cross section of normal and freckles skin layer on white background.

freckles skin pigmentation hyperpigmentation face melanin melanocyte body small flat spots sun exposed ephelides solar lentigines actinic discoloration complexion areas tan red light brown dark melanogenesis pigment spot layer cell epidermis dermis sunburn exposure melasma vector infographic design diagram inflammation unhealthy dermatology beauty treatment care damage lesion change ultraviolet childhood concept summer 202408comparison normal comparison isolated white background cross healthy melanocytes develop