Artist Alex Law found the photo of the girls in their costume on Tumblr, and included it in her fantastic blog Little Girls Are Better At Designing Superheroes Than You.
From the blog:
One of the main reasons I like these girls’ costumes is because of how simple they are. Often times when artists want to re-design female superheroes to be less sex-objecty they end up changing a bunch of unnecessary stuff. It doesn’t have to be like that, just get rid of Power Girl’s tit window and give Huntress a full leotard. It’s easy!