import PIL.Image as Image
import PIL.ImageDraw as ImageDraw
import PIL.ImageFilter as ImageFilter
import PIL.ImageStat as ImageStat
import PIL.ImageChops as ImageChops

image = Image.open('output2.png').convert('RGB')
mask = Image.open('mask.png').convert('RGB')

mask = mask.point([0] * 256 + [0] * 255 + [255] + [0] * 256)
mask = mask.convert('1')

mask2 = mask.filter(ImageFilter.MaxFilter(5))
mask = ImageChops.difference(mask2, mask)

stat = ImageStat.Stat(image, mask)
threshold = stat.sum[0] / stat.count[0]

image = image.point([255 * (i > threshold) for i in range(256)] * 3)

image.save('output3.png')