ISSN: 1391 - 0531
Sunday September 16, 2007
Vol. 42 - No 16

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Digital electronics are creeping into more and more of the everyday gadgets and tools we use and it has already taken over everything from typewriters to alarm clocks. Modern car engines and even their brake systems are synchronized and manipulated by computer chips. In less than a decade, digital cameras have all but completely replaced their analogue ancestors, and thus it is worth exploring the digital take-over of our tools. As much has been discussed about the bulky machines sitting on desktops, we know little about how to get the most of our digital cameras, or how computers in modern cars actually work. This week, we'll start off by exploring digital photography, how it works, its strengths and weaknesses, what to look for when you buy a digital camera and then how to get the most of it.

It is almost intuitive that digital cameras should have light sensitive sensors inside them to capture images. In fact the number of light sensitive sensors is perhaps the most prominent feature in any given digital camera and is almost always denoted as "mega pixels." A '5 mega' pixel camera for example has roughly five million light sensors near the focal point of its main lens. It is reasonable to think that each of these sensors captures the portion of the image that falls on to it and they all combine to recreate the full picture.

It is tempting to think that when a digital camera captures an image, what it records is absolutely what is in front of it, but this is not quite accurate. Each sensor captures a figment of light that falls on it and it takes a significant amount of processing to weave each of those tiny pixels together and recreate – in most cases – an approximation of the actual image that was captured. As a result, until recently, most digital cameras suffered from a lengthy delay between shots because you could not take another picture until the previous one had been processed – which often took a couple of seconds. The newer cameras simply do this processing faster thanks to faster processors.

Another detail that most camera manufacturers would like to brush aside about a camera's mega pixel rating is that a digital camera with a 6 mega pixel rating doesn't actually have six million "pixels" in the true definition of the word, but six million sub-pixels. True enough that there are six million photo-receptive sensors, but while a "pixel" actually refers to a point in the picture that has full colour information, each photo receptive sensor in the camera has a filter which only lets in one of the three primary colours. The image processor then guesses the intensity of the other two colours for that "pixel," based on their intensity recorded by the neighboring photo receptors.

Images that are produced by a digital camera are often "soft" – the edges of objects in the picture are poorly defined and there appears to be a white haze over the image. This is a result of a combination of limitations including the cameras optics, the way light is converted into electrical signals by the sensor and how the sensors and the optics interact with each other. To overcome these effects, most camera manufacturers include a software processing technique called "sharpening" which a user of any graphics processing software would be familiar with.

Next week, we will continue our discussion about digital photography including how to tweak the different settings on your camera to get the best quality pictures, and also how you can enhance the quality of your digital photographs by using a few steps using a computer. In the meantime, do write in to with all your questions and comments.

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