Sharp’s 3D Camera for Mobile Devices Faces 3 Challenges

Sharp is dead-set on bringing 3D to mobile devices. The latest development in the company’s steady march towards the third dimension is a tiny 3D camera module for portable electronics.

The module consists of two cameras, each capable of recording 720p (1280 x 720 resolution) video, synchronized to capture a 3D image. It uses three different image processing methods to sync up both cameras: Color Synchronization Processing adjusts color and brightness, Timing Synchronization Processing ensures that the video signals from both cameras mesh together, and Optical Axis Control Processing corrects image positioning to produce the 3D effect. Sharp hasn’t said exactly how small the module is, but according to promotional photos it looks to be less than a centimeter tall and less than 4 centimeters wide.

3D video recording in portable devices has to address three major issues before it can be commercially feasible. First, these small devices have to have the processing power to both record and play back 3D video. Second, the camera has to be effective at multiple distances. Finally, the devices have to be able to display the 3D video they record. I’ll elaborate.

Processing power is an important issue for portable electronics. To capture 3D video, a 3D camera has to record twice as many frames as a 2D camera. 3D video works by providing a different image to each eye; while 2D video displays just one image at 24, 30, or 60 frames per second, 3D video has to produce two images at that same rate. For 3D video to look as smooth as 2D video, it has to effectively process 48, 60, or 120 frames per second. High-definition video requires even more power, because the individual frames are higher resolution. While this task is feasible for dedicated digital cameras and camcorders, it’s a tall demand for cell phones; currently, the HTC Evo is the only mobile phone that can capture 720p video, and that’s just in 2D. Besides the sheer power needed to process the video, 3D footage also requires twice as much space to hold it.

To really be useful, a camera has to be able to record video at different distances from the subject. Dedicated cameras can handle this task easily, because of fully-functional lenses that can physically adjust their focal length. Most camera phones, and presumably the Sharp 3D camera module, use a fixed-focal length lens that greatly limits its ability to adapt to different distances. 3D cameras introduce an entire new dimension to the problem; while 2D cameras only have to deal with focal length and subject distance to produce a clear image, 3D cameras have to adjust to produce the appropriate 3D effect, taking into account the parallax shift between the two camera components. Sharp has not yet explained how the very small camera module can overcome this problem, or at what range the 3D capture will be effective.

Even if a mobile device can record 3D video, it still has to be able to play it back. Typical 3D displays, like 3D-capable HDTVs, separate the images for each eye by displaying them both very rapidly and using glasses to split them up. The glasses either use passive polarized filters or active shutters to make sure the appropriate image reaches the appropriate eye to produce the 3D effect. Most users don’t want to carry around a pair of glasses larger than their own cell phones just to be able to watch 3D video on said phones.

Sharp is working on a 3D display that doesn’t need glasses, that would go hand-in-hand with the new 3D camera module. Instead of using glasses to separate the two images in front of the eyes, the display uses a device called a parallax barrier to separate the images directly in front of the LCD. The barrier uses a series of vertical slits to produce a slightly different image depending on where the eye is, like a “3D” lenticular comic book cover. Sharp has already unveiled a 3D eBook-reader that uses the technology, and the upcoming 3D-capable Nintendo 3DS portable game system will also incorporate Sharp’s parallax barrier.

Sharp isn’t the only company working on parallax barriers for 3D displays. Hitachi and Toshiba are both working on their own glasses-free 3D screens. If the companies are also working on their own portable 3D camera modules, we could see an all-out 3D device war in the next few years.


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