Price, Gess & Ubell
Negative/positive microfilm discriminating system
 A negative-positive microfilm discriminating system for use in a microfilm reader/printer apparatus, comprising a sensor for detecting the densities at a plurality of spots within an image zone of a microfilm strip, and a control circuit for discarding a fraction of the density data when the fraction of the data is representative of a density occurring at less than a predetermined percentage of the total number of spots and discriminating whether the microfilm strip is a negative or a positive on the basis of the remaining fraction of the density data. 
Minolta Camera Kabushiki Kaisha
G
G03B
inventional
Yasushi Takao Masafumi
Yamade Saijo Fujita