This is a Heroku Buildpack to use libjpeg 62 (6b).
With heroku-buildpack-multi,
$ heroku config:add BUILDPACK_URL=https://github.com/heroku/heroku-buildpack-multi.git
$ cat .buildpacks
https://github.com/heroku/heroku-buildpack-ruby.git
https://github.com/a2ikm/heroku-buildpack-libjpeg62.git