locs = Position[
   ImageData[Binarize[Rasterize["Mathematica", ImageSize -> 150]]], 0];
Print[StringRiffle[
   StringJoin /@
    ReplacePart[
     ReplacePart[
      ConstantArray[
       " ", {Max[locs[[All, 1]]] + 1, Max[locs[[All, 2]]] + 1}],
      locs -> "\\"], Map[# + 1 &, locs, {2}] -> "#"], "\n"]];