If you want absolutely smallest PNG files i recommend using some thing like [pngcrush](https://en.wikipedia.org/wiki/Pngcrush) or tinypng that you linked.
Our aim was to write a "pretty good" PNG writer with balanced compression and speed. * For super compression using some thing like pngcrush or tinypng but it will take a while. * For fastest image writing speed use some thing like .bmp instead but it will be large. * For most cases use our normal png writer. If these images change rarely doing a pre-processing with pngcrush during deploy is great idea. But if you are serving dynamic images it's better to generate the image fast and send it.
