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 :
Binaries are in this git repo in
On compilation :
Copy the snippet above into CLI.