Generate Hirst–like circles

circles.py

import datetime
import hashlib

from PIL import Image, ImageDraw


def circles(across, down, radius):
    # Scale the image up by 4, to anti-alias.
    scale = 4
    render_radius = scale * radius
    width = (2 * across - 1) * (2 * render_radius)
    height = (2 * down - 1) * (2 * render_radius)

    im = Image.new('RGB', (width, height), '#ffffff')
    draw = ImageDraw.Draw(im)

    for x in xrange(0, across):
        center_x = 4 * x * render_radius
        for y in xrange(0, down):
            center_y = 4 * y * render_radius
            colour = hashlib.md5(datetime.datetime.utcnow().isoformat()).hexdigest()[:6]
            draw.ellipse((center_x, center_y, center_x + 2 * render_radius, center_y + 2 * render_radius), fill='#' + colour)

    im.thumbnail((width / scale, height / scale), Image.ANTIALIAS)
    im.save('circles.png')


if __name__ == '__main__':
    circles(4, 4, 48)