Image Analysis Tools to Quantify Visual Properties of Hair Fiber Assemblies 320 curl indices of 2.25±0.15, 1.58±0.16, and 1.19±0.24 for African, artificially curled, and frizzy hair, respectively. These data represent an average of measurements for five fibers of each hair type. Hair Color Factors responsible for hair color: The natural hue of hair is a direct result of its melanin content it can be due to eumelanin or pheomelanin, or a combination of these pigments. Additional pigments also found in hair consist of the kynurenines and several pigments that are believed to only be found in red hair types, such as Figure 11. Images of hair with various degrees of curvature in the relaxed and fully extended states