Phase determination algorithm reveals patches of Lo and Ld phases. Voronoi tessellation of one leaflet for (A) ρ = 0, (B) ρ = 0.5 and (C) ρ = 1 with DPPC (blue), PUPC (green), DUPC (red) and chol (yellow). Coexisting phase patches, demarcated by thick black lines, increase in size and compositional difference from ρ = 0 to ρ = 1.