Using [`FindClusters`](http://reference.wolfram.com/language/ref/FindClusters.html) to group the pixels

    coord = FindClusters[ImageValuePositions[imagem, Red], 5];
    coord = Table[Mean[coord[[i]]], {i, 1, 5}]
    ListPlot[coord]

> {{36., 204.}, {347., 184.}, {150., 149.}, {246., 76.}, {71., 39.}}

[![enter image description here][1]][1]

    Show[
     imagem,
     Graphics@Line@Subsets[#, {2}] &@coord]

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/pU1kr.png
  [2]: https://i.sstatic.net/DXskw.png