Towards automatic registration of technical images of works of art

As high-resolution images of paintings, acquired using various imaging modalities (e.g. X-ray, luminescence, visible and infrared reflection) become more available, it is increasingly useful to have accurate registration between them. Accurate registration allows new information to be compiled from the several multimodal images. This leads to a better understanding of how the painting was constructed and of any compositional changes that have occurred. To that end, we have produced an automatic image registration algorithm that is capable of aligning X-ray, color, and infrared images, as well as multispectral luminescence and reflectance image sets, or cubes. The key steps of the algorithm include identifying large sets of candidate control points in the reference image, then pairing them with potential points in a second image using cross-correlation. Finally, after selecting the best set of control point pairs, the second image is transformed to be in register with the reference image. Tests show the algorithm to be capable of achieving sub-pixel registration across these various image modalities.