HOW THEY WORK : How the Digital Camera Works” (Cont’d)

As you may have realised in the last episode of “how digital cameras work”, we are not suggesting that, the digital cameras are superior to the conventional (film) cameras but are an upcoming phenomena. First of all, going by the fact that, we live in a computer (digital) age, everything we use is getting more and more related to the computer. The Digital Camera is not only about taking still photographs, no, it is about all forms of imaging. Here, we look at both still and motion pictures. This phenomenon of digitalising images is like a short cut, instead of making the images in a conventional way and then converting them into computer readable formats, is like doing the same thing twice. Moreover, in the conversion process, some data tends to get lost, corrupt or even degenerate in terms of quality; why not cut out these time consuming processes and produce the images directly in a digital format? Understanding the digital camera would enhance our understanding of the same because, virtually in many aspects of our life, there are several gadgets or devices employing this technology, e.g. Digital Video Camcorders, Surveillance Cameras, Mobile Phone Cameras, Traffic control Cameras, etcetera. As earlier on stated, these devices are built with a digital storage or memory that is permanent, they capture and store the data in form of “bits”, a bit is a numeric representation of data in form of zeros and ones. The zeros represent the absence of a charge whereas the ones represent the presence of a charge. In brief, zeros store negative polarity whereas ones store the positive polarity. One thing to note is that, the previous cameras were manual in that, they comprised a film and this film had to be manually wound (exposure by exposure) after the operater had taken a photo, so that the used part of the film was safeguarded. Then came the electronic cameras that had a motor that wound the film; it is important to note that, though it was automated, it wasn’t digital. The cameras only became digital when they were built with a miniature microprocessor that converts the temporary image into bits and bytes (binary notation or base two) and then have them stored in form of electric charges on a digital storage media like memory cards or flash disks, etc; basically, the digital camera is just like a conventional camera, it has a series of lenses that focus light to create an image of an object. Instead of focusing this light onto a film, it focuses it onto a semiconductor device that records light electronically. A microprocessor then breaks this electronic information down into numeric data. All the features of digital cameras come as a result of this kind of process. Instead of film, a digital camera has a sensor that converts light into electrical charges. The image sensor employed by most digital cameras is a “charge coupled device” (CCD). Some cameras use complementary metal oxide semiconductor (CMOS) technology instead. Both CCD and CMOS image sensors convert light into electrons. These work much in the same way as the Solar Panels, they capture light and convert it into electrons; once the sensor converts the light into electrons, it reads the value (accumulated charge) of each cell in the image. This is where the differences between the two main sensor types set in. A CCD transports the charge across the chip and reads it at one corner of the array. An analog-to-digital converter (ADC) then turns each pixel’s value into a digital value by measuring the amount of charge at each hotosite and converting that measurement to binary form. CMOS devices use several transistors at each pixel to amplify and move the charge using more traditional wires. eddie@afrowebs.com