Any of various techniques based on fluorescence in situ hybridization (FISH) that uses a palette of fluorescently labelled probes to identify specific chromosomes or chromosomal regions by ‘painting’ them in different colours. It is used diagnostically in clinical cytogenetics to screen for translocations or other structural aberrations, for example in hereditary diseases and cancer, and in comparative cytogenetics to determine the structural changes in genomes occurring during evolution. See spectral karyotyping.