Comparison between the number of discernible colours in a digital camera and the human eye

Since an input device is not a colorimeter and its opto-electronic behavior is not ideal, its color gamut is smaller than that of the CIE- 1931 XYZ standard observer. A chromatic discrimination model and packing algorithm to the color discrimination ellipses have been used to compute the number of distinguishable colors within the frontiers of MacAdam’s optimal color loci. We have found that, due to the short dynamic range of the digital camera response, this distinguishes considerably fewer dark colors than light ones, but relatively much more colors with middle lightness (Y between 40 and 80, or L* between 69.5 and 91.7).This research was supported by the Ministerio de Ciencia y Tecnología (Spain) under grant DPI2002-00118