BOM and accessibility
The BOM publishes weather radar data online. This is awesome. The palette they use is practically useless for colour-blind people. This is NOT awesome.
The luminance of the scale they use is all over the place. Here is a sample image., and here is the same image in black and white. See how easy it is to make out without relying on hue? Although I can see colours, the scale at the bottom of the image gives a good idea of how easily I can differentiate the scale in the radar map. i.e. badly.
I threw together a few lines of Python that will change the palette of the images to something that is useful for colourblind people:
# This requires the Python Imaging Library. If you're running Ubuntu or Debian
# apt-get install python-imaging
import Image
existing_palette = [ (245,245,255), (180,180,255), (120,120,255), (20,20,255),
(0,216,195), (0,150,144), (0,102,102), (255,255,0),
(255,200,0), (255,150,0), (255,100,0), (255,0,0),
(200,0,0), (120,0,0), (40,0,0) ]
new_palette = [ (255-v*32,255-v*32,255) for v in xrange(7) ] + [ (v,v,255-v*32) for v in xrange(8) ]
palette_map = dict(zip(existing_palette, new_palette))
def map_pal(pal):
"""change the palette. PIL uses concatinated RGB triplets as a palette format
"""
inp = list(pal)
out = []
while len(inp) > 0:
p = tuple(inp[:3])
out.extend(palette_map.get(p,p))
inp = inp[3:]
return out
if __name__ == "__main__":
import sys
img = Image.open(sys.argv[1])
pal = img.getpalette()
pal = map_pal(pal)
img.putpalette(pal)
img.save(sys.argv[2])
Here is the image above converted. (I'm not dealing with the GIF transparency properly).
Incidentally, the storm going over Sydney at the moment is INSANE.
The luminance of the scale they use is all over the place. Here is a sample image., and here is the same image in black and white. See how easy it is to make out without relying on hue? Although I can see colours, the scale at the bottom of the image gives a good idea of how easily I can differentiate the scale in the radar map. i.e. badly.
I threw together a few lines of Python that will change the palette of the images to something that is useful for colourblind people:
# This requires the Python Imaging Library. If you're running Ubuntu or Debian
# apt-get install python-imaging
import Image
existing_palette = [ (245,245,255), (180,180,255), (120,120,255), (20,20,255),
(0,216,195), (0,150,144), (0,102,102), (255,255,0),
(255,200,0), (255,150,0), (255,100,0), (255,0,0),
(200,0,0), (120,0,0), (40,0,0) ]
new_palette = [ (255-v*32,255-v*32,255) for v in xrange(7) ] + [ (v,v,255-v*32) for v in xrange(8) ]
palette_map = dict(zip(existing_palette, new_palette))
def map_pal(pal):
"""change the palette. PIL uses concatinated RGB triplets as a palette format
"""
inp = list(pal)
out = []
while len(inp) > 0:
p = tuple(inp[:3])
out.extend(palette_map.get(p,p))
inp = inp[3:]
return out
if __name__ == "__main__":
import sys
img = Image.open(sys.argv[1])
pal = img.getpalette()
pal = map_pal(pal)
img.putpalette(pal)
img.save(sys.argv[2])
Here is the image above converted. (I'm not dealing with the GIF transparency properly).
Incidentally, the storm going over Sydney at the moment is INSANE.