1. In printing a document job, the document job including placing images on a surface, a method of measuring a bare surface signature of the surface within a print engine including the steps of: defining image colorant free zones on the surface, including the step of responding to the content of images and the location of zones between images to identify image colorant free zones, determining the locations of the image colorant free zones along the surface, including the step of treating the image colorant free zones of the surface as bare surface zones, providing image colorant density signals along the surface with said images placed, extracting the image colorant density signals of the image colorant free zones along the surface according to the locations, and providing the bare belt signature of the image colorant free zones in response to the extracted image colorant density signals of the image colorant free zones.