The paper addresses a problem of perceptual artifacts that appear in saturated colors of Y'CbCr non-constant luminance 4:2:0 HDR video. A computationally inexpensive method is proposed for converting 4:4:4 HDR video to Y'CbCr 4:2:0 non-constant luminance format. The method shows similar objective performance to an iterative algorithm and outperforms a previously published explicit solution. The method removes artifacts in areas with saturated colors, obtaining results in one step. Compared to the iterative algorithm, the proposed solution significantly decreases the worst-case and average complexity.