Do we really need HIGH MEGAPIXEL sensors in mobiles and cameras?

    In today’s market, it looks like ‘HIGH MEGAPIXEL CAMERA’ is the new normal. Because in every camera and mobile advertisements, it is highlighted in big and bright fonts that those gadgets have higher megapixel counts. All the companies are in a race of providing higher resolution photos to the customers. 21 mp, 48mp, 64mp, even up to 108 mp, largest of known mobile phone resolution at this time, July 2020. 

    But do we actually need these many pixels? What are advantages of having higher megapixel sensor? How it affects image quality and usability of a photo? All these questions will be answered in this post. So, stay tuned. 

    Most people don’t know actual meaning of the word ‘Megapixel’ and they get fooled by the marketing gimmick of mobile companies. This word is made up of two words, MEGA and PIXEL.  Word ‘MEGA’ means ‘a count of 10 lac or 1 Million’ and PIXEL means ‘photon collecting small individual units of sensor’. These individual pixels convert incoming photons into electronic information. On sensor, pixels are arranged in thousands one in front of another in a row and thousands of such rows, one below another, forming a grid of millions of pixels. 

In short, 1 megapixel sensor has 10 lacs or 1 million pixels in it, arranged in a grid of rows and columns. The count of pixels in a row and column defines the resolution of that sensor. For e.g., if a sensor has 4000 pixels in each row and 3000 pixels in each column, then that sensor has a resolution of 12 megapixels, where total pixels count is 12,000,000 (4000 x 3000 = 12,000,000). 

This pixel count of a particular sensor is decided by the maker company, based on proposed use of that camera. This means, if there are two sensors of same physical dimensions, one of them might have a resolution of 12 megapixels and another might have the resolution of 30 megapixels. To understand this concept, let us see an example.

Suppose we have a sensor of 10 mm horizontal dimension. So the company will decide whether to put ‘1 mm wide 10 pixels’ in a row or ‘0.5 mm wide 20 pixels’ in a row. So less number of pixels will result in larger individual pixel size and more number of pixels will result in smaller individual pixel size. Because in both cases, sensor size is same. You can understand this by seeing following image. 

 

Just remember this information, because we will need it in next part of this post. 

    Now the question is, how many pixels do we need to get a good photo? This certainly has no particular answer. Because photo quality and number of pixels are not at all related to each other. Only the ‘size of individual pixel’ affects the quality of photo.

Confused? Hold, we shall see this in a bit detail now. Good photo can be divided into two parts. ‘Quality of the photo’ and ‘Details in that photo’. To get good quality of photo, we must have bigger individual pixel size (less number of pixels) and to get most possible details in the photo, we must have more number of pixels (smaller individual pixel size). 

    So in the previous example of 10 mm wide sensor, if we have 1 mm wide 10 pixels in a row, then the quality of photo will be higher, i.e., photo will be better in terms of brightness, contrast, sharpness, dynamic range, etc. 

But if we want to capture more details in our photos, then we will definitely need more megapixels. Because every pixel stores the information, which contributes to details of that photograph. So, more megapixels will allow us to capture more details. In same above example, if there are 20 pixels of 0.5 mm width, more information will be stored. 

I should clearly mention here that, quantity of details may be more, but quality of details will not be good, because of smaller individual pixel size. In this case, the quality depends upon the situation in which the photograph is taken. 

In short, smaller megapixel count gives ‘less details but with superior quality' and larger megapixel count gives ‘more details but with inferior quality’, off course, when the sensor size is same.

    Now let us see how all this information relates to mobile. We have seen the size wise comparison of mobile camera sensor and professional camera sensor. (If you haven’t read that post, click here:- Camera Sensor information You Need To Know)

So as mobile camera sensor is small, individual pixel size is very small. Thus, mobile camera quality is inferior to that of a camera. Also that small sensor is packed with more megapixels than the professional camera, resulting in further reduction of pixel size and as a result of that, reducing the  overall quality of photo. 

We can directly relate megapixel count to the amount up to which we can stretch the photo, without reducing it's quality. So the higher megapixel count helps us in zooming the photo more than photo having smaller megapixel count. To realize this concept just know that, if we can enlarge the less MP photo three times, then we can enlarge the large MP photo five times or more. 

In these expensive mobile phones, lenses are made up of good quality material, than those in other mobile phones. Also their sensors are more advanced and powerful than others. So, the problems occurring due to smaller pixel size get reduced and we get good quality photo. For example, noise occurred in the photo while capturing, gets removed in processing, up to a certain extent. 

So all in all, who needs higher megapixel count? Or when it’s good to have it? The answer is; it is for them, who want more details in their photos. Also when you have a higher resolution photo, you can crop it afterwards to get desired composition and still you get more MP than you actually need. For example, if we take a photo of a bird which is at certain distance from us, on a 20 MP sensor, then if we crop it down, the resolution will also reduce. But if we take same photo with a 50 MP sensor and then crop it down to even the half of it’s original size, then also we will have 25 MP photo at the end. 

So every company is in a race of providing higher megapixels in their phones or cameras. But the important thing to be remembered is ‘Not only pixel count, but sensor size and individual pixel size is also important, for taking a good quality photo’. 

And at the end, all this hustle is for those people, who need and crave for higher quality photos, like professional photographers or serious hobbyist photographers. Because in these cases, you are likely to get paid for your photos and more number of people are going to see it. 

Otherwise, some people only look for the story in the photo, regardless of it’s quality. And that is enough in some cases. Because any photo is good, only if it is liked by both photographer and the viewer. Isn’t it?

- Prasanna Joshi

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