from PIL import Image, ImageDraw
import math

im = Image.new("L", (720, 360))
draw = ImageDraw.Draw(im)

im_org = Image.open("File:Geolocated_images_in_Wikimedia_Commons_2012-01-21.png")
l_im = im_org.convert("L")

for x in range(720):
    for y in range(360):
        c = l_im.getpixel((x, y))
        if not c: continue
        c = 10**(10**(c/380.0)-1.2)-10
        if c <= 0: # so far this never occurred
            print "%f -> 1.0" % c
            c = 1.0
        c = round(math.log(c, 2)*16)
        draw.point((x,y), fill=c)

im.save("File:Geolocated_images_in_Wikimedia_Commons_2012-01-21_remake.png", "PNG")