When the DC boxset was released on LD in 1993, there was one magazine article that mentioned the transfers were done at the corrrect "gamma levels", so the garbage mattes wouldn't show up as previous video transfers were done too bright. I don't think they were ever visible in the movie theatre. Video and film are different beasts after all.
I know from experience a movie theater can project a print too dark either through being careless, or a bulb that needs replacement, but could they also project too "hot" or bright as well? Steven Spielberg once made a comment about tweaking various print runs on Raiders(?) to cope with theater chains notorious for "bad projection".