What is the ruling on looking at pictures of naked women or naked people in medical textbooks for the purpose of study and learning?

The basic principle is the impermissibility of looking at images of nudity. However, it is permissible out of necessity, such as for studying medicine, provided that it is limited to the extent of the necessity, that one restrains oneself from deriving pleasure from looking, and that the books are protected from being seen by unqualified individuals. Jurists have permitted a doctor to see the 'awrah of a patient out of necessity.