Open-source digital image correlation application for monitoring humidity-induced deformation in canvas paintings with metrological evaluation

An open-source MATLAB-based Digital Image Correlation (DIC) software package, Ncorr, was applied to characterise the deformation response of hygroscopic canvas during desiccation following exposure to elevated temperature and relative humidity. Results demonstrate that this workflow quantitatively captures full-field deformation of stretched canvas during drying. Pronounced shrinkage occurred along the frame, with additional central contraction, reflecting the influence of the wooden stretcher combined with moisture loss. Orientation-dependent strain patterns further reveal complex deformation behaviour. Metrological evaluation confirms the methodological reliability of the approach and sufficient sensitivity to detect subtle mechanical responses below reported conservation concern thresholds. The method provides a cost-effective tool for assessing mechanical behaviour and identifying areas of potential vulnerability in hygroscopic materials under environmental change.