Rembrandt van Rijn (1606-1669), Saskia in Bed. Photograph: Ashmolean Museum

Raphael (1483-1520), Self Portrait. Photograph: Ashmolean Museum

Leonardo da Vinci (1467-1519), A Maiden with a Unicorn. Photograph: Ashmolean Museum

Lucas van Leyden (1489/94-1533), St Jerome. Photograph: Ashmolean Museum

Thomas Gainsborough (1727-1788), Study of a Woman, Seen from the Back. Photograph: Ashmolean Museum

Ignace-Henri Fantin-Latour (1836-1904), A Woman Sewing. Photograph: Ashmolean Museum

James Mallord William Turner (1775-1851) The Transept of Tintern Abbey. Photograph: Ashmolean Museum

Raphael (1483-1520), Studies of Two Apostles for the Transfiguration. Photograph: Ashmolean Museum

Walter Sickert (1860-1942), Noctes Ambrosianae. Pastel. Photograph: Ashmolean Museum

Gwen John (1876-1939), A Seated Girl. Photograph: Ashmolean Museum

Albrecht Dürer (1471-1528), View of the Cembra Valley. Photograph: Ashmolean Museum

Antoine Watteau (1684-1721), Head of a Boy facing Right. Photograph: Ashmolean Museum

Francisco José de Goya y Lucientes (1746-1828). Two Men Fighting. Photograph: Ashmolean Museum

John Everett Millais (1829-1896), The Race Meeting. Photograph: Ashmolean Museum

William Blake (1757-1827), Beatrice and Dante in Gemini, Amid the Spheres of Flame. Photograph: Ashmolean Museum

Michelangelo Buonarroti (1475-1564), Ideal Head. Photograph: Ashmolean Museum 

Caspar David Friedrich (1774-1840), Landscape with an Obelisk. Photograph: Ashmolean Museum 

Giovanni Francesco Barbieri, known as Guercino (1591-1666), The Mystic Marriage of St Catherine. Photograph: Ashmolean Museum

François Boucher (1703-1770), The Invention of Drawing. Photograph: Ashmolean Museum 

John Robert Cozens (1752-1797), Entrance to the Valley of the Grande Chartreuse in Dauphiné. Photograph: Ashmolean Museum

Peter Paul Rubens (1577-1640), A Nude Man seen partly from behind. Photograph: Ashmolean Museum

Giambattista Piazzetta (1682-1754), Head of a Youth. Photograph: Ashmolean Museum

Pieter Bruegel the Elder (1525/30-1569), The Temptation of St Anthony. Photograph: Ashmolean Museum 

John Ruskin (1819-1900), Study of a Kingfisher. Photograph: Ashmolean Museum

Samuel Palmer (1805-1881), Self-portrait. Photograph: Ashmolean Museum