But a simple histogram stretch can be done with very little processing power by modern standards. 50 ms on one core of the application processor would be enough.

I think they just chose bad examples. The results from this Google Research blog post are much much more impressive:

https://research.googleblog.com/2017/04/experimental-nightti...

I wish my smartphone could do _that_ automatically.

You end up with a lot more noise with simple histogram adjustment from a single image, plus the dynamic compression to a final 8bit image won't look as good for many use cases.

Exposure fusion from multiple images has much higher usable dynamic range and lower noise.

Thanks for that. That was amazing.

Faster and supposedly uses much less power.

> Using Pixel Visual Core, HDR+ can run 5x faster and at less than one-tenth the energy than running on the application processor (AP).

Not just faster but more energy efficient I presume. That's especially important when taking long videos.