The German artist Gerhard Richter works in a number of mediums. As he said back in 1986, “I’m an image-maker.” One thinks of his photorealist paintings, in which his signature blurred portraits stare out of the canvas. And also of the abstract paintings, formed with a squeegee that Richter drags along wet paint, layer after layer. (He began playing with abstraction early on, in the late 1950s, with ink on paper.) And then there are Richter’s experiments with glass, which he uses to distort viewer’s perception in exhibition spaces. On the occasion of his 90th birthday, the artist himself has selected 40 works from his collection, made over the course of his life. They will be grouped thematically in his hometown. —E.C.