How Big a Difference the Number of Megapixels Make in a Digital Camera
Every digital image consists of Pixels, the short for Picture Element . Millions of pixels combine to create a seemingly continuous and detailed image. Each pixel contains a series of numbers which describes its color and intensity. The precision to which a pixel can specify color is called its bit or color depth. The more pixels your image contains, the more quality and details of the image is described.
A megapixel is simply a unit of a million pixels. If a certain resolution of PPI (Pixels per inch) is required, then there is a maximum print size one can achieve for a given number of megapixels.
Why is it considered that the higher the number of megapixels in a digital camera the better is the image quality? A larger pixel has more light-gathering area, which means the light signal is stronger over a given interval of time. This results in an increased Signal to Noise (SNR) ratio which creates a smoother and more detailed image. The dynamic range of the images also increases with larger pixels. This is because each pixel well can contain more photons before it fills up and becomes completely white. The dynamic range is the range of light to dark which the camera can capture without becoming either black or clipping highlights.
A table of comparison of megapixels and the maximum print size available at different PPI
# of Megapixels |
Max Print Size at 300 PPI |
Max Print Size at 200 PPI |
2 |
5.8” x 3.8” |
8.7” x 5.8” |
3 |
7.1” x 4.7” |
10.6” x 7.1” |
4 |
8.2” x 5.4” |
12.2” x 8.2” |
6 |
10.0” x 6.7” |
15.0” x 10.0” |
8 |
11.5” x 7.7” |
17.3” x 11.5” |
12 |
14.1” x 9.4” |
21.2” x 14.1” |
16 |
16.3” x 10.9” |
24.5” x 16.3” |
If one takes a look at the above megapixel comparison table, one can see that a 2 megapixel cannot make a standard 4x6 inch print at 300 PPI, while it requires 16 megapixels to print a 16x10 inch picture.
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