Urban and Grigat [Color research and Application 31: pages 229-238] proposed an iterative method for the inversion of the Cellular Yule-Nielson modified Neugebauer model. The method involves matrix and vector multiplications per iteration. Urban et al [CIC15, pages 178-183, 2007] reported that the computational costs per iteration could be reduced by introducing the singular value decomposition of the matrix. In this paper, “QR” decomposition for the matrix is introduced. The matrix “Q” is an orthogonal matrix and “R” represents an upper triangular matrix. Using this kind of decomposition, an upper triangular matrix is involved per iteration; hence the computational cost can be further reduced comparing with the work of Urban et al (2007).