The "Tristimulus Correction Method" for modification of colorimetric data to account for a change in the color of the backing material used behind the print (e.g., black vs white) has been successfully validated since its introduction in 2005. The larger problem that has arisen is the need to adapt color characterization data for changes in paper color. The increased use of optical brightening agents and the popularity of "whiter" papers have resulted in an almost continual change in the "color" of the printing paper commonly used. Shifts of greater than 4 CIE DE2000 units between the paper used to establish color characterization data and the paper used for printing are not uncommon. It was hypothesized that a change in the backing used for measurement represented a change in paper color and was fundamentally no different than a change in the actual color of the paper. Thus backing correction was transformed to substrate correction -- the computational steps are the same, only the name has changed. This paper documents the tests conducted by CGATS and the USTAG to TC130 to validate this hypothesis. It also documents additional tests that were conducted to show the impact of the differences between the three current standard illumination conditions (M0,M1, and M2) used for viewing, colorimetric computation, and densitometric computation.