Who was the nineteenth century artist who helped elevate color lithography to a fine art?

The nineteenth-century artist who significantly elevated color lithography to a fine art was Félix Vallotton. He is known for his innovative techniques and striking use of color, which transformed the medium and influenced other artists. Vallotton's work contributed to the recognition of lithography as a legitimate form of artistic expression, beyond mere reproduction. His unique style and approach helped to establish lithography as an important art form during that period.