[chandler5555]

us code 106 gives the copyright holder exclusive rights of derivative works

so yes even at home, making art for a book you dont have permission for, and isnt seen by anyone but you, is still copyright infringement

[fenomas]

Yes, but that doesn't mean it's "illegal" to create a derivative work. It just means that the original author has rights they can exert over what you make.

[chandler5555]

I dont know everything i read online says its copyright infringement to create derivative works, outside of stuff like parodies, fair use and getting permission.

[fenomas]

> outside of stuff like .. fair use

That's the important bit - the things you called illegal a few comments back were obvious examples of (presumptive) fair use.

More generally, whether something is copyright infringement can be vague and subjective - so the bar for going around saying "yes, that is infringement" is not "does it meet a description I read online?". The bar is: "have courts previously ruled that a very similar case was infringement?".