According to the Nexus One specs, it has a 800×480 AMOLED display.
According to Wikipedia, this is what makes an AMOLED display different from standard LCD:
- It does not need a backlight, the pixels emit light themselves. This allows for thinner display.
- Only the turned-on pixels consume power. In average AMOLED uses less power than LCD. The power usage is dependent on the color displayed — a black screen uses much less power than a white screen.
- The contrast is very good. The black is very deep (as there’s no backlight leakage).
- The viewable angle is very large; this is often a problem with LCD, particularly TN (twisted-nematic), which have small viewing angles.
- OLED has better reponse rate than LCD.
- The lifetime of OLED is shorter than LCD. Only the period a pixel is lightened (turned-on) counts towards the lifetime. The blue subpixels have the shortest lifetime.
Glossing over the technical details, the result is that the Nexus One has a *great* display. It is the highest quality display I’ve ever seen (but I can’t say how it compares to the Droid display as I have not seen a Droid phone yet). The Nexus display is large and high-density, is very crisp, the colors are very saturated, and the black is indeed very deep. WVGA, 800×480 is quite a high resolution for a display of this size (a more typical resolution for this size would be HVGA, 480×320 as on the G1).
After getting used to the Nexus display, when you look back to your previous phone’s display you’ll be shocked by how low-quality the old LCD seems now.
The AMOLED display on Nexus has one more surprise on hold: On Nexus, each pixel is composed of only two subpixels instead of the usual three (Red, Green, Blue) subpixels of an LCD. The following picture should help understand the subpixel pattern on a Nexus: (source)
So every pixel contains a green subpixel, and alternating a red or a blue subpixel. A pixel has either red or blue subpixels but not both.
Why is it done this way? This technique allows for a larger physical area for the blue and red subpixels, thus increasing their lifetime. It also allows to implement the high pixel count (800×480) by using only two thirds of the subpixels that would normally be needed (2subpixels/pixel instead of 3subpixels/pixel).
What is the impact of this unusual subpixel pattern? Natural images (such as pictures, movies etc) are very well reproduced and likely the subpixel impact is not perceivable. Synthetic images that contain pixel-aligned thin and saturated lines (red or blue) allow to discern the “alternating” subpixel pattern. But as the display is very high density and the pixels are very small, most likely you would never become aware of the subpixel pattern if not looking explicitly for it.
What is the impact of AMOLED for application developers:
- First of all, you may not care at all about AMOLED vs LCD, and everything will work just fine.
- You can use darker colors to save power. You may prefer white-text-on-black-background to black-on-white-background, as the dominant black color uses less power on AMOLED. (the dominant color makes no power difference on classical LCD).
- You may prefer using darker colors to increase the display lifetime. You may prefer avoiding displaying intense blue (as it has the lowest lifetime) for long periods of time.
- If you want to draw highest-resolution thin lines, they are best rendered in green — because the green subpixels have double the resolution of red and blue subpixels.
It seems the choice of subpixel pattern is also related to human eye physiology, as the human eye is more sensible to green than to blue, and keeping green at full resolution gives rich image information to the eye.