The rumor, from Vietnamese blog Tinhte.vn (via MacRumors), claims the new information originated from an inside source at iPhone camera module maker Wonderful Saigon Electrics.
A higher quality imager has been a much-rumored feature for the forthcoming iPhone, dubbed "iPhone 5S" by many, as the current iPhone 5 carried over the 8-megapixel unit from the iPhone 4S. That package boasted a large f/2.4 aperture and a backside illuminated sensor, and offered performance improvements over previous models when taking pictures in dark environments.
The camera module in the iPhone 5 went largely unchanged besides the addition of sapphire glass to the lens assembly, which served to protect against scratches.
With the upcoming iPhone 5S said to be launching later this year, a new camera module could likely be one of the handset's major spec bumps as a redesign is not expected. Apple may also institute a revamped optics/sensor system to minimize "purple fringing" seen in some instances with the current module, a byproduct of compact camera systems with short focal lengths.
Tinhte has been accurate in previous reports, and was the first to leak a video of Apple's EarPods design.