Python PIL Fill an image with a color outline

I have a picture that is in PNG format with no background. What I am trying to do is fill this image with yellow only till the edges. Picture 1 is what I have and Picture 2 is what I want. picture 1

enter image description here

I am not really sure how to achieve this goal or how to start it. because both the background and the inside of the pic is transparent.

I wish there was a function where I can tell python find edges and fill inside till edges

from PIL import Image, ImageFilter

image ='picture1.png')
image = image.filter(ImageFilter.FIND_EDGES).fill(yellow)'new_name.png') 


In my case, the ImageDraw floodfill works like a charm. What is not working for you?

import os.path
import sys

from PIL import Image, ImageDraw, PILLOW_VERSION

def get_img_dir() -> str:
    pkg_dir = os.path.dirname(__file__)
    img_dir = os.path.join(pkg_dir, '..', '..', 'img')
    return img_dir

if __name__ == '__main__':
    input_img = os.path.join(get_img_dir(), 'star_transparent.png')
    image =
    width, height = image.size
    center = (int(0.5 * width), int(0.5 * height))
    yellow = (255, 255, 0, 255)
    ImageDraw.floodfill(image, xy=center, value=yellow)
    output_img = os.path.join(get_img_dir(), 'star_yellow.png')

    print('Using Python version {}'.format(sys.version))
    print('Using Pillow version {}'.format(PILLOW_VERSION))

Output image:

Output of the program above

Version information:

Using Python version 3.6.2 (default, Aug  3 2017, 13:46:16) 
[GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.42)]
Using Pillow version 4.3.0