Spatial and temporal sampling has a long history and much has been written in signal processing texts. Color sampling has not been treated with as much rigor, even though the CIE formalized a set of color matching functions in 1931, long before the era of digital signal processing. One reason for the neglect of a formal approach to color sampling is that the goal of color measurements was not to recreate the color spectrum but to describe colors in a consistent quantitative way. Recently, as digital processing of color images has become common, there has been more work that requires that the signals associated with color images be sampled appropriately. Let us consider the problem of sampling color signals and look at the difference between the goal of sampling color and that of sampling spatially or temporally. We will see that the same basic theory can be applied to both problems, but the color sampling requires a more general approach.

Sampling of the radiant power signal associated with a color image can be viewed in at least two ways. If the goal of the sampling is to reproduce the spectral distribution, then the same criteria for sampling the usual electronic signals can be applied directly. An accurate representation of the spectrum is required for modeling the performance of color capture and reproduction devices. However, the goal of color sampling is often not to reproduce the spectral distribution but to allow reproduction of the color sensation.