I'm the author of the article. You make an excellent point here. It's very hard to quantify image quality. While true, you do need to have the lossless source f

I'm the author of the article. You make an excellent point here. It's very hard to quantify image quality. While true, you do need to have the lossless source files (http://jjcm.org:8081/webp http://jjcm.org:8081/webp) if you want to do a true comparison from the original, but in the real world I'd venture to guess you wont have those; that's why I felt it was unnecessary for most readers.