Put Your Site on a Diet With Google's Image-Shrinking 'WebP' Format
An image may be worth a thousand words, but it sure takes a lot longer to download. Google's WebP image format may offer some help though, shrinking images more than popular formats like JPEG. Not every browser supports Google's nascent WebP image format, but it's pretty simple to serve up smaller images to those that do.
WebP versus JPEG. Click the image to see the full size examples on Google's WebP comparison page.Image: Google