Color−magnitude and color−color diagrams for both the Orion A and the CF data. The colors indicate normalized source density within a 0.1 × 0.1 mag box in the J vs. J−K_S parameter space and 0.02 × 0.02 mag in J−H vs. H−K_S. The black arrows indicate the effect of an extinction of 1 mag in K_S. The presence of heavy dust extinction in Orion A pushes many sources toward redder colors when compared to the CF, which itself has a clearly defined main-sequence (0.2 ≲ J−K_S ≲ 1.2, 0 ≲ H−K_S ≲ 0.4) and galaxy locus (1.2 ≲ J−K_S ≲ 2.2, 0.5 ≲ H−K_S ≲ 1.2) in both diagrams.