Color-magnitude diagram (top panel) and linear dependence between color excess E (J − K_s) (lower panel) versus the difference of mean intensity and absolute magnitudes. In the top panel, we plot all sample stars. The red lines denote conditions listed in Table 2 for the selection of bulge RR Lyrae sub-sample. In the bottom panel, the black dots represent selected stars from our sample, blue lines represent the reddening vector, and red circles depict individual bins.