A woman is shown through a window undressing - she is shown naked from behind before she puts on a robe. Her behind and side of her breast are shown.
A number of people run from a room wearing black robes with apparently nothing on underneath. Two of the women take off their robes as they run out, they are shown naked from behind.
A man and a woman kiss and then have sex outdoors, both are naked. She is shown on top first from behind and then in front. Breasts are shown as well as thrusting. No male nudity.
A woman is shown wearing suggestive clothing--she then lifts her skirt to show her underwear and we see bare outer thigh and some of her buttock. She rubs the man's crotch suggestively. Later, we see her undress from behind, showing her entire bare back and butt.
The artwork in the Ninth Gate book is woodcuts, several of which include depictions of topless women, but as woodcuts the level of realism is low.