Image outline using python/PIL

Question

I have a color photo of apple, how can I show only its outline (inside white, background black) with python/PIL?

Answer 1

If your object and background have fairly well contrast

from PIL import Image
image = Image.open(your_image_file)
mask=image.convert("L")
th=150 # the value has to be adjusted for an image of interest 
mask = mask.point(lambda i: i < th and 255)
mask.save(file_where_to_save_result)

if higher contrast is in one (of 3 colors), you may split the image into bands instead of converting it into grey scale.

if an image or background is fairly complicated, more sophisticated processing will be required