American digital artist Casey Reas and German composer Jan St. Werner (of Mouse on Mars fame) get “Alchemical” at New York’s bitforms gallery. The show presents Reas’ experiments with machine learning techniques as image-making instruments in which he mobilized generative adversarial networks (GANs) trained on feature films. On view: a series of haunting Untitled Film Stills (2021) and five Compressed Cinema films that Werner augmented with “sentient” electroacoustic sounds.