The transparency of PNGs for the file size of JPEGs
Transparent PNGs are great, but they come at a price: file size. Wouldn't it be nice if there were transparent JPEGs instead? Unfortunately there is no such thing, but ZorroJS gives you the power of transparent PNGs for the size of a JPEG.
It achieves this by combining the image and the transparency mask inside the same image and uses JavaScript and Canvas to create a transparent bitmap the moment it has been loaded. All you need to do to reduce the file size of your transparent images to 50% or less is to include the Zorro.js library and a tiny bit of code.
On http://quasimondo.com/ZorroJS you can convert your current PNGs to the ZorroJS image format.