[lifthrasiir]

And if you use the same technique to WebP Lossless, which is generally better than PNG for most cases, you will find that it hardly improves the compression. This is to be expected because underlying algorithms are same for both, but WebP uses a slightly more tweaked algorithm to exploit more patterns in 2D images. A code and in general text is not a 2D image, so there is nothing left to exploit.