[Galaxy Note 10.1 (2014 Edition) General] BarryH_GEG:
Seriously? :rolleyes:

The effective PPI of the N10.1-14's display is 299 PPI. It's achieved somewhat by slight of hand by using combinations of sub-pixels to create the illusion of more. That's the very definition of PenTile whose impact varies greatly based on implementation. My simple formula is essentially just factoring in the loss of 25% of the RGB sub-pixels to the added white ones and distributing the lost pixels across each of red, green, and blue. .

From WiKi...

PenTile RGBW technology, used in LCD, adds an extra subpixel to the traditional red, green and blue subpixels that is a clear area without color filtering material and with the only purpose of letting backlight come through, hence W for white. This makes it possible to produce a brighter image compared to an RGB-matrix while using the same amount of power, or produce an equally bright image while using less power.

The PenTile RGBW layout uses each red, green, blue and white subpixel to present high-resolution luminance information to the human eyes' red-sensing and green-sensing cone cells, while using the combined effect of all the color subpixels to present lower-resolution chroma (color) information to all three cone cell types. Combined, this optimizes the match of display technology to the biological mechanisms of human vision.[13] The layout uses one third fewer subpixels for the same resolution as the RGB stripe (RGB-RGB) layout, in spite of having four color primaries instead of the conventional three, using subpixel rendering combined with metamer rendering. Metamer rendering optimizes the energy distribution between the white subpixel and the combined red, green, and blue subpixels: W <> RGB, to improve image sharpness.

The display driver chip has an RGB to RGBW color vector space converter and gamut mapping algorithm, followed by metamer and subpixel rendering algorithms. In order to maintain saturated color quality, to avoid simultaneous contrast error between saturated colors and peak white brightness, while simultaneously reducing backlight power requirements, the display backlight brightness is under control of the PenTile driver engine. When the image is mostly desaturated colors, those near white or grey, the backlight brightness is significantly reduced, often to less than 50% peak, while the LCD levels are increased to compensate. When the image has very bright saturated colors, the backlight brightness is maintained at higher levels. The PenTile RGBW also has an optional high brightness mode that doubles the brightness of the desaturated color image areas, such as black&white text, for improved outdoor view-ability.​

RGBW is funky in that when displaying certain fully saturated colors (yellow and green have been given as examples) on a white background there's some granularity issues on hard graphics edges.

Also from WiKi...

However, for the same resolution and size the PenTile screen can appear grainy, pixelated, speckled, with blurred text on some saturated colors and backgrounds when compared to RGB stripe color. This effect is understood to be caused by the restriction of the number of subpixels that may participate in the image reconstruction when the color is fully saturated. In the RGBW case, this is caused as the W subpixel will not be available in order to maintain the saturated color. For all other cases, text and especially full color images are fully reconstructed.​

The impact of PenTile depends on PPI and even more so on visual acuity - the point at which the viewer's vision intersects one arcminute. For people with 20/20 vision holding a device the typical 10-12" away you can't see that the N10.1-14's display is PenTile; at least from a clarity perspective. Some people here with 20/10 vision have seen the RGBW saturation issue. I, with 20/20 vision, haven't.

Here's an interesting article talking about PPI and its impact on various content...

http://arstechnica.com/gadgets/2012/10/1080p-on-a-smartphone-screencan-it-possibly-matter/

Here's an interesting article talking about visual acuity in the context of Apple naming their display "retina"...

http://www.anandtech.com/show/3794/the-iphone-4-review/4

The pixel race explored...

http://www.anandtech.com/show/7743/the-pixel-density-race-and-its-technical-merits