Digital Camera Basics-Images

Posted on April 15, 2010, 11:03 pm

Over the last twenty years, most major technological breakthroughs in consumer electronics have been built around the same basic process: converting conventional analog information (represented by a fluctuating wave) into digital information (binary information represented by ones and zeros, or bits). This fundamental change in technology has changed the way we process visual information and sound – it has completely redefined what is possible. The digital camera is one of the most notable examples of this change because it is so different from its predecessor. Conventional cameras depend entirely on chemical and mechanical processes – you have no power whatsoever to make them work, except for a flash. On the other hand, all digital cameras have an integrated computer, and all images recorded electronically. The new approach has been a huge success. Since the film usually gives better image quality, digital cameras have not completely replaced conventional cameras. But as the digital imaging technology has improved and prices have plummeted, digital cameras have rapidly become more popular. In this article we will see exactly what is going on inside these amazing features digital age. Understanding BasicsLet you want to take a picture and send it by mail to a friend. To do this you need the image to be represented in the language that computers recognize – bits and bytes or binary information. Essentially, a digital image is a long series of 1s and 0s that represent all the little colored dots – or pixels – that collectively make up the image. If you want to get a picture in this form, you have two options: 1) You can take a picture using a conventional camera, then the film to a development lab that processes the film chemically, print it onto photographic paper, then place the image on a digital scanner to sample the print (record the pattern of light as a series of pixel values). 2) You can directly sample the original light that bounces off the subject, immediately breaking that light distribution in a series of pixel values – in other words, you can use a digital camera. At its most basic level, that’s all there is to a digital camera. Like a conventional camera, it has a series of lenses that focus light to create an image of a scene. But instead of focusing this light onto a piece of film is that it focuses on a semiconductor device drivers that records light electronically. A computer then breaks this electronic information to digital data. All the fun and interesting features of digital cameras are the direct result of this process. Instead of a film, a digital camera has a sensor that converts light into electrical charges. The image sensor employed by most digital cameras is a device Charge Coupled Device (CCD). Some cameras use semiconductor complementary metal oxide (CMOS) instead. The two CCD image sensors and CMOS cameras convert light into electrons. Without being too technical, a simplified way to think about these sensors is to think of a 2-dimentional array of thousands or millions of tiny solar cells. Once the sensor converts light into electrons, it reads the value (accumulated charge) of each cell in the image. Here the differences between the two types of sensors becomes a key factor: A CCD transports the charge across the chip and the bed in a corner table. An analog-digital converter (ADC) then turns the value of each pixel into a numerical value by measuring the amount of charge at each photosite and converting that measurement to binary form. CCD sensors create high-quality images with low noise. CCD sensors have been mass produced during a period of time longer, so they are more mature. They tend to have better quality pixels, and several of them. CMOS devices use several transistors at each pixel to amplify and move load using ordinary son. The CMOS signal is digital, so it needs no ADC. Because each pixel on a CMOS sensor has several transistors located next to it, the light sensitivity of a CMOS chip is lower (number of photons hitting the transistors instead of the photodiode.) CMOS sensors traditionally consume little power. CCD on the other hand, using a process that consumes lots of power. ResolutionThe amount of detail that the camera can capture is called the resolution, and it is measured in pixels. The more pixels a camera, the detail it can capture more and larger photos can be without becoming blurry or “grainy”. High-end consumer cameras can capture more than 12 million pixels. Some professional cameras support over 16 million pixels, or 20 million pixels for large format cameras. By comparison, Hewlett Packard believes that the quality of 35mm film is approximately 20 million pixels. Exhibition and FocusJust like a film, a digital camera to control the amount of light reaching the sensor. The two elements he uses to do this, the opening and shutter speed, are also present on conventional cameras. Aperture: The size of the opening of the camera. The aperture is automatic in most digital cameras, but some allow manual adjustment to give professionals and hobbyists more control over the final image. Shutter speed: The amount of time that light can pass through the opening. Unlike film, the light sensor in a digital camera can be reset electronically, digital cameras have a digital tier, therefore instead of a mechanical shutter. These two aspects work together to capture the amount of light needed to make a good image. In terms of photography, they have exposure sensor.