GHENT, Belgium — Layers and layers of paint have been virtually and physically removed from the 15th-century Ghent Altarpiece, a renowned work of biblical figures on wood panels, revealing for the first time in hundreds of years the individual brush strokes of the original paintings.

In this first phase of restoration on one of the earliest art works to use oil paints on a large scale, new scanning techniques uncovered the singular skills of the Flemish brothers Jan and Hubert Van Eyck, beneath layers of overpainting and varnish.

The restoration, which has been taking place for the last four years here at the Museum of Fine Arts, has involved painstaking work that has led to a number of discoveries, including the dating of several wooden panels from the same oak trees.

As an early Renaissance piece, the altarpiece is widely recognized as one of history’s most influential art works, because of the intimate attention it gives to both earthly and divine beauty. The polyptych altarpiece, consisting of 12 panels, has at its center its most iconic panel, “The Adoration of the Mystic Lamb.’’ It depicts a liturgy attended by different groups of people in a landscape rich in religious symbolism. In the middle is a white lamb on an altar, with a breast wound gushing blood.