When nudity is pornographic.

“And who is so barbarous as not to understand that the foot of a man is nobler than his shoe, and his skin nobler than that of the sheep with which he is clothed.” - Michaelangelo
This will be a hard topic to cover but I'm going to simplify it for you because it's absolutely important to understand so you don't fall into the traps of false ideologies on sexual imagery.
It's hard because we struggle to define what the truth is about sexuality and nudity. Our secular masters make us believe it's subjective. It's all taste. No absolute truth.
Wrong.
Puritans believe sexuality is inherently evil. The naked body is bad. They're also wrong.
What if I told you there is another way?
At this point, you know porn is bad if you follow me for a while now.
Many young men and women struggle to define what pornography is. When is something pornographic? Is nudity inherently bad? On what basis do we define when something is porn or art?
We could be looking at the same piece of art displaying nudity while only one of us is driven to lust.
How does this happen?
It happens because of a selfish mindset which is caused by an obsession with the body, separated from the person who owns it.
In distinguishing the erotic and the pornographic we are really distinguishing two kinds of interests: interest in the embodied person and interest in the body- and, in the sense that I intend, these interests are incompatible. - Roger Scruton, Beauty.
Pornography turns a subject into an object. The object, a female body, is owned by a person. That person is a soul. Porn removes the person from the body, thus corrupting the source of her beauty.
A beautiful nude painting isn't explicit. Botticelli's Birth of Venus is a great example. Venus is portrayed naked but she doesn't illicit lust. What Botticelli masterfully achieved is covering her body with her own body.

She wears an invisible outfit. You don't see that in porn. Porn leaves nothing open to the imagination. Its only purpose is to derange you by addressing demonic sexual fantasies.
Porn is solely made to arouse sexual desire. Erotic art portrays the beauty of human sexuality.
If you feel aroused by erotic art then the artist made an aesthetic defect.
Aesthetic defects happen when the artist paints his subjects in sexually explicit ways or paints too many details of the genitals and breasts. Or too much reality in general.
Erotic art should be transcendent, surreal, and otherworldly.
When art mimics the reality of sex too much it becomes like a picture. Pictures are snapshots of reality. Pictures require little effort and patience. There is no room for the artist's own interpretation.
That's why porn is almost always recorded and if it's drawn, you see it's always sexually explicit and detailed. Even more explicit because drawn pictures like hentai can exaggerate the female and male body parts.
Nudity in Playboy magazines is different from Boucher's Blond Odalisque.

Yes, both contain nudity but you'll notice straight away, you don't feel driven to lust by Boucher's painting. The woman in the painting is distant because she could be anyone.
She doesn't have an address, a name, or a social media account. You can't fantasize about her because she doesn't appear like a real human being.
With Playboy models, it's the complete opposite. You can find endless content about them, driving you into the rabbit hole of sexual decadence.
Boucher's painting might provoke sexual thoughts in your mind but keeps you contained in a safe place because you know the woman isn't real.
That's a different story from a real woman, photographed and available for your pleasure.
Pornography is a war on beauty and the integrity of our bodies. The case against porn is an inherently good cause because it protects the creation of God. Our bodies are made in the image of Him.
Porn desecrates this fact by reducing us, human beings with souls, to nothing more than a piece of flesh to be used for one's selfish sexual desire.
Botticelli's Venus is not erotic: she is a vision of heavenly beauty, a visitation from other and higher spheres and a call to transcendence. - Roger Scruton, Beauty.