Light Absorption in Heterogeneous Systems with Application to Photographic Dye Images*

A quantitative theory for the absorption of light by colloidal suspensions of spherical particles has been developed and extended to polydispersed systems. It has been applied to photographic dye images. The density, covering power, and efficiency of light absorption in a particulate image are defined in terms of the particle-size distribution, the molar absorbance of the dye, and the composition of the image. Well-substantiated by the experimental evidence, the theory quantitatively explains the loss in absorption efficiency and the broadening of spectral absorption bands in a particulate dye image.