The Gadgets Page

January 20, 2004

Understanding Resolution in Digital Cameras

Filed under: Articles,Cameras — Michael Moncur @ 1:28 am

Resolution is one of the most important factors to consider when you purchase a digital camera. If you already own one, you can choose different resolutions when shooting pictures. This article is a basic guide to camera resolution and how to choose the correct resolution for different needs.

What is Resolution?

The resolution of a digital image is a measure of how much detail it contains. This ranges from the low-resolution images you find on Web sites and TV to the high-resolution, detailed images that are used in printing books, magazines, and posters.

A pixel is a single bit of data–a colored dot–that makes up a portion of a digital image. Digital cameras typically measure resolution in megapixels, or approximate millions of pixels. Today’s low-end digital cameras are typically two megapixel: 1600 x 1200 pixels, or exactly 1,920,000 pixels.

MegapixelsActual ResolutionPrint Size
21600 x 12005 x 7 inches
32048 x 15368 x 10 inches
42272 x 17049 x 12 inches
52592 x 194410 x 13 inches

Choosing a Resolution for Printing

The table above lists the maximum size of print you could make, at a reasonably high quality, for each resolution. In practice, you may be able to make acceptable-quality prints at larger sizes, depending on your printer or printing service. Your standards for a printed image are also important: images for a published book or an art exhibit will require more attention to detail than those for casual display.

Print resolution is usually measured in dots per inch, or DPI. The print sizes in the table allow for 150 DPI printing, which is sufficient for most printers and printing services. If you have a lower resolution, the print will have fewer dots per inch, which results in a blocky appearance.

Zooming and Cropping

If two megapixels is more than enough for your printing or display needs, why shoot at a higher resolution? One answer comes when you think of a high-resolution picture as a combination of low-resolution pictures. In other words, having more pixels gives you more options for zooming, cropping, or framing the shot.

For example, if you have a five-megapixel (2560 x 1920) image, you can cut off up to 960 pixels off the sides and up to 720 pixels off the top or bottom to make a 2-megapixel picture. This lets you zoom in on the important part of the picture, or center it differently.

  • Note: The "digital zoom" feature on digital cameras is nothing more than an automated version of this process–the image is cropped, then enlarged to the full resolution, but you don’t gain any detail. You may find it more useful to crop images yourself.

Images for The Web

Most computer screens have a maximum resolution of 1600 x 1200–equivalent to a 2-megapixel digital camera image. Most users use even lower resolutions, with 800 x 600 and 1024 x 768 being the most common.

Thus, if your primary use for a digital camera is to publish images on the Web rather than in print, your resolution needs will be lower. Much lower, in fact–unless your site deals with photography, you will typically be using images much smaller than 800 x 600.

As with printing, shooting at a higher resolution will give you more options for zooming, cropping, and framing your pictures for use on the Web.

Conclusion

What resolution you need for a digital picture depends on what you plan to do with it. You’ll need a high resolution for printing, depending on the size and quality you need, but resolution is less important for web images. Having higher resolution can also make it easier to crop or reframe pictures.

Obviously, when you choose a camera, the higher the resolution, the better–but if two or three megapixels is sufficient for your needs, save your money for more important things.

3 Comments

  1. Great stuff, this is very informative

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  3. This is where the resolution comes in and the number of megapixels your digital camera offers begins to matter. The photographer’s rule of thumb is buy as many megapixels as you can afford.

    Comment by jump manual — March 11, 2011 @ 6:10 am

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