So i have always found it a problem the magento image generator. And i am always a fan of lossless images, so is google.
So here is a small extension to scan the folders you want it too and optimize the images as lossless. And you can schedule it to do it every so often.
This is pritty much the GTSpeed extension but stripped out all the other features i didn’t need/want.
So if anyone wants to use it download it here: imageoptimizer I am going to add some features to it someday soon when i get some time to make it a bit better.
Just upload the files in the same folder structure it is in into your magento folder.
once uploaded, clear your cache. And a new menu will appear under System > Image Optimise
And a new tab in your System > Configuration to change the settings such as which folder to scan.