Apple is reportedly testing larger displays for the upcoming iPhone smartphone with boosted screen resolution of 1704 by 960 pixels.

Apple, the renowned smartphone and tablet manufacturer, is looking to surprise customers with its upcoming iPhone model. The latest development in rumors building around the unannounced iPhone is that a boosted screen resolution will be included in one of the two iPhone models. Several media sites have widely reported the so-called iPhone 6 to arrive in two screen sizes, 4.5-inch and 5.5-inch, marking a significant change from the company's traditional 4-inch offering.

Apple is reportedly testing larger displays with a screen resolution of 960 x 1704 pixels, which is a 50 percent increase from Apple's iPhone 5S' screen resolution of 640 x 1136 pixels, 9to5 Mac reports, citing sources familiar with the testing of the upcoming iPhone. However, it remains unclear which of the two iPhone models will feature a boosted screen resolution.

The increased screen resolution on iPhone displays means improved pixel density. Assuming the higher screen resolution debuts in the next phones, the iPhone 6 models will have more pixel density than their predecessors. According to the report, the 4.7-inch model will feature 416ppi while the 5.5-inch model will sport a 356ppi. The current Apple flagship comes with a pixel density of 326ppi.

In addition to the higher screen resolution, the sources add that core user-interface elements, such as Home Screen, Notification Center and Settings Panels, will appear as a visually-extended version of the iOS UI found on the current models. Also, Apple will optimize the apps to fit the larger screen on the new iPhone.

In a separate report earlier this month, an Italian website, Macitynet.it, published photos of an iPhone 6 alongside Samsung Galaxy S5. The mock up showed the comparison between the flagship phones from two biggest smartphone makers.

Apple iPhone 6 has been one of the hottest upcoming gadgets this year. With release date set to sometime in August and September for the 4.7-inch and 5.5-inch model, respectively, more details appear online but with no official news. Apple is also planning to launch the next iOS version at the WWDC in June. Some developments in the iOS8 include a Healthbook app for fitness tracking, improved maps with public transit directions, iTunes Radio app, new split-screen multitasking view for the iPad and more.