Relative difference between the m_i coefficients for estimators using two bands. The lighter shades indicate that they are fairly commensurate with one another whereas the darker shades indicate that one is much larger than the other. This happens in particular when one of the two bands does not bring additional information. This is especially common for bands that are close in wavelengths while probing similar physical components, such as the PAH or the warm dust in the MIR or the Rayleigh-Jeans tail in the FIR.