The use of the 1939 standard colorimetric observer for modern display calibration and color management has proven to be problematic in that it doesn’t adequately predict the color matching of actual human observers. Recent research has resulted in the ability to identify physiologically based Cone Fundamental (CF) curves that more accurately predict individual color matching. However, the challenge still remains of adapting CF curves for the use of imagery and color specification based on the 2-degree 1931 standard observer. The use of iccMAX-based color management requires well defined relationships between custom observers and the 2-degree 1931 standard observer to be provided. In this paper, mathematical relationships and principles between cone fundamentals and color matching functions relative to viewing primary lights are outlined. Methods of conversion between cone fundamentals and color matching functions are explored and compared along with the proposed use of Wpt based material adjustment transforms to create color matching functions that provide backwards compatibility with legacy standard observer colorimetry.