Electronic imaging grows closer to commodity status every day. Arguably we're already there in certain device categories; to wit, cameras now have a home in 30 to 40 percent of the 700 million some-odd wireless handsets shipped annually. In short, imaging is now a game of big numbers, big volumes and big money.
Looking at more imaging-centric devices, the list of Asian-produced products runs long, with dozens of manufacturers in China and Taiwan cranking out and rebranding basic-function digital cameras ranging from key-chain novelties to quite-capable systems. Barring charge-coupled-device-based film-replacement digital still cameras, most of these mid- and lower-tier products are priced at $125 or less.
One of several examples of the breed, the DV4000 from Mustek of Taiwan, is a digital camcorder, a digital still camera, a digital voice recorder, an MP3 player, a Secure Digital/Multimedia Card (SD/MMC) memory card reader and a PC camera, all in a compact package measuring about 3.5 x 2.5 by 1.25 inches. The camera interfaces to a host computer via an industry-standard USB port, and the street price hovers in the range of $100 to $120. Photos and movies are recorded to the included memory card, yet the product's design is clearly intended to mimic more traditional tape-based camcorders with a flip-out LCD screen and palmable camera body. Familiarity of form, after all, is a powerful tool in selling a product.
Electronics in the unit are contained on three rigid printed-circuit boards fabricated with standard through-hole technology, while interconnects between the boards and the display are accomplished using polyimide flex circuits inserted into zero-insertion-force connectors.
Based on a half-inch optical-format Omnivision 2-megapixel CMOS sensor, the recorded resolution of the DV4000 gets notched downward for movie capture. Using subsampling and pixel combining in the sensor, video is recorded at 30 frames/second using 320 x 240 resolution or at 640 x 480 resolution with a drop to 10 frames/second. All video is stored in MPEG-4 format.
Estimation technique
Going the other direction in still-camera mode, the design up-interpolates the 2-Mpixel native sensor resolution to 4 Mpixels recorded. Using a TCatch image processor ASIC from Sunplus (also of Taiwan), the DV4000 employs estimation techniques to double the number of pixels for stored still images.
Looking at the "real" pixels, the processor guesses at appropriate color and luminosity information for the "artificial" pixels-a technique that improves image quality but can be a problem at the boundaries of color or sharp contrast variation, or both. Those familiar with imaging will see parallels between this up-interpolation and the demosaicing that occurs at the sensor level in forming the initial image from the native pixels. A Google search with the term "demosaicing" will prove useful to the technically curious.
The TCatch device is supported by 1 Mbyte of NOR flash memory from Fujitsu Semiconductor (29LV800BA) for code storage and 16 Mbytes of SDRAM from Hynix (HY57V281620HCT) for working memory. Additional off-board storage is provided by a 32-Mbyte SD/MMC card. Supplied with the product, its memory capacity can be expanded to 256 Mbytes. A 1.5-inch low-temperature polysilicon thin-film transistor (TFT) LCD serves as the viewfinder and allows image preview/review. Backlighting for the display is provided by two white LEDs.
We note that there is no dedicated power-management chip, and it was observed that power consumption for the unit is a measured 1.5 to 2 watts no matter what the mode of camera operation. This suggests a less-than-miserly electronics design.
The F2.8 aperture four-element glass lens of the DV4000 design can switch focus lengths between macro capability (about 12 to 27 inches) and normal (27 inches to infinity). Additionally, the product features a 4x digital zoom that-while inferior to a true optical zoom-reduces cost and space requirements to maintain the compact form factor of the unit.
In contrast to the up-interpolation, digital zoom works in the opposite direction, simply subsampling the captured photo and expanding the selected subwindow to give the illusion of a zoomed image.
All this imaging trickery points to the fact that high-resolution sensors and complex zoom optics tend to add cost more than image processing, where the latter is somewhere between cheap and free. With a low target price point for the product and a cost of goods sold that is pushing 50 percent of price, the inexpensive-but not necessarily highest-quality-design approach rules the day.
Assuming much larger storage and better optics, it is possible to imagine that future iterations of this type of product could begin to supplant the tape-based camcorder. Additionally, the Mustek product illustrates the ongoing objective of integrating high-resolution still and lower-resolution motion image capture in a common platform. While neither goal was fully realized with the DV4000, the design shows how software and DSP combinations are trying to offset some of the hardware limitations driven by tight budgets for the bill of materials.
So, what goes with imaging? Well, storage and processing, of course, and the latest in that realm can be summarized in two words: Mac Mini. While the migration of Apple to Intel processors portends an interesting future for that platform, the Mac mini is a feat unto itself. More on that can be found at www.teardown.com.
David Carey, president of Portelligent. The Austin, Texas-based company produces teardown reports and related industry research on wireless, mobile and personal electronics (www.teardown.com).
See related chart
