Gah, can someone explain how the first png in the article (pyramid.png) came to be well over 1 megabyte? Simply opening it and resaving in gimp brings it down t

Gah, can someone explain how the first png in the article (pyramid.png) came to be well over 1 megabyte? Simply opening it and resaving in gimp brings it down to 83kb and running it through optipng will bring it down to 45kb.