What is a CCD?
A CCD is the "electronic eye" of a digital camera. It's a semiconductor chip made of millions of tiny, light sensitive squares arranged in a grid pattern. These squares are called pixels . Good cameras use CCDs with many more pixels and this is why cameras are compared by how many megapixels (millions of pixels) they have. A camera rated as having 6 megapixels has 6million pixels in... its CCD—probably arrangedin a rectangle with three thousand across and two thousand down (3000 x 2000 = 6 million). A better camera rated at 12 megapixels would have a 4000 x 3000 pixelCD. Take a photo the same size with those two cameras and the 12 megapixel one is going to give you 1000 more dots horizontally and 1000 more vertically—smaller dots giving more detail and higher resolution . A single pixel in a CCD is something like 10 micrometers (10μm) in diameter (5–10 times smaller than the diameter of a typical human hair)!
>How charge-coupled devices (CCDs) work<
When you take a digital photo, light from the thing you are photographing zooms into the camera lens. This incoming"picture" hits the CCD, which breaks it up into individual pixels. The CCD measures how much light is arriving at each pixel. This information is turned into a number that can be stored on a memory chip inside the camera. Thus, taking a digital photograph converts the picture you see into a very long string of numbers. Each number describes one pixel in the image—how bright or dark and what color it is.
Step by step
1. Light from the object (in this case, a bicycle) enters the camera lens.
2. The CCD inside the camera splits the image up into millions of pixels (squares).An LCD display on the back of the camera shows you the image that the CCD is capturing—not an image of the object seen through a series of lenses (as with aconventional camera), but a redrawn, computerized version of the original object displayed on a screen.
3. The CCD measures the color and brightness of each pixel.
4. The color and brightness are stored as binary numbers (patterns of zeros and ones) in the camera's memory card. When you connect your camera to a computer, these numbers are transmitted instantly down the wire.