Developer Jeff Sharkey has come up with an Android hack for OLED display phones (Nexus One, Incredible, etc) that he claims almost doubles battery life: go into “night vision” mode by filtering “separate pixel elements for each color channel” so that only one color shows at a time (red works best) .
First of all, it’s worth noting that he did this hack in airplane mode with GPS off, though it doesn’t seem that that is necessary for the hack to work. As Sharkey puts it:
Filtering to show only red pixels only requires 35% of the original baseline OLED panel current, on average. Adding back the baseline current, the best case overall is about 42% of the original system current, effectively doubling the battery life. Also, showing only red pixels doubles as an awesome night vision mode, perfect for astronomy.
The hack uses a “low-level window compositer” called SurfaceFlinger. Video after the break.