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