gistfile1.txt

In [1]: pixels = []

In [2]: colours = (0, 85, 170, 255)

In [3]: for r in colours:
   ...:     for g in colours:
   ...:         for b in colours:
   ...:             pixels.append((r, g, b))
   ...:             

In [4]: len(pixels)
Out[4]: 64

In [5]: import png    

In [6]: p = png.from_array(pixels, 'RGB;8')

In [7]: p.save('foo.png')