Computed, not painted. Each pixel follows a ray of light backward through the curved spacetime of a non-spinning black hole (the Schwarzschild solution of general relativity) until it falls in, hits the disk, or escapes to the stars. The disk's brightness includes gravitational redshift and Doppler beaming. Simplifications: a thin disk, no spin (so no ergosphere and no jets, which need spin and magnetic fields), and colors scaled to visible light; real disks around stellar black holes glow mostly in X-rays.