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What is resolution

By Charles Hopkins Published 07/6/2006 | Arts and Culture

One of the key terms in digital photography is resolution. It denotes the quality of an image. An image with a low resolution is considered a poor quality picture while a picture with high resolution is characterized as a good quality picture.

To understand resolution, it is important to understand the role of pixels. Pixels are the smallest conceivable dots that can store color. When the pixels are spread sparsely across a picture then the picture is said to have low resolution. But when every inch of a picture is packed with pixels then it is called a high resolution picture.

The digital cameras use the term megapixels to establish the resolution of an image. One megapixel is nothing else but the equivalent of a million pixels. A photograph taken by a one megapixel camera has one million pixels. Similarly, a camera that can take a photograph with ten million pixels is called a 10 megapixels camera.

Quite clearly, the higher the resolution of a camera as expressed in megapixels -- the sharper is the image. In fact, professional photographers use 14 megapixel or 22 megapixel cameras, because they know that their pictures have to go for commercial printing.

The advantage of these pictures is that they are sharp and can be printed easily. They are not like the pictures taken from a 1 megapixel camera that can be best printed in 4 by 6 prints. Instead they can be used to make a full length banner without losing any sharpness or clarity.

There is also no need for photographers to artificially boost the pixel level. This happens often with low resolution pictures. The photographers add pixels through a process that is known as interpolation. They do so by assigning an intermediate color to the added pixels, so that they can easily merge with the color of the existing pixels and no one can say that the picture has been manipulated.

However, this process has a limitation. It can add to resolution, but it cannot improve clarity. Still people go ahead with interpolation without realizing that they cannot achieve the right results with this kind of approach.

Resolution is not a problem on the net. Web designers from the beginning have insisted on keeping the resolution of Internet pictures low. Their argument has been simple: a high resolution picture slows the download of the picture. This is because such a picture needs a large bandwidth pipe to travel from the server to the user's monitor. In contrast, the low resolution pictures download much faster.

Given this fact, web designers insist that the resolution of images meant for the net should be kept at 72 ppi -- that is 72 pixels per inch. Pictures with a 72 ppi resolution look sharp on a computer screen.

Also, when it comes to printing a digital image, it is the high resolution pictures that print best. These pictures can also be printed in large sizes. But pictures with low resolution cannot be printed in a big size. They end up looking weak and hazy.