People wonder why their digital photos are so large in file size, super slow to print or upload, or why when they add it to a Powerpoint file, their Powerpoint file ends up being humongous.
Let's start with some definitions.
Megapixels or MP = amount of pixels in millions in a digital image also known as resolution.
Resolution = dimensions of the image in pixels, so Width x Height. The higher the resolution, the more pixels fit in that image and the larger the image will be.
So you're probably thinking that the higher the resolution the higher the quality of the image? Well, this is true but only in extreme cases, for example if you were printing out wall sized images or billboards. For a fixed size display, higher megapixels do not absolutely mean higher quality.
For example, an average computer LCD screen at 19 inches runs at a resolution of 1600 x 1200 or about 2 megapixels. If you take a picture at 4 megapixels <2304 x 1728> and view them on your LCD that runs at 2 megapixels <1600 x 1200>, you'll end up with a picture that is larger than your LCD can fit and you will have to crop it. If you take that same picture at 2 megapixels, you will have roughly the same quality picture except that it will now fit your screen, is smaller in file size, and thus takes up less storage on your flash card, and is therefore going to upload faster to Facebook, Flickr, Picassa, etc. If you want the target in your picture to be bigger, then use your optical zoom instead. If you mainly take pictures to share on the web or the network, put in a Powerpoint slide, or print on 4x6 paper, then an even lower resolution will be sufficient. Your home Blu-Ray player or High Def TV can output 1080p . This is still only about 2 megapixels.
The bottom line is cameras these days are marketed with higher megapixel ratings. But don't believe the marketing hype. Use moderate megapixel settings on your cameras when you know what the destination of those images will be. Smaller image files use storage more efficiently. Don't waste your storage or your money on more megapixels that do not benefit you. If you inherit pictures that are large in size and resolution, you can resize them to be a lower resolution and a smaller file size. Use Office Picture Manager or other photo editing software.
-Written by Andrew Song, BreaIT Specialist II.