>From the article, the source data is in pixel format. No codec format can be better than the source data. Not necessarily true. For example if I have a bitmap

>From the article, the source data is in pixel format. No codec format can be better than the source data. Not necessarily true. For example if I have a bitmap picture of a printed circle, I can use software to find the shape and convert it to a vector representation of a circle (which would be infinitely better than the source image). It works very well with scanned line art, for example.