Responsive images are hard to get right

Jump on over to the creater of this blog's theme and read about the wizardy that makes sure you get the right size and quality pictures for every brand of smart phone/computer. You would not want to download a 6MB image with dimensions of 2400x2450 for example on a phone. The code that this blog is built on will only send a small file to an iPhone wile sending a large image to a desktop.
Amazing stuff.