Install optipng

You can download optipng from

http://optipng.sourceforge.net

To install optipng, run

cd /usr/local/src
wget -O optipng-0.7.7.tar.gz http://prdownloads.sourceforge.net/optipng/optipng-0.7.7.tar.gz?download
tar xvf optipng-0.7.7.tar.gz
cd optipng-0.7.7/
./configure
make
make install

Binary will be installed at

/usr/local/bin/optipng