A new European collaborative research project IST-2000-28008, ‘Veridical Imaging of Transmissive and Reflective Artefacts’ (VITRA), has the objective to facilitate the capture of digital heritage images in historic buildings, enabling the acquisition of high quality colorimetric images of stained glass windows (SGW). One of the image processing problems that must be addressed is the mosaicing of multiple sections of a single SGW to produce a single large image. Mosaicing of SGW presents several challenges in terms of image processing. One of these is the necessity of a uniform illumination across the different parts comprising the mosaic. The observed variations are poorly compensated by global equalisation algorithms. In this paper we suggest a local approach to the problem that exploits the geometrical structure of SGW.