Basic Principle of digital cameras
how digital camera works
How a digital camera works
The word photography comes from the Greek words ‘photos’ means light combined with the word graphis means drawings which gives a sense that to draw with light. Simply we can say photography is the technique of recording fix images on a light sensitive surface. ‘Light sensitive surface’ this phrase differentiate analogue and digital cameras. In analogue cameras this light sensitive surface is a film coated with chemical substances that are sensitive to the light; in contrast digital camera uses sensors to process image and stores it in digital files. Construction and mode of function of a digital camera varies from their type to type but the basic principle of taking image is all the same. Here I discuss a little about construction and basic working principle of a primitive digital camera.
A digital camera consists of the following basic parts:
· Lenses: It focuses the image, refracting the light rays comes from the object so that they converge into a coherent image.
· Diaphragm: It determines the amount light enters through the lenses. It measures as f-number, the greater the f-number the smaller the opening of the diaphragm.
· Shutter: It determines the amount of time of exposure. It is measured in fractions of a second. The faster the shutter the smaller the exposure.
· CCD (Charge Coupled Device): These are a group of sensors that converts light into corresponding electric charge. Sensors are made of light sensitive diodes called photosites that convert photons into electrons (electric charges). The amount of photons exposed by these photosites produce proportional amount of charges. CCD also includes filters that generate a color images, a series of filter must unpack the image into discrete values of Red, Green and Blue (RGB).
Essentially these are the basic components of a digital camera, since we intend to discuss only the basic principle so we do not wish to go into deep more.
Working principle of a digital camera:
· Capturing image: lenses focused the light rays come from the object made into a coherent image. Diaphragm determines amount of light to be entered and shutter speed determines time of exposure. Then lights made fall onto sensor (CCD) to get corresponding electric charge.
· Binary system processing: Where there is word digital, the word binary also found there. To convert analogue signal (electric charge from photosites) to Digital signal in binary form a ADC converter is used. Each of the charge stored in photosites assigns to a binary value, storing them as pixels. A pixel is a point sample of an image which contains three basic color (RGB) components. Pixel per square inches determines the resolution of the camera, which indicates the size and quality of image. In next post I’ll discuss more about pixel and resolution.
· Compression and storage: Once the image is digitalized, it is compressed by a microprocessor and stores as image file (JPEG, TTF etc.)
From the age of invention of camera, evolution of this has been taken place and which will continue. Now digital cameras are being developed by adding new features like video recording, music playing, even GPS has embedded in it.