IIRC, ImageOptim is a front end for a bunch of CLI image compression tools. So, in theory, you could roll your own for a CI system if you figured out all the arguments that ImageOptim was passing to those tools.
> Automates ImageOptim, ImageAlpha, and JPEGmini for Mac to make batch optimisation of images part of your automated build process.
> Mac
Why would anyone run a CI server on a Mac?