This is a Heroku buildpack for using optipng in your application.
It is designed to be used with heroku-buildpack-multi to combine it with the appropriate real buildpack for your app.
This is based on http://github.com/jayzes/heroku-buildpack-ffmpeg, which was in turn based on https://github.com/shunjikonishi/heroku-buildpack-ffmpeg
Add this buildpack to you existing app buildpacks:
$ heroku buildpacks:add --index 1 https://github.com/jayzes/heroku-buildpack-optipng
Create a new release with a Git push. heroku buildpacks:add gives you the exact command line to do this, check its output.
You can verify that everything is properly installed by running the following command:
$ heroku run "optipng -v"