Optical scatter correction for film scanners

Abstract

A film scanner of the type which uses diffuse illumination and an array sensor such as a line array or area array CCD includes an integrating optical element in the form of an integrating sphere to provide diffuse illumination to film. The diffuse illumination ensures that light is provided to film at a range of angles thereby improving the light level reaching the array sensor from film that has been scattered by defects such as scratches thereby reducing the visibility of such defects. A lens is provided at the exit aperture of the integrating sphere so as to define a particular area of the surface within the integrating sphere from which light that is not scattered by film is derived. The area has a lower reflectivity than the remainder of the integrating sphere thereby increasing the amount of light derived from scratches that reaches the sensor to further reduce the visibility of scratches. An additional light source can also be provided at the area of the integrating sphere so as to increase the visibility of scratches to produce a separate signal by which a main image signal may be corrected.

Dependencies are inferred from the claim text.