Anybody who follows Apple (NASDAQ:AAPL) is probably familiar with John Gruber and his Apple-focused website, Daring Fireball. Ahead of the iPhone X launch, Gruber called into question a key iPhone X specification from KGI Securities' Ming-Chi Kuo -- one of the best-connected Apple analysts around.

In particular, Kuo said the display resolution of the iPhone X would be 2,800 by 1,242 pixels, with a portion of the display reserved as a so-called function area. Kuo predicted that the remaining 5.15-inch display area, excluding the function area, would measure 2,436 pixels tall and 1,125 wide.

Gruber argued against this view and put forth his belief that the iPhone X's display would measure 5.8 inches along the diagonal and sport a resolution of 2,436 by 1,125 pixels.

He was proved totally correct.

A woman holding an iPhone 8 in Gold at an Apple store in Taipei, Taiwan.

Image source: Apple.

In that same post, he observed that the 2,800-by-1,242 resolution would make perfect sense for a hypothetical 6.6-inch iPhone.

Combine Gruber's analysis with the supply-chain rumors that Apple is prepping a 6.46-inch OLED iPhone next year in addition to a direct successor to the 5.85-inch iPhone X, and I think we now know the display resolution and pixel density of the upcoming 6.46-inch iPhone.

Slightly sharper than this year's iPhone X

An iPhone with a 6.46-inch display with a resolution of 2,800 by 1,242 pixels would have a pixel density of about 474 pixels per inch. That would mean the screen on next year's 6.46-inch iPhone would be about 3.5% sharper than this year's iPhone X -- and, almost certainly, next year's 5.85-inch iPhone X successor.

In other words, there'd be no real noticeable difference in the sharpness of the displays of the two devices. The 6.46-inch iPhone X successor would just be a larger -- not necessarily better -- version of its 5.85-inch counterpart.

This would be in sharp contrast to what we saw with all of the liquid crystal display (LCD)-powered iPhones, beginning with the iPhone 6 and 6 Plus and running through the iPhone 8 and 8 Plus. iPhone 6, 6s, 7, and 8 each had 4.7-inch LCDs measuring 1,334 by 750 pixels, and iPhone 6 Plus, 6s Plus, 7 Plus, and 8 Plus had 5.5-inch LCDs with 1,920 by 1,080-pixel displays.

The pixel densities of the 4.7-inch iPhone displays are 326 pixels per inch; for the 5.5-inch iPhone displays, that figure was 401 pixels per inch -- a 23% increase in sharpness.

Indeed, a sharper display is one of the reasons I, and probably many others, preferred the larger-screen iPhones to their smaller-screen counterparts.

The bad news for Apple -- though I'm loathe to refer to it that way -- is that an improvement in display sharpness won't be a major selling point for next year's 6.46-inch iPhone X, potentially holding back iPhone average selling prices. 

The good news -- for customers, at least -- is that customers should be able to pick between the two devices primarily based on their preferred display size rather than be pushed to buy a larger device that they might not be totally comfortable with just to get a sharper screen.

Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has a disclosure policy.