Samsung Galaxy Note 3's Diamond Sub-pixels Mask PenTile's Weakness

BY WESLEY FENLON ON OCT. 1, 2013 AT NOON

DisplayMate finds no flaw with the Galaxy Note 3's new OLED display, which is incredibly bright and pixel dense.

DisplayMate's latest investigation into mobile display technology reveals that Samsung's Galaxy Note 3 has one hell of a screen. Not only is the resolution doubled, from 720p to 1080p, but it's "the best performing OLED display to date across the board, including picture quality and color accuracy." More importantly, the Note 3's brightness maxes out at an incredibly bright 660 cd/m2, much higher than the Galaxy S 4's 475 cd/m2 and the iPhone 5's 556 cd/m2.

PHOTO CREDIT: FLICKR USER RETROCACTUS VIA CREATIVE COMMONS

OLEDs are making huge gains on LCDs, and one of the key factors is the arrangements of subpixels Samsung uses in its displays. In the past, Samsung's PenTile pixel arrangements have been criticized for damaging image quality, and one look at a macro comparison between an LCD screen and an OLED screen will show you why. The issues with PenTile sub-pixel arrangements haven't disappeared, but you may not be able to notice them with the naked eye, as DisplayMate explains:

"The Galaxy Note 3 has a pixel density of 388 Pixels Per Inch PPI, which is very high, but lower than the 441 PPI for the Galaxy S4 and other Full HD Smartphone displays. It’s important to recognize that this is not a decrease in visual image sharpness because the display still appears perfectly sharp for 20/20 Vision at typical viewing distances of 13 inches or more because the Pixels and Sub-Pixels are below normal visual acuity. (The Galaxy Note is 14 percent larger than the Galaxy S4 so it is typically held further away). The Galaxy Note 3 also has a PenTile Sub-Pixel arrangement like the Galaxy S4, with only 2 Sub-Pixels per Pixel instead of the usual 3. But at these very high PPIs, it’s not visually noticeable because of the use of Sub-Pixel Rendering and the Diamond Sub-Pixel arrangement..."

That diamond sub-pixel arrangement is something new that Samsung introduced with the Galaxy S 4 and has worked into the Note 3 as well. In typical LCD displays, each pixels is made up of three red, green, and blue sub pixels. In PenTile arrangements, every pixel has a green sub-pixel, but red and blue subpixels are alternated. This makes it easier and cheaper to create a higher resolution display. Samsung's new diamond pattern further modifies the traditional sub-pixel arrangement.

IMAGE CREDIT: SAMSUNG

Here's how DisplayMate describes it: "First of all, the Red, Green, and Blue sub-pixels have very different sizes – Blue is by far the largest because it has the lowest efficiency, and Green is by far the smallest because it has the highest efficiency. The alternating Red and Blue sub-pixel PenTile arrangement discussed above leads to a 45 degree diagonal symmetry in the sub-pixel layout. Then, in order to maximize the sub-pixel packing and achieve the highest possible PPI, that leads to diamond rather than square or stripe shaped Red and Blue sub-pixels. But not for the Green sub-pixels, which are oval shaped because they are squeezed between two much larger and different sized Red and Blue sub-pixels."

LCDs may still win for sharpness and color accuracy, but the diamond pattern allows for extremely high PPIs, making it difficult for the naked eye to spot the lack of blue and red pixels.

In fact, DisplayMate writes that OLEDs may soon overtake LCDs in power efficiency, too: "We measured an impressive 26 percent improvement in power efficiency between the Galaxy Note 3 and Note II. While LCDs remain more power efficient for images with mostly white content (like text screens, for example), OLEDs are more efficient for darker content because they are emissive rather than transmissive like LCDs. In fact, Galaxy Note 3 is already 31 percent more power efficient than the Full HD LCD Smartphones we recently tested for mixed image content (that includes photos and videos, for example) with a 50 percent Average Picture Level, APL. If this keeps up then OLEDs may pull ahead of LCDs in total power efficiency in the near future…"

If going beyond 1080p is next for Samsung's smartphone displays, PenTile seems like the obvious way to go. Without microscopes, smartphone users won't be able to spot the difference in image quality at extremely high pixel densities, and OLEDs are poised to be more efficient across the board. The Note 3 received high marks in color accuracy, screen reflectance, and everything else; check out DisplayMate's full analysis for the rest of the details.