When you take a picture with a digital camera the light strikes a digital sensor array, instead of a piece of film. These digital sensors are computer "chips" with names like CCD, CMOS, Foveon, or others. They take the place of a piece of film that must be moved across the focal plane of the camera. The digital sensor is made of millions of tiny sensor points called "pixels," which is short for "picture elements." They are laid out in an array with rows and columns, like in a computer spreadsheet or wall calendar. For instance, my camera has an array of sensors in its CCD that is 3008 horizontally, and 2000 pixels vertically (3008x2000). If you do a simple mathematical formula on the pixel array size you will come up with the "Megapixel" rating of the camera. This is the number that most manufacturers use to sell the camera. The simple formula 3008x2000 = 6,016,000 shows that my camera has over six million pixels, or is a "six megapixel" camera.

Let's knowing more about CCD & CMOS :

CCD

Charge-Coupled Device (CCD), sensitive electronic device that stores packets of information as electric charge. Because of their versatility in storing charge, CCDs are often used as analog-to-digital and digital-to-analog converters and signal scramblers, but their main function is recoding information about light hitting the surface of the CCD to create light images electronically.

A CCD used for recording visual information is made of an array of photodiodes (devices that conduct electricity when light strikes them) on top of a semiconductor (a material that conducts electricity better than electrical insulators but not as well as electrical conductors). When light strikes a photodiode, an electric current proportional to the amount of light is sent to a capacitor, which stores the charge. The semiconductor processes the signal from the capacitor and sends it to a computer or other device that can analyze the data about the light that hit the CCD.

CCDs are used in facsimile machines, photocopiers (see Xerography), bar-code readers, and cameras. In astronomy CCDs have almost completely replaced photographic film as an image-capturing method. A CCD is about a hundred times more sensitive to light than photographic film or a photographic plate. The signal from a CCD is also easier than a photographic image to convert into digital code for storage in a computer.

CMOS

CMOS (complementary metal-oxide semiconductor) is the semiconductor technology used in the transistors that are manufactured into most of today's computer microchips. Semiconductors are made of silicon and germanium, materials which "sort of" conduct electricity, but not enthusiastically. Areas of these materials that are "doped" by adding impurities become full-scale conductors of either extra electrons with a negative charge (N-type transistors) or of positive charge carriers (P-type transistors). In CMOS technology, both kinds of transistors are used in a complementary way to form a current gate that forms an effective means of electrical control. CMOS transistors use almost no power when not needed. As the current direction changes more rapidly, however, the transistors become hot. This characteristic tends to limit the speed at which microprocessors can operate.

A semiconductor device that consists of two metal-oxide semiconductor field effect transistors (MOSFETs), one N-type and one P-type, integrated on a single silicon chip. Generally used for RAM and switching applications, these devices have very high speed and extremely low power consumption. They are, however, easily damaged by static electricity

DIGITAL CAMERA RESOURCE :

Digital camera file formats Most digital cameras record files in JPEG format (they have a .jpg filename extension), but they use a special variation of JPEG called Exif. This is a standard that allows extra information t... Read more

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