Comment by JyrkiAlakuijala

I wasn't able to convince myself about that when approaching that question with with back-off-the-envelope calculation, published research and prototypes.

Very few applications are constantly decoding images. Today a single image is often decided in a few milliseconds, but watched 1000x longer. If you 10x or even 100x energy consumption of image decoding, it is still not going to compete with display, radio and video decoding as a battery drain.