Ellipsoidal color difference equations are used to calculate a volume of acceptable color difference, based on the color of the Reference and the specified tolerance. CIEDE2000 and CMC (l:c) are both ellipsoidal color difference equations, and they may both be used for color evaluation of textile and other materials in many applications. The current data (see references 6.1 through 6.7) indicate that the CIEDE2000 metric performs slightly better in terms of agreement with visual evaluations. It is therefore being recommended as the primary color difference method to use for instrumental evaluations.