Left: 3D contact maps of chromosome 20 (top) and the long arm of chromosome 14 (bottom). Each pixel represents all contact between a pair of megabases (1 megabase = one million letters) of the human genome. The more intense the pixel, the more frequently the regions tend to be in contact, suggesting that they are nearer to one another. The bright blue dot in both maps is the centromere; unmappable regions are shown in grey.
Right: Correlation maps of chromosome 20 (top) and the long arm of chromosome 14(bottom).
The checkerboard structure in these maps reveals the active and inactive compartments of the human genome.