LUX is a heterogeneous MIMD parallel computer dedicated to ray tracing and related algorithms. This system is designed to reduce nowadays rendering time by a factor of about one hundred, compared to a single general purpose processor, with a reduced chip-set. The grain of parallelism and degree of specialization both fit the tree describing the scene. Processing units are dedicated to leaves or nodes of this tree, with specialized data paths, allowing very high computational power. Moreover, the system provides low level mechanisms to manage specialization, parallelism and load balancing strategies. Those mechanisms allow flexibility and easy design of programs.