Install optipng from source
optipng is image optimize for PNG format.
You can download it form
http://optipng.sourceforge.net/
To install, run
cd /usr/local/src wget https://excellmedia.dl.sourceforge.net/project/optipng/OptiPNG/optipng-0.7.7/optipng-0.7.7.tar.gz tar xvf optipng-0.7.7.tar.gz cd optipng-0.7.7 ./configure make make install