  In this work, we use the spectroscopy-based stellar color regression (SCR)
method with ~ 0.7 million common stars between LAMOST DR7 and Gaia EDR3 to
acquire color corrections in G - GRP and GBP - GRP. A sub-mmag precision is
achieved. Our results demonstrate that improvements in the calibration process
of the EDR3 have removed the color term in GBP - GRP and eliminated the
discontinuity caused by the changes of instrument configurations to a great
extent. However, modest systematic trends with G magnitude are still detected.
The corresponding color correction terms as a function of G are provided for
9.5 < G < 17.5 mag and compared with other determinations. We conclude that the
corrections given in this work are particularly suited for cases where the
color-color investigations are required while for color-magnitude
investigations other corrections may be better due to systematic with
reddening. Possible applications of our results are discussed.
