Friday, May 25, 2007

Camera-Phone System Partitioning Issues

EDN publishes an article on camera-phone system partitioning considerations. The article discuss various ideas, like Micron's camera shake compensation:

“A high-end DSC may have several frame buffers for different functions,” says Sandor Barna, director of strategy and planning at Micron Technology’s imaging operation. “But without that kind of memory space, you have to use algorithms that make decisions based on statistics you’ve collected over a few previous frames.” Barna says that such algorithms can be ingenious. “For instance, with a frame buffer you can do quite sophisticated correction for camera shake. Without it, you can still monitor the data stream for motion and capture the image at an instant when the motion is least. Or, you can just recognize that camera shake is going to be an issue and increase the shutter speed.”

“Some OEMs just want to feed in power and clock and get back files,” says Michael de Luca, marketing manager at Kodak. “But some of that may just be immaturity in the market. In principle, there is probably a best partitioning for a given set of end-user needs, and it requires some involvement by the phone manufacturer.”

Still, there are some natural IP groupings. For instance, virtually everyone acknowledges that sensor manufacturers should perform corrective processing and data conversion to generate digital raw-pixel data because they know the peculiarities of their sensors. After that stage, things become complicated, however.

Tessera Director of Technical Strategy Christopher Aubuchon explains that there are many approaches to EDOF implementation, trading off lens complexity for computational demands for image quality. It is possible to end up with a very demanding lens design, large computational requirements, or seriously compromised image SNR. It is also possible to find a local optimum that matches the needs of a particular OEM.

“There is not much motivation for a high-end DSC or even high-end-handset manufacturer to eliminate mechanical focus,” admits Tessera’s vice president of corporate development, John Keating. “But in the midrange—feature phones, for example—where image quality is important but a very small module is equally important—there is fertile ground for this technology. In the long run, I think you will see EDOF penetrate some of the DSC market, as well.” Each of these markets may use a different lens design with a different image-reconstruction algorithm.

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