Figure 2: Ankylographic reconstruction of the threonine molecule.

(a) True 3D positions of the atoms of threonine, displayed in a one-dimensional grid index. Each atom is marked by a circle coloured according to its type (carbon, nitrogen, oxygen or hydrogen), with the vertical axis marking the amplitude, which reflects the charge density in that type. (b) The reconstructed molecule using the HIO algorithm taken from ref. 10. (c) Our sparsity-based reconstruction using the GESPAR algorithm. (d) Reconstruction with HIO while enforcing sparsity in the algorithm.