This buildpack was made years ago and is not maintained anymore, it includes binaries which are most probably not on the last version available. Instead of using it directly, I would suggest you to fork it and update the binaries to the last version.

Add binaries for image-optim on Heroku, can be used with heroku-buildpack-multi.

Built-in support for image-optim gem, creation of .image-optim.yml config file.

Binaries in this buildpacks :

• advpng
• gifsicle
• jpegoptim
• jpegtran
• optipng
• pngcrush

Binaries are in this git repo in vendor/image-optim

On compilation :

• Binaries are copied into vendor/image-optim
• Symlink to binaries is added to ensure next buildpacks will have binaries available
• vendor/image-optim is added to PATH through a .profile.d script
• Add config file .image-optim.yml if Gemfile present
• Version of each binaries is displayed