CME-driven EUV waves in the simulation (left) and in the corresponding SDO/AIA observation (right). Both the simulation and observation images are produced by a tri-ratio running difference method. The tricolor channels are AIA 211 Å (red), AIA 193 Å (green), and AIA 171 Å (blue). The ratio in each channel is identically scaled to 1 ± 0.2 for both observation and simulation (from Jin et al., 2017b).