I am looking for a perfect way to smooth edges of binary images. The problem is the binary image appears to be a staircase like borders which is very unpleasing for my further masking process.

I am attaching a raw binary image that is to be converted into smooth edges and I am also providing the expected outcome. I am also looking for a solution that would work even if we increase the dimensions of the image.

Problem Image Expected Outcome

To preserve the sharpness of a binary image, I would recommend applying something like a median filter. Here is an example of this:

from PIL import Image, ImageFilterimage = Image.open('input_image.png')
image = image.filter(ImageFilter.ModeFilter(size=13))
image.save('output_image.png')

which gives us the following results:

Figure 1. Left: The original input image. Right: The output image with a median filter of size 13.

Increasing the size of the filter would increase the degree of smoothing, but of course this comes as a trade-off because you also lose high-frequency information such as the sharp corner on the bottom-left of this sample image. Unfortunately, high-frequency features are similar in nature to the staircase-like borders.