Top row: comparison of LAMOST MV with values inferred from Gaia DR2 parallax. Colors indicate the number density of stars. From left to right, panels are results for different spectral S/N bins, as marked in the plots. Bottom row: histograms of the differences, as well as Gaussian fits to the histograms. The mean and 1σ value of the differences are marked in the figure. All stars are required to have an MV error in the Gaia DR2 values smaller than 0.1 mag.