 UMETSAT is developing the ground processing chain for the infrared sounder, IRS, sensors on board the MediaSAT third generation sounding satellite, MTGS. To assess the impact of calibration ringing, a type of radiometric error, the authors simulated it in the context of the MTGS IRS sensor in the LWIR band. They use the principal components, PCs, decomposition to design a software correction, called RTF Uniformization, which they tested in the context of the MTGS IRS. This article was authored by Pierre Dussarat, Guillaume Deschamps, Bertrand Theodore, and others.