Responsive Image Container

After writing about the possibility of using progressive JPEGs as a solution to responsive images I'm really encouraged to see an image format solution being given attention and the Responsive Image Container has the ability to solve some of the problems a progressive JPEG solution cannot, such as the issue of art direction.

So in summary, the idea behind a Responsive Image Container is a new image format that would use an initial file range or manifest to inform the browser about the layers the file contains and the resolutions for which they are applicable. The browser can then fetch the layers it needs, each layer containing only the additional pixels that are not already present in the previous layer so thereby allowing the browser to just download the extra detail it needs.