Black and white multispectral images have found use as inputs to various image analyzing instruments and for densitometrically determining spectral signatures. Due to redundancy of information, spectral bands sensed have been reduced in number to essentially the three layer sensiti-vities of color infrared film. Since a rather meager bank of true multi-spectral photography exists, it has been deemed cogent to investigate the practicality of deriving black and white multispectral images from multi¬layer color infrared film. Not only is the potential data bank increased, but problems of registration are reduced and camera systems are rendered simp1er.nThe technique of separation involves confining light by means of a separation filter to a very narrow spectral band which matches the maximum density wavelengths of a layer modulation being extracted and in which the dye densities of the unwanted layers are low.nErrors inherent in the technique are of a low order of magnitude and result not only from interlayer interference during the separation process， but from overlap of dye-forming layer sensitivities characteristic of color infrared f Pint "as well. Silver masking techniques can compensate for them but the size "of the error usually does not warrant this extra trouble.nWhen used as inputs to the IDECS image analyzing instrument, the black and white transparencies separated from a color infrared original performed as well or better than multispectral' images originally exposed onto black and white film.
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