“…More recently, the introduction of skin color measurements has extended this to include the potential for objective determination of skin features, 1 including melanin and hemoglobin concentrations, 2-6 the depth and diameter of blood vessels, 7-9 the depth of pigmented skin lesions, 10,11 the maturity and depth of bruises, 12,13 and keratin fiber arrangements. 14 Such advances have proved invaluable for the advancement of skin laser treatments 15 and photodynamic therapy, [16][17][18] and have contributed to further advances in the diagnosis of cancerous and noncancerous skin lesions. 10,[19][20][21] However, the success of these methods depends entirely upon adequate knowledge of the behavior of light as it impinges upon, and travels through, the skin.…”