Color–magnitude diagrams of K vs. J − K for observational data (left) and the Besançon models along the line of sight of NGC 6822 (right). Left panel: 227 RSG candidates are selected based on slightly modified selection criteria indicated by the K1′ and lines (221 based on rzH, 200 based on rzK, and 194 in common). The error bars at the left indicate the median error of each magnitude interval. The same selection criteria in the right panel suggest that the RSG sample is almost free from contamination of Galactic giants.