Gurman has the exact specifications of one of the new iPhone models Apple is testing. He says the iPhone 6 will have a 1704 x 960 resolution display.
That means the 4.7-inch phone will have a 416 pixels per inch. The current iPhone has a 4-inch screen and 326 pixels per inch. More pixels per inch means a sharper screen. The 5.5-inch iPhone 6 would have 356 pixels per inch, which is less than the 4.7-inch phone, but still more than the current iPhone.
Gurman also notes that each time Apple makes major design changes to the iPhone, it also tweaks the resolution to fit the new dimensions. For example, when Apple increased the iPhones screen size from 3.5 inches to 4 inches with the iPhone 5 in 2012, the screen resolution changed from 960 x 640 to 1136 x 640.
Gurman arrived at his conclusion by noting that from a developer's perspective, the iPhone 5, 5s, and 5c have a "base resolution" of 568 x 320. However, these phones actually have twice as many pixels to display images at a 1136 x 640 resolution although developers are creating apps at a 568 x 320 scale.
Sources familiar with the situation told Gurman that Apple plans to triple this "base resolution" with the iPhone 6, which would result in a 1704 x 960 resolution display. This would mean that Apple's new iPhone(s) would also maintain the same 16:9 aspect ratio found on the iPhone 5, 5s and 5c.
It's important to note, however, that this is based on one specific iPhone 6 test model, so it may not reflect the final product.
The report comes at a time when both Samsung and LG are upping the display quality of their flagship smartphones. LG, for example, will outfit its next G3 smartphone with a quad-HD 2,560 x 1,440 resolution display, which would make it one of the first phones to feature a screen that sharp. Most high-end Android phones have 1080p full HD screens, while the iPhone has been stuck at 1136 x 640 for the past several generations.
That being said, critics have continuously praised the iPhone's screen despite the fact that its specs don't match up to its rivals, which further proves speculation that the difference in smartphone display quality when bumped up to 1080p isn't very noticeable to the human eye.
Apple is expected to introduce at least one new iPhone model at in September. Some reports have suggested that the larger 5.5-inch smartphone could be delayed until 2015.