An unknown self-portrait of Vincent van Gogh was discovered under cardboard and glue on the back of another painting.
Restorers at the National Galleries of Scotland said the image was found in an X-ray taken while they were examining another painting in preparation for the exhibition.
Experts say Van Gogh often reused canvases to save money. A self-portrait is hidden on the back of the head of the Head of a Peasant Woman, 1880s.
It may be possible to discover a hidden self-portrait, but the process of removing glue and cardboard will require delicate conservation.