Abstract: A photographic film can be regarded as an information transmission channel. In this case, input is the optical image and output is the photographic image. Although the image information is continuative and should be treated as a continuous information channel, it can be simplified to a discrete channel and treated by a shrinkaging quasi-noiseless channel model due to the existance of graininess in photographic materials. In this paper, the channel capacity of color photographic materials was studied using the concept of muti-layer Shannon's entropy and parallel information channels, and a calculating formula was derived. The Color Infrared Aero Negative Film Typa 1821 was selected as the sample. A set of measurement and calculation programmes on the PDS microdensitometer-computer system were developed.

Key words: color photographic film, information capacity, image evaluation