Composite filter for reducing target illumination angle dependence
A. C. Hanson, Robert D. Buzzard, James C. Kirsch, Jeffrey A. Loudin, Don A. Gregory · Optical Society of America Annual Meeting · 1992
It has been found that binary phase only filters made of real-world scenes are sensitive to changes in the target illumination angle. The illumination angle dependence for several cases will be measured, and a novel technique for reducing this illumination angle sensitivity will be introduced. A filter composed of sections of several filters is used to reduce scene illumination dependence. These filters are made with the target illuminated from different angles, and the resultant filter is more tolerant to changes in target illumination. The filter construction technique as well as results obtained when such a filter is used will be discussed.