To begin with, you must understand the concept of a pixel. A digital photo is made up of millions of dots. Each dot is a pixel, and each pixel contains important information regarding the photo. For example, an eight megapixel image contains eight million pixels. Understanding megapixels involves much more than just knowing the number of pixels though. It seems like the more megapixels the better, right? This is not completely true.

A photo containing more megapixels will have a larger physical size. However, when viewed and printed at smaller sizes, a high megapixel photo and lower megapixel photo can be very difficult, if not impossible to tell apart. The main difference then is really the file size, the larger megapixel photo of course having a larger file size.

The larger file size means:

  • These photos take longer to transfer form memory cards
  • Fewer photos will fit onto memory cards
  • Your computer will process the larger files more slowly when editing, etc.
  • These photos must be drastically reduced in size to send by email
  • Uploading these larger images to web sites takes longer

The main advantage of a high megapixel image is that it can be printed at a larger size and maintain its clarity while a low megapixel image will lose clarity and sharpness when printed at large sizes. In fact, when you exceed the recommended print size for a given number of megapixels, the larger the print, the less clear the print looks. These days most digital cameras are at least 6 megapixel, so this only becomes an issue when printing larger than 9 x 12 inches.

Here are recommended megapixel requirements for large prints:

  • 6 megapixels for prints up to 9 x 12 inches
  • 8 megapixels for prints up to 11 x 14 inches
  • 10 megapixels for prints up to 12 x 16 inches
  • 12 megapixels for prints up to 16 x 20 inches
  • 14 megapixels for prints up to 18 x 24 inches

There is another important consideration regarding megapixels. You have more freedom to crop your photos when your photos are of higher megapixels. It is not really the cropping of the photos that is the concern, but rather enlarging the photos after they are cropped. When you crop a photo, you are eliminating megapixels. If you crop off 25% of an image, then you have eliminated 25% of the megapixels. Then, for example, your 8 megapixel photo is now a 6 megapixel photo,and you are more limited on how large you can make a nice, clear print.

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