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Visualizing pentimenti : revealing the hidden history of paintings

Art conservators often explore X-ray images of paintings to help find pentimenti, the artist's revisions hidden beneath the painting's visible first surfaces. X-ray interpretation is difficult because framing, canvas damage, and noise clutter the image; because X-rays superimpose features from all paint layers, and because image intensity depends on both the paint layer thickness and each pigment's opacity. We present a robust user-guided method to suppress clutter, find visually significant differences between X-ray images and colour photographs, and visualize them together. These tools allow domain experts as well as museum visitors to explore the artist's creative decisions that led to a masterpiece.