Optimage is an advanced image optimization app for OS X 10.7+ that you can use for free with some limitations. Optimage uses advanced metrics to automatically adjust image quality for 30-50% smaller image files that are visually perceived as originals.
This app helps you provide smaller images, increase your website speed and save on bandwidth and storage.
Max compression ratio is achieved by exhaustively trying various compression parameters and image data structures using novel and traditional heuristics.
There are 2 versions, a free and a premium version. The free version is limited to processing a maximum of 24 images per day.Download Optimage