Shading correction on a crt telecine

Abstract

A process and system for forming a video image with a telecine transfer device is disclosed, the process comprising converting a photographic film image into video signals representative of the image with a telecine transfer device which uses a cathode ray tube flying spot scanner in combination with at least one dichroic beam splitting mirror to separate the light from the cathode ray tube into component spectral segments which are then detected by a light detector, wherein a filter is positioned between the dichroic mirror and the light detector to compensate for an inconsistent spectral distribution of light in at least one component spectral segment resulting from a varying angle of incidence of light originating from various positions of the cathode ray tube onto the dichroic mirrors, said filter reducing the magnitude of the range of spectral change due to the varying angle of incidence. In preferred embodiments of the invention, the light from the cathode ray tube is separated into red, green and blue component segments. In a particularly preferred embodiment, a properly designed filter is used such that the spectral distribution of light that reaches the green component light detector results in a substantially consistent side-to-side contrast detection with various photographic film stocks. The instant invention differs from previous methods of shading correction in that the correction is being done optically instead of electronically. The optical correction is substantially film independent.