Megapixels for the masses!

Question

What is a megapixel and what does it mean for your pictures?

Answer

This question was answered on January 6, 2005. Much of the information contained herein may have changed since posting.

So what is a megapixel and what does it mean for your camera? Well, let’s start be defining a pixel. A pixel is an abbreviation of the term ‘picture element’. It can be likened to a single fiber of a fabric; individually it is too small to be noticed, but together they make up all digital images.

The ‘mega’ in a megapixel simply means a million pixels. So if your digital camera is rated at 2 megapixels, it can take pictures comprised of up to 2 million pixels. That’s a lot of pixels you say? Well, yes; but the more you fit into an image, the larger it can be printed and the better it’s going to look.

Really the biggest determining factor as to how many megapixels you need is based on how big you intend to print the pictures. A printer’s print quality is rated in DPI (Dots Per Inch) or the number of pixels on a one inch line of paper. This is called the printer’s resolution. A “photo quality” printer will print at least 200 DPI, though photo quality is considered 300 DPI. Again, the more pixels you squeeze into an area the sharper and larger is can be printed.

For instance, let’s say the largest you ever intend to print pictures is 4x6. Multiply the picture length by the resolution you intend to print (we’ll say 200 DPI), and then do the same with the width. Now multiply those two results. Confused? Here’s what it would look like:

4 (length) x 200 DPI (resolution) = 800

6 (width) x 200 DPI (resolution) = 1200

So, to print a 4x6 picture at 200 DPI you need to capture an image that’s 800 pixels long and 1200 wide. So how many megapixels does your camera need to capture? Multiply the two results above:

800 x 1200 = 960,000 (not even a single megapixel)

So now we know a 1 megapixel camera (capable of capturing up to 1,000,000 pixels per image) is more than enough to print 4x6’s at 200 DPI. What’s that you say? You want to print at 300 DPI? After crunching the numbers again you’ll discover a 2.2 megapixel camera will be needed to print those 4x6 images. An 8 MP (megapixel) camera won’t be able to print a 4x6 any better than the 2.2 MP.

Here are a couple charts to simplify things:

Printing at 200 DPI

Printing at 300 DPI

While the number of megapixels determines how large you can print pictures, there are other factors that determine the quality and sharpness of the images. The lens and light sensor have a huge impact on the overall quality of your snapshots. Stick with a name brand and you should be okay. Canon, Nikon, and Olympus are big names in the photography arena and aren’t likely to lead you astray.

So, depending on what you intend to do with this camera don’t spend too much money on something you’ll never use. Good luck and have fun!

Author

Posted by Chad of Data Doctors on January 6, 2005