Charles-François Daubigny
Riou was born in 1833 in Saint-Servan, Ille-et-Vilaine, and studied under Charles-François Daubigny and Gustave Doré, graduating in 1859. Apart from engravings, his artistic specialties included landscape painting and commemorative art (including works for the opening of the Suez Canal and the marriage of a daughter of the Czar).