The core feature of OLED displays is their ability to turn off “unneeded” light sources behind subpixels – this allows them to offer a completely dark black, and furthermore save power when displaying “partial colors”.
So far, nobody has studied this phenomenon in detail – enter Jeff Sharkey. This Android engineer did just that:
Take, for example, the Nexus One. If powering only the red pixels at full intensity draws a current “i”, then powering all green pixels draws “1.5i”, and all blue pixels “2i”. (These ratios are derived from empirical measurements, and don’t hold in all cases.) Also, it’s worth noting that OLED displays don’t have backlights like LCD, meaning that darker colors draw less power.
If you could power only the red pixels you could save quite a bit of power.
So I started poking around SurfaceFlinger, the low-level window compositer on Android. I brushed off my OpenGL skills and after a few hours I had simple proof-of-concept. A couple hours later I had several filters between red-only and full-color:
Even though I am not sure whether anyone of you is willing to give up color display in exchange for longer battery life, hit the URL below to see his amazing numbers and a bunch of photographs: