cars and sportswear, some over 20-stories tall. Owner Riley Forsythe, a 40-year veteran of the trade, tells Bloomberg how the process works and why this low-tech method is still in demand. (Source: Bloomberg)