[mistercow]

So specifically on a backlit LCD screen with dimming zones, and in the specific case where an entire zone would have originally been blue or red (which are perceptually dimmer), you could plausibly get a small amount of energy savings. But “twice the battery life” from this is not plausible.

[ssl-3]

Specifically backlit LCDs. Maybe with dynamic backlight; maybe even with zoned dynamic backlight -- but definitely backlit LCDs. It only works in corner cases where important information would normally be displayed as bright saturated subpixels (colors), and even then it only really gets good with special dynamic processing (which probably doesn't exist).

So in terms of practicality: It has none.

And at best, all that these hypotheticals can do is stretch out a battery a little longer by reducing the intensity of backlight that is necessary in order to succeed at using the device in a given level of ambient light.

It has never been my intent to demonstrate "twice the battery life" ["with this one simple trick!"]. That's the path of nonsense, and of chemtrails. :)