Optimizing png images with optipng for Google Page Speed

To optimize png images on ubuntu 14.04 we will use optipng.

Installation :

sudo apt-get install optipng

How to use :

optipng /home/user/Image/footer-logo.png -o4

Compression ratio :

Defined by the -oX attribute, where x is a number.

-o0 <=> -o1 -nx -nz
-o1 <=> [use the libpng heuristics] (1 trial)
-o2 <=> -zc9 -zm8 -zs0-3 -f0,5 (8 trials)
-o3 <=> -zc9 -zm8-9 -zs0-3 -f0,5 (16 trials)
-o4 <=> -zc9 -zm8 -zs0-3 -f0-5 (24 trials)
-o5 <=> -zc9 -zm8-9 -zs0-3 -f0-5 (48 trials)
-o6 <=> -zc1-9 -zm8 -zs0-3 -f0-5 (120 trials)
-o7 <=> -zc1-9 -zm8-9 -zs0-3 -f0-5 (240 trials)

You may need to run it with sudo in some cases.

Search in all subfolders :

It is possible to search and optimize all subfolders of a directory. We will search for all png photos and process them with the optimizer.

find /var/www/project.loc/uploads -name *.png -exec optipng -o4 '{}' \;

find - makes it possible to search for files with the desired format in a given directory.

-exec - makes it possible to perform certain manipulations with the found file.