A new method for evaluating display life of digital printing materials is discussed. We propose a new criterion for estimating end points using “Modified Image Grade N'” which integrates monocolor fading, gray fading, stain and their balance. It shows the retention of total image quality. We can estimate end points using some threshold of “N'”. Xenon light exposure testing was performed on some digital printing materials such as AgX, D2T2, xerography, and inkjet color photographic prints. End points were calculated on each material with “N'” and other criteria such as ISO 10977. An end point with “N'” matches subjective evaluation better than other methods that define end points separately for color image, gray image, and stain.