Google Nexus One's luminous OLED screen may be state of the art when it comes to display technology in smartphones but an iPhone's LCD screen ranks better, according to tests by DisplayMate, a firm that calibrates and optimizes displays.

"The high-resolution, high-pixel-density OLED display on the Nexus One is beautiful, even stunning on first view, but there are lots of issues, problems and artifacts lurking just below the surface," said Raymond Soneira, president of DisplayMate, on the company's blog.

Since OLED displays are still so new, they are yet to be perfected for use in consumer products, which can result in a less-than-optimal experience, he says.

Organic LED displays, or OLEDs, are gaining favor among gadget makers because they can offer a brighter display at lower power than traditional LCDs. The Nexus One has a 3.7-inch screen and a resolution of 800 x 480 pixels. The iPhone 3G has a 3.5 inch display with a resolution of 480 x 320 pixels.

To test the Nexus One's screen, DisplayMate used 24-bit native resolution 800 x 480 test patterns and 24-bit HD resolution test photos.

Their conclusions? The "peak white brightness" of the Nexus One is low for a display that used often in outdoor settings. In terms of picture quality, the Nexus One photos had "way too much contrast and color saturation, to the point of appearing gaudy," says DisplayMate.

The Nexus One's Gallery app also uses 16-bit color instead of 24-bit color, which results in poor images, says the firm.

Another reason for the Nexus One display's performance could be the "PenTile pixel arrangement" that it uses, says Soneira. Instead of the three sub-pixels of red, green and blue for every pixel, the Nexus One's display just divides each pixel into two. Every PenTile pixel includes a green sub-pixel, but the red and blue sub-pixels appear in alternating pixels, he says.

"In principle, that is only a minor issue because if red or blue isn’t available in a particular pixel, then the display driver can just use one from an adjacent pixel. But in practice, it makes things a lot harder for the software and makes it very likely that artifacts will creep into the on-screen images," says Soneira.

DisplayMate suggests, among other things, Google improve the factory display calibration to correct color saturation and contrast.

Check out their complete two-part series discussing the tests conducted and the results for this Nexus One vs. iPhone 3G shootout.

Not surprisingly, the OLED Association isn't happy with the results. The tests are flawed and just because the OLED screen does not react the same way as an LCD screen does not mean the former is inferior, Barry Young, managing director of the OLED Association told OLED-Display.net.

Photo: Comparing the Nexus One display to the iPhone/ DisplayMate