Fig. 5From: The dark halo technique in the oeuvre of Michael Sweerts and other Flemish and Dutch baroque painters. A 17th c. empirical solution to mitigate the optical ‘simultaneous contrast’ effect?A Anthony Van Dyck, Portrait of Lord John Stuart and his Brother Lord Bernard Stuart, c. 1638. Oil on canvas, 237.5 × 146.1 cm. National Gallery (London), inv.no. NG6518. The white rectangle indicates the detail area shown in B and C. Permission to use image pending. B Detail of Lord Bernard Stuart. C Matching detail of the infrared photograph showing a dark halo along the head of Lord Bernard Stuart. Images courtesy of the National Gallery LondonBack to article page