Is there a trademark/copyright concern with altering a Superman logo and using the altered work on a magazine cover.

Be careful. Even though consumers of Superman goods might not be confused, DC Comics would not necessarily refrain from taking action. They are currently suing a barbershop in Orlando for using the Superman name. I have included a copy of the complaint below.

There is a substantial concern and you are risking a law suit. The issue here would be whether your use of a modified superman logo constitutes fair use and/or is otherwise protected under the First Amendment. It is always difficult to provide an opinion on the issue of fair use, which requires consideration of multiple variables as they apply to the specific facts and circumstances of your case. However, let's be practical here--the owners of trademark and copyrights in superman logos and characters are known to be very aggressive in enforcing their rights. Thus, absent a license, you run a significant risk of an expensive law suit if you proceed in this manner. Of course, we all know of many instances in which clear violations of trademarks and copyrights owned by others are tolerated because the owners of these IP rights make a calculated decision that the cost of enforcement is not worth the benefits. But no lawyer on a general web-site such as this can bless your proposed use of the modified Superman logo and character on a T-shirt.

A nicely practical answer from Ms. Korsyn. Allow me to add that so many alterations of the Superman logo have been made and used ... with largely ineffectual complaint from the mark proprietor ... that the level of risk is fairly small. In other words, it is highly dilute and almost trite outside of the field of actual motion pictures and clearly related goods (action figures and such.) The same overuse and triteness supports an argument of parody in the copyright context.

The essence of trademark infringement is consumer confusion, and that means using a trademark (or one that's confusingly similar) in commerce in a way that misleads about the trademark's use or affiliation. Here, the proposed use isn't on a product in commerce, such as on t-shirts being sold, it's on a t-shirt worn to riff on the Superman-like qualities of the subject. No consumers of Superman goods would be confused, so I don't think it's a concern. But context is everything, so have your magazine's lawyers review the proposed layout.