Paul Simon never wrote a song about Kodak Ektachrome, so you’ve probably never heard of it. But you have seen pictures shot on the film: The astronauts brought it to the moon in 1969, and National Geographic photographers have carried it around the globe.Launched in 1946, Ektachrome evolved from a slightly finicky stock prone to issues with fading into a go-to medium valued for its vibrant colors. Hues skew toward the blue end of the spectrum, creating more-realistic images than the warmer Kodachrome of Simon fame. Both are slide films—meaning they produce full-color pictures right on the film rather than white-is-black/black-is-white negatives. But Ektachrome is easier to handle: While Kodachrome gets its color from dyes in the developing process, Ektachrome contains its own pigments, so developing is less labor-intensive.But the film favorite nearly didn’t survive a tumultuous decade. As digital cameras and smartphones axed analog photography’s market by 80 percent, Kodak ended Ektachrome’s run in 2012. The sunset, however, did not last long. Since 2015, a growing enthusiast market and a goose from cinematic heavies such as directors J.J. Abrams and Christopher Nolan have helped 35-millimeter-film sales rebound. The trend spurred Kodak to revive Ektachrome.Over the past three years, the Rochester, New York, company has worked to fine-tune the chemical mix that made the iconic film, which is on sale now in all of the most popular formats. Here’s a look at how thin strips of acetate become tiny blank canvases.