Method and apparatus for raised material detection

摘要

A method is provided of detecting a region of raised material on a document surface. A surface of the document is illuminated with at least one angled radiation beam such that any raised material on the document surface reflects the radiation. The surface containing the raised material is imaged using at least one radiation detector. The image is then processed to detect the existence on the document surface of the raised material. The illuminating step causes a reflection and/or shadow to be generated from at least one edge of the raised material. The processing step detects the location of the material using the said reflection and/or shadow from the at least one edge.