Because we define white in the chromaticity diagram as x= X/(X+ Y+ Z) = 0.333, y = Y/(X + Y + Z) = 0.333, we need a transform that maps X= Y= Z= 1 to R= G= B= 1. To achieve this, we modified the XYZitu601-1 (D65) standard conversion matrix to have rows that add up to 1. The International Telecommunications Union standard matrix is