Nov 24th, 2014
From the project page:
Set JPG quality per image style
This module allows you to specify a custom quality on different image styles you create. After installing and enabling this module, you will have the option to add a new effect to your image styles, enabling you to change the quality.
Uses and Application
Having high quality images improves the visual quality of your site. Problems can arise where you have dynamic content such as a page background images that users can upload. Having high image quality can lead to 2mb+ download sizes when using full 1920x1024 image styles. With this module, you can scale the quality of your large images down and leave your smaller thumbnails at your defined default.