Usage: nearblack [--help] [--help-general]
          [-of <format>] [-white | [-color <c1>,<c2>,<c3>...<cn>]...]
          [-near <dist>] [-nb <non_black_pixels>]
          [-setalpha] [-setmask] [-alg twopasses|floodfill]
          [-o <outfile>] [-q] [-co <NAME>=<VALUE>]... <infile>