message: Use stderr for error messages
diff: @@ -75,7 +75,7 @@ bool hdr_image::load(std::string const& filename)
  if (res.size() != 4)
  {
  - std::cout << "Error: invalid resolution string in HDR file\n";
  + std::cerr << "Error: invalid resolution string in HDR file\n";
  }
  if (res[0] == "-Y" && res[2] == "+X")
  @@ -85,7 +85,7 @@ bool hdr_image::load(std::string const& filename)
  }
  else
  {
  - std::cout << "Error: unsupported resolution string in HDR file\n";
  + std::cerr << "Error: unsupported resolution string in HDR file\n";
  }
  // scanlines ------------------------------------------
  