get("#348") -- bright and rgb

maxLen = 20 -- maximum sensible length of signature

-- from Java class "SegmentCounter"

function countSegments(y, flip)

  local lastPix = 1

  local segments = 0

  for x = 0, (flip and h or w)-1 do

    local pix = bright(rgb(flip and img.getInt(y, x) or img.getInt(x, y)))

    if pix >= brightnessThreshold and lastPix < brightnessThreshold then

      segments = segments+1

    end

    lastPix = pix

  end

  if lastPix < brightnessThreshold then segments = segments+1 end

  return segments

end

function getSegmentCount(flip)

  local s = ""

  local lastN = 0

  for y = 0, (flip and w or h)-1 do

    local n = math.min(countSegments(y, flip), 9)

    if n ~= lastN then

      s = s..n

      if #s > maxLen then return end

    end

    lastN = n

  end

  if lastN == 0 and #s > 0 then

    return s:sub(1, #s-1)

  else

    return s

  end

end

w, h = img.width, img.height

brightnessThreshold = 0.9

s = getSegmentCount(true)

if s then

  return "Horizontal signature: "..s

end