Scatter plot with pixel values of TYPE 1 CO map as abscissa and pixel values of TYPE 2 CO maps as ordinate. We smooth all maps to 30 arcmin resolution and increase the HEALPix pixel size to N_side = 256 for this figure. The top figure shows the scatter for CO J = 1 → 0 Planck maps, and the bottom figure shows it for CO J = 2 → 1 maps. For large signals, the signal in TYPE 2 maps is higher than in TYPE 1 maps for the J = 1 → 0 line, and lower for the J = 2 → 1 line. In the inset window, we show that the low-brightness pixels do not show obvious inconsistency. This is in agreement with the comparison made in Planck Collaboration XIII (2014).