Megapixel is a term used a lot by everyone now a day, but before we go into Megapixel, let’s understand Pixel first. Pixel is a word derived from Picture Elements. A pixel is a unit of programmable colors on a picture. These are small dots (typically in square shape) what makes the image. A picture is divided up into a matrix of thousands or even millions of pixels. Typically, we cannot see the individual pixels, because they are so small. They are arranged in two dimensional grids.
A megapixel is equals to one million pixels e.g. 5megapixel camera will have 5,000,000 pixels. The higher the megapixel number, the larger the image size captured by the camera. Therefore, if you are looking at a larger image size, look for a higher megapixel camera.
How is the megapixel calculated?
Let’s take the example of Nikon D810 a full frame DSLR. The maximum resolution image quality specified is 7360X4912 pixels equal to 36,152,320 (7360X4912) pixels and it comes out to be 36.15 megapixel.
Let’s take one more example, Nikon Coolpix A900 which has a sensor size 1/2.3-in. The maximum resolution image quality specified is 5184X3888 pixels. Which means 20,155,392 (5184X3888) pixels. Which means 20.15 megapixel.
The pixel count of a DSLR with a full frame sensor with a 20-megapixel image quality and a compact camera with 1/2.3-in sensor with same megapixel is same. However, there is a huge difference in the picture quality because of the size of each pixel. The bigger the pixel size, better the detailing in the image. The numbers in the pixel count is always misleading. A general perception is, having more megapixel in a camera will give better the picture quality which is not necessarily true.
Out of the many factors which contributes to the quality of the image produced by a particular camera, size of the pixel is often least considered. Pixel converts light into data. The data recorded through a pixel is made out of both good and bad quality information. Bad quality information is often called as noise or grain, which also results in low color saturation, contrast etc. All pixel records same amount of good and bad quality information. Larger pixel records more good quality information therefore it produces better quality images. So,it’s very essential to understand that size of the sensor has a major role in the quality of the image.