When Apple unveiled the iPhone 3GS in mid-2009, it included serious improvements to the built-in camera hardware, bumping the resolution from 2 to 3.2 megapixels. That trend may well continue with the next version of the iPhone: the latest intelligence about CMOS image sensor supplier OmniVision suggests that the company will be supplying Apple with 5 megapixel sensors for the next-generation iPhone, expected to launch in summer.

The original iPhone and the iPhone 3G made use of compact and relatively low-cost imaging hardware consisting of a rather average-performing 2 megapixel CMOS sensor mated to a fixed-focus, fixed-aperture lens. This combination proved serviceable for most average picture taking—even downright good given ample lighting—but definitely suffered in low light, close focus, and tricky lighting scenarios.

For the iPhone 3GS, Apple switched suppliers to OmniVision, utilizing the company's 1/4" 3.2 megapixel CIS paired with a true autofocus lens. This combination offered increased resolution, a truly useful 30 fps video option, and vastly sharper close-up shots. Combined with a "touch to focus" software feature that linked focusing and metering to an area of the image that the user could choose by simply touching the screen, the new hardware proved far superior to previous iPhones.

Taiwan-based DigiTimes, which broke the news of the iPhone 3GS's impending camera upgrade last year, reports that OmniVision is expected to double the number of image sensors—from about 20 million to about 40 million—that it will supply to Apple in 2010. Unnamed sources indicated that an unknown fraction of that 40 million will be the new, 5 megapixel sensors, which Apple will use in next summer's expected iPhone hardware revision.

As many readers may know, packing more megapixels onto the same sized sensor generally results in smaller, less-sensitive pixels. However, OmniVision's 1/4" 5 megapixel sensor uses a technique called backside illumination to maintain—and in some cases increase—sensitivity of these smaller pixels. It works by flipping the traditional architecture of CMOS image sensors upside down, letting light fall on the "back side" of the sensor. This means that more light hits the actual sensing diode in each pixel location.

The result of using backside illumination is that Apple can use OmniVision's 1/4" 5 megapixel sensors as a drop-in replacement for the current 3.2 megapixel one in the iPhone 3GS. It significantly increases the resolution without compromising on low-light performance or requiring a larger lens to accommodate for a larger sensor. These sensors also offer full 1080p HD video resolution at 30 fps—a significant improvement over the iPhone 3GS's paltry VGA video resolution.

DigiTimes was completely accurate when it came to revealing that OmniVision's 3.2 megapixel sensor would be used in the iPhone 3GS, but not so accurate when it reported that cameras with such sensors would end up in revisions to the iPod touch, iPod nano (which ultimately ended up with a low-resolution video camera), and, of all things, the iPod classic. If this latest report is accurate, though, the next iPhone could pack some serious imaging horsepower. It should also keep the iPhone competitive with recently released smartphones such as the Motorola Droid, which have higher resolution camera sensors.