Digital Camera

In a world that's moving so fast into everything digital, how could cameras get left behind? Then along came the digital camera in a wave that swept over the whole world. How exactly does it differ from the traditional camera? Up to the point when the image is captured, the process is the same in both. You have a lens, a shutter and an aperture. The lens focuses the image, the shutter lets in the light and the aperture controls the light that is let in. There the similarity ends. While traditional cameras capture images on film, the digital cameras image is captured by an electronic image sensor.

What exactly are image sensors? The most often-used and probably the most efficient one is the Charge-Coupled Device or CCD. The other sensors available are the CMOS and Foveon. The sensor is actually a mass of photosites or electrodes to measure the intensity of light. Each one becomes a pixel in the image that takes shape. This is how a camera's resolution is measured - by the number of millions of pixels or mega pixels it has. These image sensors convert light into electrical signals which then go into an A/D or analog/digital converter, then into binary numbers and then into the memory card. All this is done in the little computer within the camera.

Since these photosites only measure light, filters are needed to supply the color. So there are filters consisting of the three primary colors, with more of green as the eye is more sensitive to this color. So you'll find green following red and then following blue in the arrangement of these filters on the image sensor. In order for the picture to take shape, each photosite which just has one color is analyzed and the color calculated. The color can only be analyzed after taking into account the surrounding colors. This complex process is called demosaicing. The image then goes through the camera settings for light, color and contrast and is then stored in a JPEG format on the memory card. This is a compressed format and any excess data is deleted. Certain cameras do allow pictures to be stored as raw data. Even data before the demosaicing stage is stored. This is very useful if you want to transfer it onto a computer and edit it with software specially meant for this purpose. Given this data, there can be a great deal of control over the pictures using the relevant software on the computer.

To read more about digital photography visit Jill Kane's site at http://www.digital-photography-help.com

Written by: Jill Kane

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