ARTIST: Giovanni Bellini (c.1435-1516), the most brilliant of a family of painters who dominated Venetian and northern Italian art in the late 15th century, including his father Jacopo, brother Gentile and brother-in-law Mantegna. Gentile travelled through Venice''s eastern empire visiting the Ottoman court; Giovanni was more homebound and is credited with popularising portraiture in Venice. ''He introduced into Venice the fashion that everyone of a certain rank should have his portrait painted either by him or by some other master,'' wrote the 16th-century art chronicler Vasari. SUBJECT: Leonardo Loredan (1436-1521) in his official costume as Doge of Venice, the Venetian Republic''s head of state, elected for life by a college of male nobles. Distinguishing features: This painting puts Loredan before us, separated only by the stone ledge he stands behind, yet at the same time he is located in a magic realm of perfect blue sky. It is an astonishing exercise in three-dimensional modelling. Bellini has made this painting as solid and deep in space as the Roman portrait busts that Renaissance artists emulated. You feel you could walk around Loredan, and put your hand between the folds of his clothes. This is what all Renaissance artists wanted to achieve, but what Bellini does with perspec-tive is exceptional. These Roman portrait busts were hard, public images of authority. Early Italian Renaissance portraits of powerful men and women had similar qualities. Loredan, behind his ledge, is as static as a marble bust. Yet he is softened by the tenderness with which Bellini renders his flesh, and the delicacy of his garments. Bellini was the definitive Venetian master of colour, reflecting the rich tones in the canals of the city and the fluid Venetian light. Loredan''s face glows with the gold evening sun. His skin looks mellow, its age showing not as decay, but as a muting of harsh lines. And his clothes! Loredan was known as a...