Q:

Java Open Source Image Optimization libraries

I'm trying to gather information about all java open source libraries which are focused on image optimization. 
One of these is pngtastic, but it deals only with png images. Do you know any other similar libraries?

A:

Seems like there aren't many open source java libraries dedicated to image optimization. But there are quite many libraries offering image optimization as part of their features.
For example:
im4java is a pure java library offers interfaces to ImageMagick, which can be used to optimize images.
ImageJ, it can be used as a library according to this answer

