Screens that use organic light-emitting diodes, better known as OLED and AMOLED, have a unique method of image production. When instructed to display a "black" color, the individual pixel cells are physically turned off, providing the stunning blacks seen on OLED-equipped devices like the Galaxy S II, DROID RAZR and the original Nexus One. Interestingly, this also means that displaying a mostly black image on an OLED screen also draws less power than a white or full-color image. To take advantage of this technological quirk, an intrepid modder on XDA has set about modifying all of Google's core Android apps to save the maximum amount of battery on OLED phones, via the simple expediency of reversing the color scheme.
As you almost certainly know, the vast majority of Google's proprietary apps for Android employ a black-on-white color scheme, the better to aid visibility. If your phone uses an OLED or AMOLED screen, XDA modder "rujelus22" presents his alternative: color-reversed "dark" apps that allow for a high degree of contrast (with admittedly slightly lower readability) and maximum battery-saving black space on the screen. The modified collection of Gingerbread apps includes the standard Gmail, Google Search, Android Market, Google Talk, Music player and Google Plus apps, with Google Voice, Documents, Translate, Twitter, Facebook, DropBox and the Ice Cream Sandwich keyboard thrown in for good measure.
The bad news is that you'll need to get rid of the apps already on your phone in order to install them - for most of the core Android apps, that will require root access. And the apps are designed for Gingerbread, so while they should work on Honeycomb and Ice Cream Sandwich, they won't be ideal replacements for the tablet or phone apps those users already have .There's no conclusive numbers on how much battery power you can save with the modified files, but I'm sure some flashers are eager to take a few measurements. The modder says he or she intends to add more themed apps to the collection over time.
By the way, don't install these if your phone's screen uses an LCD, unless you just like the look. They won't save any battery power at all. If you're unsure of what technology your phone uses, check our Device.ac database.