Megapixels

You would have heard a lot of people talking about mega pixels whenever it comes to camera. Whenever it comes to comparing cameras, the first question that someone asks me is "How many mega pixels does that camera have?". In fact I think that is one of the most uneducated question that someone can ask about cameras. Putting it simply, mega pixels don't make a camera. Now lets see what exactly it is.

First let us see what is a pixel.
Pixel stands for Picture Element (pics = pix). A pixel is like a single dot in the image. The image is composed of lots and lots of pixels. Each pixel is of a specific color. Assume that an image has pixels of a single color - red, the entire image will be red in colour. This way in a photo, there are multiple pixels each with a different color and hence a nice colorful image is formed.

A picture is measured in terms of its resolution. The resolution gives the number of pixels horizontally and vertically. So a picture of resuolution 640x480 has 640 pixels horizontally and 480 pixels vertically. Now let us see how many pixels are there totally in the image.

Total pixels-> 640 x 480 = 307200 pixels.

Consider an image of size 1280x1024..
Total pixels -> 1280 x 1024 = 1310720 pixels.

Lets write this in tens, thousands and millions.
1310720 => 1,310,6720 pixels. This is almost equal to 1.3 million pixels.
So, a camera capable of taking images at 1.3 megapixels can take images of resolution 1280 x 1024. Similarly a 5MP camera can take images of resolution 2592 x 1944. This is the basis of megapixels.

Also, in many cameras you will find something called Total Megapixels and Effective Megapixels. The total megapixels is the number of pixel sensing elements in the sensor of the camera whereas the effective megapixels will translate into the size of the image. The reason for this difference lies in the way the sensor is built. In conventional sensors, there are a fixed number of sensors for measuring red, green and blue and this is then processed into the resultant image. As a rule of thumb, if you see 2 different megapixel ratings for a camera, the one that you are concerned about is the smaller number. We will get into details of sensor construction later.