As a website maintainer one usually needs to reduce the average image file size on a website in order to save bandwidth. A tool I just started using on linux is pngquant to reduce the size of my site’s PNG images prior to upload. This is based on a Nairobi linux users group thread. Pngquant also is available for windows and mac on their website.
convert *.jpg *.png
Install pngquant and via terminal. I use Ubuntu 16.04.
sudo apt install pngquant
I then use pngquant to reduce the all PNG file sizes in the folder as detailed here.
pngquant --speed 1 --verbose *.png
The input image file from a previous post is thus reduced from 47kB to 23kB. Here is a direct visual comparison below: