human skin tone pigmentation diversity infographic diagram

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