How It Works: The Thinnest Camera

Here’s how pocket-size digital cameras pull off a huge feat: turning six million bits of light into a photo in barely a second

Specs: Casio EX S600BE

What: Thinnest 6-megapixel camera available

Size: 2.32 in. (h) x 3.54 in. (w) x 0.63 in. (d)

Weight: 4 ounces

Cost: $400

Sensor: 0.4-inch-square primary-color CCD containing 6.18 million pixels

1. Focus
The lens element comprises many tiny lenses stacked on top of one another. They lie together tightly when the camera is off, but a small motor extends them when you turn it on and when you adjust the zoom. The lenses work in tandem to precisely gather and focus light onto the image sensor as directly as possible. If light hits at an oblique angle, the sensor won´t record it properly, and your shot will be fuzzy. No matter how advanced the rest of the camera, a shoddy lens will always make shoddy pictures.

2. Record
Mounted directly behind the lens, the CCD (charge-coupled device) sensor is a rectangular array of millions of individual light-sensitive photo sites-one for each pixel-that translate photons into electrical charges. Another very small lens is mounted over each photo site, along with a red, green or blue filter, which determines the color of the light. Each pixel´s electrical energy is tallied row by row and moved into the analog/digital converter, which changes it into a digital signal of 0s and 1s.

3. Process
Never mind the number of pixels-if the information coming from them isn´t processed correctly, your image will suffer. The digital-signal processor (DSP) refers to both the circuitry and the software that applies the camera´s instructions to the recently arrived digital data and then assembles an image. After you snap a picture, the DSP examines each pixel´s color value in relation to the values of its neighboring pixels to accurately determine its true hue. For example, if a red pixel is very bright and all the green and blue values near it are also very bright, then it´s most likely a white pixel. The DSPalso gathers information before you press the shutter and uses that to more accurately process the image.

4. Display
The Casio´s LCD is a typical thin-film transistor (TFT) display that sandwiches a rectangular arrangement of thousands of red, green and blue pixels beneath layers of liquid crystals and multiple layers of glass. The image information arrives here from the DSP, so you can immediately review it.

5. Save
A flash-memory card, like the SD card in the Casio, stores data in a system of gated transistors called cells, which are opened and activated by the voltage of the signal from the DSP. Denser cells mean more memory. A six-megapixel photo uses about two megabytes of memory.

Tip: Steady On
Smaller cams are even harder to hold steady. Many now include digital optical stabilization, in which the DSP looks for the telltale signs of a shaky shot and tries to fix the jittered pixels. Still, nothing beats using a tripod.