It’s really tedious to do it manually and something like OpenCV shines.
We found a repo [1] with python code that automatically detects and blurs faces. This script was one of many, except it had a very high accuracy. Over 90%.
Removing exif data is a great idea.
[1] github.com/telesoho/faceblur
Perhaps it’s better to remove the section of photo with a person’s face instead? Or draw a shape over their face and flatten the image? It seems to me as long as the pixels are there the identifying data is there for anyone willing to spend the time and effort to find it.
Edit: Apparently it was interpol, not the US government. I can't find the reddit thread but here's a NYT article with the photo: https://thelede.blogs.nytimes.com/2007/10/08/interpol-untwir...
That can't be done with a blur. In a blur, pixels are merged or averaged together and information is lost. In some cases you could sharpen it a little, but it's still not going to be as good as the original image. In a really good blur, even the best sharpen algorithm isn't going to give you something that looks like an identifiable face.