Physical restoration of a painting with a digitally constructed mask

Conservation of damaged oil paintings requires manual inpainting of losses^1,2, leading to months-long treatments of considerable expense; 70% of paintings in institutional collections are locked away from public view, in part because of treatment cost^3,4. Recent advancements in digital image reconstruction have helped to envision treatment results, although without any direct means of achieving them^5-8. Here I describe the physically applied digital restoration of a painting, a highly damaged oil-on-panel attributed to the Master of the Prado Adoration from the late fifteenth century. In parallel, 5,612 losses spanning 66,205 mm² and 57,314 colours were infilled with a reversible laminate mask comprising a colour-accurate bilayer of printed pigments on polymeric films. To ensure the effectiveness of the restoration, ethical principles in painting conservation were implemented quantitatively for digital mask construction, a critically important foundation lacking in the current digital restoration literature. The infill process took 3.5 h, an estimated 66 times faster than conventional inpainting, and the result closely matched the simulation. This approach grants greatly increased foresight and flexibility to conservators, enabling the restoration of countless damaged paintings deemed unworthy of high conservation budgets.