Emerging strategies based on the self-assembly of block copolymers have recently enabled the bottom-up fabrication of nanostructured materials with spatially distinct functional regions. Concurrently, a drive for further miniaturization in applications such as optics, electronics and diagnostic technology has led to intense interest in nanomaterials with well-defined patterns of emission colour. Using a series of fluorescent block copolymers and the crystallization-driven living self-assembly approach, we herein describe the synthesis of multicompartment micelles in which the emission of each segment can be controlled to produce colours throughout the visible spectrum. This represents a bottom-up synthetic route to objects analogous to nanoscale pixels, into which complex patterns may be written. Because of their small size and high density of encoded information, these findings could lead to the development of new materials for applications in, for example, biological diagnostics, miniaturized display technology and the preparation of encoded nanomaterials with high data density.