Although the tree-ring analysis of the Philadelphia painting firmly places it in van Eyck's workshop, the technical evidence fails to prove indisputably whether van Eyck or a workshop member painted it [REF].
There are three possibilities; the panels are van Eyck originals; they were completed by workshop members after his death from one of his underdrawings; or they were created by a highly talented follower compiling a pastiche of Eyckian motifs [REF].