skin tone pigmentation mechanism in dark skin

skin pigmentation melanin epidermis complexion dark black melanocyte brown keratinocyte melanosome anatomy tone pigment hair dermis olive ethnicity phototype hyperpigmentation vitiligo cell health medicine body diversity human illustration eumelanin pheomelanin treatment dermatology cosmetology skincare melasma africanamerican asian hispanic structure tissue basal diagram crosssection vector infographic process ultraviolet tan coloration