Understanding Camera Resolution

Cameras are being embedded everywhere. We find them on our phones, tablets, laptops and other types of gadgets as well. Digital cameras are getting sharper and smarter by the day. Some cameras capture good quality pictures while some cameras don’t. We frequently come across the camera specs which mention the ‘MP’ value of the camera. You understand the fact that a 12MP camera takes better pictures than a 5MP camera. Have you ever stopped to think what makes it better? More pixels means better pictures. Why exactly is that?  

It’s like telling a story

Let’s consider the following situation. Peter just came back from a wonderful trip. The place he went to was very exotic and he wants to describe it to George. Now, George is in a hurry and so he asks Peter to describe the whole trip in just 10 words. That’s very less right! Peter will hardly be able to convey what happened. Peter thinks hard and comes up with an apt 10-word description. It’s not much, but it gives George a rough idea of what it was like. George runs into Peter later that evening and now that he has some time. He asks Peter to describe the whole trip in 50 words. Peter feels a bit comfortable and describes the trip in greater detail. George will now get a better idea of what it was actually like. It’s still not enough, but it’s better than just 10 words. George meets Peter again the next day and now they are both free. George wants to know all about the wonderful trip and the exotic place. Peter describes the whole trip in 500 words and he gives out complete details of the trip. Although it took more time, the transfer of information was maximum.

You see where I was going with the above analogy? Pixels are like words. The more pixels you have, the better you can describe the actual scene. You can never actually describe it exactly the way it was, but you make the difference negligible to the human eye.

What happens under the hood of the camera?

A digital camera is a device used to create digital images from an actual physical scene. Now what exactly is digital here? When you capture an image using your camera, the light-sensitive sensors on the camera capture the brightness and color information. These sensors are called pixels. How do they do it? Well that will take a full blog post to explain because we will have to go deep into optics and properties of materials. Now each pixel will be represented by some bits so that we can store them. This is where the digital part comes in. It’s like rounding off. Just like how we discard small change when we deal with money, computers also discard some minor things to digitize the data and store it.

I keep hearing this thing called ‘camera resolution’. What is that?

Imagine a rectangular surface. You are asked to divide the surface into smaller rectangles. These smaller rectangles correspond to pixels. Each rectangle can record only one measurement. This means that if the size of these rectangles is big, the image will not be sharp. It’s just like how using less words hampered Peter earlier. Bigger rectangles would mean less number of total rectangles on that original rectangular surface. Now if you chop up that rectangular surface into very small pieces, you will have a lot of rectangles. It’s like giving Peter the freedom to use more words. The captured image would be sharper in this scenario. The number of pixels gives us an idea of ‘camera resolution’. Higher the number of pixels, higher the resolution.

If that is the case, then why don’t they all manufacture high resolution cameras?

Dividing up the rectangular surface consumes time and energy. If you split the surface into small number of rectangles, it saves time and energy but the image quality is bad. If you split the surface into large number of rectangles, it takes more time and energy but the captured image would be better. This is the trade-off the camera companies are dealing with! This is the reason why cameras with less number of pixels are usually cheaper than cameras with higher number of pixels.

Modern cameras are very advanced and a lot of processing goes on under the hood. The processing includes image stabilization, intensity adjustment, histogram equalization, high dynamic range imaging and much more. People are actually bad at taking pictures, it’s because of these technologies that the image almost always comes out to be good.


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