Feathered edges on image with Pillow

Question

I'm trying to figure out how to feather the edges of an image using Pillow with Python.

I need something like this cute cat (ignore the visible edges):

I tried im.filter(ImageFilter.BLUR) but is not what I'm looking for.

Answer 1

Have a look at this example:

from PIL import Image
from PIL import ImageFilter

RADIUS = 10

# Open an image
im = Image.open(INPUT_IMAGE_FILENAME)

# Paste image on white background
diam = 2*RADIUS
back = Image.new('RGB', (im.size[0]+diam, im.size[1]+diam), (255,255,255))
back.paste(im, (RADIUS, RADIUS))

# Create blur mask
mask = Image.new('L', (im.size[0]+diam, im.size[1]+diam), 255)
blck = Image.new('L', (im.size[0]-diam, im.size[1]-diam), 0)
mask.paste(blck, (diam, diam)) 

# Blur image and paste blurred edge according to mask
blur = back.filter(ImageFilter.GaussianBlur(RADIUS/2))
back.paste(blur, mask=mask)
back.save(OUTPUT_IMAGE_FILENAME)

Original image (author - Irene Mei):

Pasted on white background:

Blur region (paste mask):

Result: