levelHF.gif was generated from
level.gif using these commands:

> giftoppm level.gif|ppmtopgm|levcon -free 200 -maxiter 300 -limres 0.5
  |ppmtogif -sort > levelHF.gif


metalHF.gif was generated from
metal.gif using these commands:

> giftoppm metal.gif|ppmtopgm|levcon -maxiter 30|ppmtogif -sort > metalHF.gif


metal.jpg was rendered with POV-Ray using metalHF.gif.
level.jpg was rendered with POV-Ray using levelHF.gif.
