import Image import math im = Image.new("L", (32,32)) radius = 16 for i in range(32): for j in range(32): x = abs(i - 16) y = abs(j - 16) d = math.sqrt(x * x + y * y) if d < radius: t = 1.0 - (d / radius) im.putpixel((i, j), int(255 * (t * t))) im.save("blob.png")