import Image
from cStringIO import StringIO
import psyco
psyco.full()

histogram = {}

png_header = '\x89PNG'
frames = open("allflights.mpng").read().split(png_header)
for frame in frames:
    if not frame:
        continue

    # Put the PNG header back on and decompress the PNG
    im = Image.open(StringIO(png_header + frame)).convert("RGBA")

    # Plot each red pixel on the histogram
    for i, pix in enumerate(im.getdata()):
        if pix == (255, 0, 0, 255):
            histogram[i] = histogram.get(i, 0) + 1

hist = open("flights.hist", "w")
width = im.size[0]
for i, count in histogram.items():
    y = i / width
    x = i % width
    hist.write("%d %d %d\n" % (x, y, count))