Blurring does not work correctly when the face takes most of the image

[zorun]

I tried the current code on profile pictures, where the face takes most of the image. It does not work correctly:

• on some pictures, only the eyes are blurred, especially for people with glasses
• on some pictures, only part of the face is blurred (i.e. either the hair, the beard, the ears, half of the face...)
• on some pictures, nothing is blurred at all

It almost feels like the algorithm does not find a rectangle wide enough in the JPEG structure, so it settles on smaller rectangles that don't cover the face completely.

My test pictures are small and square (between 200x200 and 300x300 pixels). Obviously I can't share examples.