For black and white and gray images with sub-pixel rendering, there is up to a factor of 3 improvement in image sharpness. (displaymate.com)
We'll discuss below how Apple can improve image sharpness on the mini iPad. (displaymate.com)
The display has Diamond Pixels (see below) and Sub-Pixel Rendering with 518 pixels per inch (ppi), providing significantly higher image sharpness than can be resolved with normal 20/20 Vision at the typical viewing distances of 10 inches or more for Smartphones, so the display appears perfectly sharp. (displaymate.com)