Pixel Counts Don’t Really Add Up

aNewDomain.net — When digital cameras first appeared, it was all about megapixels. A 3-megapixel camera was better than a 1- or 2-megapixel camera. Much of how you decided what to purchase had to do with pixel count. This method of determining the quality of a digital camera is ingrained in the minds of consumers. Unfortunately, it is also still used to sell digital cameras.

It is, however, no longer valid. Actually, as megapixel counts have increased, their importance has decreased.

To understand this, you need a little background about pixels. A pixel is the basic unit of a digital image. You can think of pixels as a cluster of colored dots that combine to form images in a digital camera, on the computer screen, or on a printed page. The camera captures the image, which is made up of pixels, with its image sensor and records it on its internal memory or a memory card. The more megapixels a camera can handle, the greater the amount of information it can record.

Theoretically, the more pixels that the camera has, the greater the image resolution should be and therefore — the higher the image quality and sharper the pictures. This is why everyone thinks that the number of megapixels is so important. Yet, this is not always true because all of the megapixels must fit on the camera’s sensor (shown below).

Mega Pixel CCD sensor

Source: Wikimedia Commons



Camera sensors come in many different sizes. Simply put, if a high number of pixels is put on a small sensor, the pixels themselves must be smaller. Also the size of the sensor determines how much light the camera can bring in and the pixels can only capture the image when exposed to light.

Smaller pixels decrease the amount of light collected by each pixel and result in more noise in the image. Noise is the presence of specks of color that don’t belong in the photograph. So high megapixel counts on a small sensor may actually result in a degradation of the quality of the photos, making the image worse instead of better.

Printing also comes into play when we talk about megapixels. A higher megapixel count does mean that you’ll be able to print out images at a larger size without losing resolution. The following table gives you an idea of how the megapixels translate into printing. This number will vary depending on the way the megapixels are counted, on the aspect ratio, and on the dots per inch (dpi) of the printer. But this will give you a rough idea of the number of pixels needed for photo printing and commercial quality printing (300 dpi).

Megapixels Print Size at 300 ppi in Inches
3 5” x 7”
7 8” x 10”
14 11” x 14”

Higher megapixel counts also allow you to crop a part of the image and print or display the cropped area without losing resolution.

So while megapixels do count, no one should judge the quality of a digital camera only on the number of megapixels. You should also look at the sensor, lens, hardware quality, interface, special features, and controls. Remember, more megapixels aren’t necessarily an indicator of better image quality, especially on small-sensor cameras.

Based in Pinehurst, North Carolina, Sandy Berger is a veteran tech journalist and senior editor at aNewDomain.net covering tech tips and tricks, apps and gadgets in general. Email her at [email protected]. Follow her on Twitter @sandyberger, +SandyBerger on Google+, and www.facebook.com/sandyberger on Facebook.

Jeremy Lesniak
Based in Vermont, Jeremy Lesniak is managing editor at aNewDomain.net and founder of Vermont Computing, Inc. and whistlekick.com. Email him [email protected]
Jeremy Lesniak
Jeremy Lesniak
Tags: Gadgets & Devices