photoreduction
/ˌfəʊtə(ʊ)rɪˈdʌkʃn/noun
1Chemical reduction effected by light; especially a photochemical process in plant cells and microorganisms in which carbon dioxide is reduced and water is formed (rather than oxygen, as in ordinary photosynthesis).
2Photographic reduction in size.
Origin
Late 19th century. From photo- + reduction.