I have heard of draft laws that would have made it a crime for parents to take pictures of their children in the bathtub. For adults to induce minors to engage in sex acts for their entertainment should be criminal, whether they take pictures of it or not.
Intellectual property is controversial among libertarians.
For those who believe in it, there can be no property right in images made by coercion, including exploitation of minors. Libertarians who don't believe in intellectual property might tolerate distribution of child pornography that chanced to fall into the hands of innocent parties. For myself, call me undecided. In any case, the issue is protection of the minors, not controlling what kinds of things people can see. Computer images, no problem.