******************************
Joe D here!  Here's some stuff about PTRframetable.
  Name               Size           Offset
    ============================================
      width              word           $00  height             word
      $02
        Unknown            word           $04  Unknown            word
        $06
          Unknown            long           $08  Unknown            long
          $0C
            PTRframedata       long           $10  Unknown
            long           $14
              Some of those unknown word pairs may really be longs, and
              some of those
                unknown longs may be word pairs.
                  PTRframedata points to stuff that looks to be pixel
                  data.
                    For each pixel line ("height" the PTRframetable),
                    there is a word giving the
                      amount of data, followed by that many bytes of
                      data.
                        You'll notice that some of the data doesn't fill
                        the pixel line completely,
                          and in some cases is one or two bytes wider
                          than the image.  I think you're
                            supposed to center it.  The start position
                            could be calculated by:
                              (width - bytecount) / 2.  But I may be
                              wrong.****************************
