glow effect

width = 200
height = 200
passes = 10
sample_diameter = 6

import operator
from datetime import datetime
from PIL import Image, ImageDraw
from math import sin, cos, hypot

image = Image.new('RGB', (width, height), (0, 0, 0, 255))
draw = ImageDraw.Draw(image, 'RGBA')

for x in range(width * 300):
    y = int(round(sin(float(x)/20.0)*height/4.0+height/2.0))
    draw.point((x, y), fill=(255, int(round(255*cos(float(y)/50))), int(round(255*sin(float(x)/100))), 255))

draw.line((0, height / 4, width, height / 2+1))
draw.line((0, height / 4*3, width, height / 2+2))
draw.line((0, height / 5*4, width, height / 2+3))

def blur():
    tmp_image = Image.new('RGBA', (width, height), (0, 0, 0, 0))
    tmp_draw = ImageDraw.Draw(tmp_image, 'RGBA')
    for x in range(width):
        for y in range(height):
            pixel = image.getpixel((x, y))

            if pixel != (0, 0, 0):
                continue

            number_of_samples = 0
            sample_sum = (0, 0, 0)
            sample_radius = float(sample_diameter)/2.0
            xmin = max(0, int(round(x - sample_radius)))
            xmax = min(width, int(round(x + sample_radius)))
            ymin = max(0, int(round(y - sample_radius)))
            ymax = min(height, int(round(y + sample_radius)))
            smallest_value = (255, 255, 255)
            for sample_x in range(xmin, xmax):
                for sample_y in range(ymin, ymax):
                    if hypot(sample_x-x, sample_y-y) > sample_radius:
                        continue
                    number_of_samples += 1
                    sample_pixel = image.getpixel((sample_x, sample_y))
                    if sum(sample_pixel) > 0 and sum(smallest_value) > sum(sample_pixel):
                        smallest_value = sample_pixel
                    sample_sum = tuple(map(operator.add, sample_sum, sample_pixel))

            if sample_sum != (0, 0, 0):
                c = (int(round(sample_sum[0] / float(number_of_samples) + float(smallest_value[0])/5)),
                     int(round(sample_sum[1] / float(number_of_samples) + float(smallest_value[1])/5)),
                     int(round(sample_sum[2] / float(number_of_samples) + float(smallest_value[2])/5)))

                tmp_draw.point( (x, y), fill=(c[0], c[1], c[2], 255) )

    image.paste(tmp_image, (0,0), tmp_image)

print 'Started at ' + datetime.now().strftime("%Y-%m-%d %H:%M:%S")

for i in range(passes):
    blur()

image.show()
image.save(datetime.now().strftime("glow_%Y-%m-%d_%H.%M.%S") + '.bmp')

print 'Finished at ' + datetime.now().strftime("%Y-%m-%d %H:%M:%S")