function getLeftmostPoint(y)
  local x1 = 0
  while x1 < img.width and img.getInt(x1, y) >= 0xF00000 do
    x1 = x1+1
  end
  return x1
end

function getRightmostPoint(y)
  local x2 = img.width
  while x2 > 0 and img.getInt(x2-1, y) >= 0xF00000 do
    x2 = x2-1
  end
  return x2
end

function getWidth(y)
  local x2 = getRightmostPoint(y)
  local x1 = getLeftmostPoint(y)
  return math.max(0, x2-x1)
end

function getAverageWidth(y1, y2)
  local sum = 0
  for y = y1, y2-1 do
    sum = sum+getWidth(y)
  end
  return sum/(y2-y1)
end

function upperWidthToLowerWidth()
  local upper = getAverageWidth(0, math.floor(img.height/3))
  local lower = getAverageWidth(math.floor(img.height*2/3), img.height)
  return upper/lower
end