Apple is boosting the screen display prowess of the upcoming iPhone 5S, doubling the screen resolution of the handset and in the process prepare the way for the unleashing next year of iPhone 6 with Retina+.

According to Unwired View, citing reports from Chinese blog site WeiPhone, Apple could come up with an iPhone 5S that boasts of a 1600 x 900 screen resolution, made possible by a pixel count jump of up to 1.5 million from the iPhone 5's 730,000.

The refreshed iPhone, however, will maintain its 4-inch screen size while adopting a front design that is reminiscent of the iPad Mini - having narrow bezels around the handset screen.

Yet the most exciting part of the new report is the high possibility that enhanced Retina panel is making its way to an iPhone model with larger screen size. It is not remote, according to Gotta Be Mobile, that Apple would soon dispatch a 4.8-inch smartphone that sports a slightly higher pixel density from the iPhone 5's 325ppi.

"An iPhone 6 with a 4.8-inch display would still deliver a 382ppi rating," the report said.

This particular make would eliminate the supposed technology trade offs that Apple CEO Tim Cook said is a major concern to be addressed prior to the release of an iOS-powered smartphone beyond the 4-inch mark.

In deploying first the Retina+ with the 5S, Apple would buy more time in reconfiguring the overall iPhone 6 experience, ensuring at the same time that its launch next year would be problem-free.

The WeiPhone report also indicated that the iPhone 5S would hit the market September this year and by delivering Retina+ with the gadget, the tech giant would largely confirm iPhone 6's arrival in the quarters to follow.

Analyst have estimated that the rumoured Apple phablet is geared for a June 2014 release date and it will represent a major make-over of the iPhone design template, with likely reengineered profile and control buttons.

The oversized smartphone is also expected to bring in more exciting features thanks to the revamped iOS 7 that Apple will reportedly unveil next month.