pamscale - scale a Netpbm image

   pamscale
      [
         scale_factor
         |
         {-xyfit | -xyfill | -xysize} cols rows
         |
         -reduce reduction_factor
         |
         [-xsize=cols | -width=cols | -xscale=factor]
         [-ysize=rows | -height=rows | -yscale=factor]
         |
         -pixels n
      ]
      [
         [-verbose]
         [
            -nomix
            |
            -filter=functionName [-window=functionName]
         ]
         [-linear]
      }
      [pnmfile]