[ft] ftgrays.c problem

[CHU Run-min]

in function gray_render_cubic()

    level = 1;
    da    = da / ras.cubic_level;
    db    = db / ras.conic_level;
    while ( da > 0 || db > 0 )
    {
      da >>= 2;
      db >>= 3;
      level++;
    }

I think da should be divided by conic_level and db by cubic_level
according to the context, or my mistake.