Fig. 3

The monochrome pixel color rendering ratio \(\Delta {P}_{k(i-j)}\) values donut chart for each basic color monochrome region in digital photo of shadow puppet artifact's flesh side (Serial Number: 6Y1A7598). \(\Delta {P}_{k(i-j)}\): It is named the monochrome pixel color rendering ratio, and it represents the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between \(\it j\) and \(\it i\). \(\Delta {P}_{k(50-0)}\): The monochrome pixel color rendering ratio which represent the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between 0 and 50. \(\Delta {P}_{k(80-50)}\): The monochrome pixel color rendering ratio which represent the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between 50 and 80. \(\Delta {P}_{k(100-80)}\): The monochrome pixel color rendering ratio which represent the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between 80 and 100. \(\Delta {P}_{k(120-100)}\): The monochrome pixel color rendering ratio which represent the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between 100 and 120. \(\Delta {P}_{k(150-120)}\): The monochrome pixel color rendering ratio which represent the proportion of the area within the monochromatic region \(\it k\) relative to the RGB color space at the monochromatic standard point \({O}_{k}\), subject to a color tolerance condition between 120 and 150