Python code to extract rain intensity colors from FMI rain radar maps.

rainRadarExtract.py

from PIL import Image 
import colorsys

def rgb2hsv(rgb):
  r = rgb[0] / 255
  g = rgb[1] / 255
  b = rgb[2] / 255

  hsvRaw = colorsys.rgb_to_hsv(r, g, b)

  hsv = []
  hsv.append(int(hsvRaw[0] * 360))
  hsv.append(int(hsvRaw[1] * 100))
  hsv.append(int(hsvRaw[2] * 100))

  return hsv


def colorFunc(pixel):

  waterbody = (0,0,0)

  if (210,224,228) == pixel: # sea
    return waterbody

  if (210,224,230) == pixel: # lake
    return waterbody

  # HSV
  hsv = rgb2hsv(pixel)

  # Text antialiasing (gray)
  if hsv[1] < 5:
    return (0,0,0)

  # Combined road, border, shore (warm-colored grayish)
  if 17 < hsv[0] < 202 and hsv[1] < 30:
    return (0,0,0)

  # Rain colors
  # blue
  if 208 <= hsv[0] <= 217 and 16 <= hsv[1] <= 38:
    return pixel

  # blue 2
  if 20 <= hsv[0] <= 206 and 44 <= hsv[1] <= 56:
    return pixel

  # turq 1 & 2
  if 163 <= hsv[0] <= 181 and 38 <= hsv[1] <= 63:
    return pixel

  # green
  if 82 <= hsv[0] <= 92 and 60 <= hsv[1] <= 69:
    return pixel

  # yellow
  if 58 <= hsv[0] <= 64 and 63 <= hsv[1] <= 71:
    return pixel

  # orange 1
  if 46 <= hsv[0] <= 51 and 64 <= hsv[1] <= 69:
    return pixel

  # orange 2
  if 27 <= hsv[0] <= 32 and 63 <= hsv[1] <= 73:
    return pixel

  # red
  if 5 <= hsv[0] <= 9 and 68 <= hsv[1] <= 72:
    return pixel

  return (0,0,0)


files = []
files.append("1.png")
files.append("2.png")

for fileNro, filename in enumerate(files):

  newFilename = filename.replace(".", "_rain.")
  img = Image.open(filename)
  new = Image.new('RGB', (img.width, img.height))

  for x in range(img.width):
    for y in range(img.height):
      pixel = img.getpixel((x, y))
      color = colorFunc(pixel)
      new.putpixel((x, y), color)

  new.save(newFilename)