Camera phones are undeniably handy for capitalizing on the unexpected photo op. But even the most casual photographers have been loath to give up their standalone digital still cameras and rely on camera phones for capturing "important" images. Image sensor companies and camera phone designers must work their way down a long and formidable to-do list if camera phones are to make competitive headway against standalone DSCs.

Among the technology challenges: enabling handsets to take better pictures in low light and adding high-performance features, such as autofocus and optical zoom, without compromising the phones' ultrathin profiles or ratcheting up the cost in a market already heavily subsidized by mobile- network operators.

Indeed, compared with standalone DSCs, "camera phones have 20 times less space to work with, and they need to cost 20 times less," said Jess Lee, vice president for the mainstream-products business at imaging-chip vendor OmniVision Technologies Inc. Those realities have some vendors questioning whether it's worth anyone's effort to turn a camera phone into a high-end digital still camera.

Studies have found that "90 percent of camera phone users never print pictures they take with their camera phones," said Philippe Quinio, marketing director of the imaging division at at STMicroelectronics.

More specifically, 7 billion images captured by mobile phones have never been uploaded or printed, said Rutie Adar, director of product marketing at CMOS imager developer TransChip Inc.

Many consumers never bother to learn how to move pictures out of their phones. Even those who figure it out assume the images are too low-quality to print.

Kodak draws a distinction between the camera phone and digital still camera by calling the former "a photo-capable device" and the latter "a photo-taking device." If current trends continue, "camera phones will become a niche product," said Nancy Carr, vice president of marketing for strategic relationships at Kodak's Consumer Digital Group. "You've got to make it right, or you let your opportunity pass by."

Usability concerns continue to dog the sector; camera phones still lack push-to-send and push-to-print capability, an issue for many consumers. And as the megapixel pressures mount for camera phones, picture quality will become a far more serious issue than it is today.

With advances in image sensor resolution, 2- or 3-megapixel image sensors are becoming the norm in midrange camera phones. That might lead consumers to conclude that the products are no longer mere toys. But a high-resolution sensor alone does not guarantee a better photo. Also imperative is a well-thought-out system-level design that can compensate for lens systems that remain mediocre.

"The reduction in pixel size to 2.2 microns and eventually to sub-2 microns obviously presents challenges in terms of [reduced] low-light sensitivity and an associated increase in noise and decrease in overall image quality," said Tony Henning, editor of Future Image Inc.'s Mobile Imaging Report. "A good sensor can still produce poor images if the lens is cheap or the raw data is mishandled."

At the heart of the issue lies the system-level design that manages the imaging flow. "Pixel technology, image sensor processor algorithms that can compensate for bad optics, and optimized specs for optics are the three fundamentals you need to own," said ST's Quinio. "Missing one [of the three] could be a problem."