Every EPiServer developer knows that editors love to work with high-resolution images. If those images are not optimized for different devices, they may increase the page loading time and ruin the browsing experience. There is nothing worse than serving 5000x5000px images on a device whose viewport is only 400x700px, or sending big images (15mb+) over a 3G network. The days of fixed-width website design is behind us. HTML5 has support for responsive images using picture element.