File:Pixel sample size.gif

# by drummyfish, released under CC0 1.0

from PIL import Image
import math

SIZE = 64
SCALE = 4

IMG_SIZE = SIZE * SCALE

SAMPLES = 10

SAMPLES_TOTAL = SAMPLES * SAMPLES

STEP = 0.1
STEPS = 15

FRAMES = STEPS * 2 - 1

RECT_SIZE = 30
RECT_OFFSET = 20
RECT_POS = IMG_SIZE - RECT_SIZE - RECT_OFFSET
RECT_COLOR = (255,0,0)
SAMPLE_COLOR = (0,255,0)

def isInSet(x,y):
  dx = x - 28
  dy = y - 28
  dist = math.sqrt(dx * dx + dy * dy)

  dist2 = abs(y - (x * 3 - 40))

  return (dist > 23.5 or dist < 20.5) and dist2 > 2

image = Image.new("RGB",(IMG_SIZE,IMG_SIZE),"white")

pixels = image.load()

width = 0.0

for frame in range(FRAMES):
  print("frame " + str(frame))

  step = width / SAMPLES

  for y in range(SIZE):
    for x in range(SIZE):
      hits = 0

      for sy in range(SAMPLES):
        for sx in range(SAMPLES):
          if isInSet(x + sx * step, y + sy * step):
            hits += 1

      color = int(255 * hits / float(SAMPLES_TOTAL))

      c = (color,color,color)

      for i in range(SCALE):
        for j in range(SCALE):
          pixels[(x * SCALE + i, y * SCALE + j)] = c

  sampleWidth = int(width * RECT_SIZE)
  sampleStart = RECT_POS + (RECT_SIZE - sampleWidth) / 2

  for y in range(sampleWidth):
    for x in range(sampleWidth):
      pixels[(sampleStart + x,sampleStart + y)] = SAMPLE_COLOR

  for i in range(RECT_SIZE):
    pixels[(RECT_POS + i,RECT_POS)] = RECT_COLOR
    pixels[(RECT_POS + i,RECT_POS + RECT_SIZE - 1)] = RECT_COLOR
    pixels[(RECT_POS,RECT_POS + i)] = RECT_COLOR
    pixels[(RECT_POS + RECT_SIZE - 1,RECT_POS + i)] = RECT_COLOR

  image.save("sampling" + str(frame + 1).rjust(2,"0") + ".png")

  if frame < STEPS:
    width += STEP
  else:
    width -= STEP