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Digital Imaging

In the same way that fine grain produces better quality photos, so fine pixels and “bit depth” create more detailed images. By measuring the dimensions of a picture by its pixel count we can gauge its shape, size – and as a result – its quality. A picture that measures 200 pixels by 200 pixels, for example, has 40,000 pixels in the image. If another image measures 400 pixels by 400 pixels, the 160,000 would make the image sharper because there are more densely populated pixels within the space of the photograph. You could say that the second has a higher resolution.

The physical size of the image depends on the size at which these pixels are displayed. Most web images are shown at 72 dots per inch (dpi). An image at 300 x 200 dpi would be just over 3 inches wide and slightly under 2 inches high when shown at full resolution. For photo quality prints, the bare minimum resolution is 300 dpi.

You can check with the manufacturer of your camera to see the maximum number of mega-pixels your camera holds (this is often featured on the box your camera came in). Every mega-pixel is equal to 1,000,000 pixels, so if your camera is a 2 mega-pixel camera, the image will have 2,000,000 pixels at its highest resolution output. Most professional cameras have a mega-pixel count of 2.1 mega-pixels or higher. Anything from 5-8 mega-pixels is considered very good, but there are now cameras being made to have 14-20 mega-pixels. A good rule to remember is not to overload your images; it is not necessary to pay thousands of dollars for 20 mega-pixel camera to make 5x7 prints. The higher the pixel count usually means the more room you have to increase the size of your image. Try not to be wowed by mega-pixel count (which is what manufacturer’s use to lure amateurs into buying professional cameras). You can produce a very good 8x10 print with a 2.1 mega-pixel camera.

When an image is taken, the data must be stored so it can be read easily. Its method of storage is known as its file format.  There are a number of file formats, each recording essentially the same data but using different codes to do so. These codes are often dependant on the size and resolution of the image. Mac and PC both have the following file formats that recognize an image: TIFF, PICT, BMP, JPEG, GIF and EPS.

Image files take up a lot of space on your computer – more than any other kind of file – and the higher the resolution, the more space it will take up. This can result in your computer taking a long time to perform a task. It is best to equip yourself with a computer with a fast processor, but if you are truly serious about photography storage and editing, your best bet is to purchase a Mac computer rather than PC. In short, Mac’s are better suited for graphic design and digital imaging. Mac’s are more expensive than PC’s but not much more expensive than the best PC brands out there. The new Mac G5 flat screen is the leading Mac computer today, but you can purchase a G2 or G3 for a lot cheaper and still have a better processor than the newest PC.