Question: Two surfaces that have the same color under one light and different colors under another are often referred to as metamers. An optimal color is a spectral reflectance or radiance that has value 0 at some wavelengths and 1 at others. Though optimal colors don't occur in practice, they are a useful device (due to Ostwald) for explaining various effects.
• use optimal colors to explain how metamerism occurs.
• given a particular spectral albedo, show that there are an infinite number of metameric spectral albe does.
• use optimal colors to construct an example of surfaces that look very different under one light (say, red and green) and the same under another.
• use optimal colors to construct an example of surfaces that swop apparent color when the light is changed (i.e. surface one looks red and surface two looks green under light one, and surface one looks green and surface two looks red under light two).