The D50 Illuminant is the mandatory reference because it serves as the global standard (as per ISO 3664) for evaluating print samples and design specifications. Utilizing D50 establishes a common technical language between the designer and the print house, ensuring that the color data (L*a*b*) defined in the software aligns directly with the light used in the press control room.

This alignment is the foundation for accurate press calibration and the generation of precise ICC Profiles. This consistency is vital for predicting and mitigating detrimental phenomena like Metamerism, which compromises packaging color stability, and is fundamental to ensuring long-term color reproducibility in high-volume production