There are great problems for those who want real responsive images.
Note to self: The lazy, cross-browser, cross-device (desktop and mobile), low overhead, kinda light, solution so far is:
- make your images 2x their display size
- compress them with high compression ratio (30% quality)
- and set their size by css (using media queries if needed)
For an entry point on the subject, you may start here: noupe article