What would it take to convince you, more pictures?
Of course a photo that hasn't been artistically altered would be convincing. It just seems clear that the delta shield has been a recurring theme for the film's promotion -- these posters remind us of that. The subtle delta shield pattern, as seen in this posters, could be just an "easter egg" of sorts -- a little detail for us to catch, just like the delta reflected in their eyes. The graphic designers might also have decided that the uniforms needed some sort of texture when printed in monochrome on large posters. At this point, the delta pattern could just be an artistic addition.