I'm the author. I just saw this post. I actually cheated to make that illustration better. In a real grayscale image, 0 is black and 255 is white. I inverted t

I'm the author. I just saw this post. I actually cheated to make that illustration better. In a real grayscale image, 0 is black and 255 is white. I inverted the image to make the numbers easier to see as an "8". I swapped it so that black was 0 and white was 255 :)