A conveying apparatus for conveying an object, the object having at least a non-opaque portion, including a light source, an optical detector and a backing measurement apparatus, the light source for illuminating the object, the optical detector for acquiring information at least relating to at least one chromatic characteristic of the non-opaque portion, the backing measurement apparatus including a backing material, a backing support and a plurality of rollers, the backing material exhibiting at least one of determined chromatic characteristics and determined optical characteristics, the backing support for supporting the backing material, the plurality of rollers for rolling the backing material over the backing support, wherein light emitted by the light source optically interacts with the backing material consistently through the non-opaque portion.