A few days ago, Realme launched the Realme XT, the first smartphone in India to come with a 64-megapixel camera. The launch marked the latest move in what seems to be a full blown megapixel war in phone cameras, with 48MP having become almost a standard even in mid-segment smartphones.
In fact, even as this is being written, Xiaomi is believed to be working on a 100MP camera for one of its forthcoming phones. These huge megapixel numbers are a far cry from the relatively 12MP or 16MP sensors that were seen in most phone cameras at the beginning of the year.
So, does this mean that the cameras in this new crop of phones are at a whole new level? And if that’s the case, then why is it that some of the phones that reviews say have the best cameras—such as the iPhones, the Samsung Galaxy Note 10+, or the Google Pixel 3—actually use 12MP cameras.
All of which might make some wonder why then there is so much talk about megapixel counts? And just how much they really matter?
A measure of image size, rather than quality
Basics first: what is a megapixel? All pictures on a digital screen are made up of tiny dots called pixels. All these tiny dots put together make an image. Well, a megapixel is a million pixels.
When you read that a camera has a certain number of megapixels in it, it basically means it can take pictures that that many million pixels in them (the measure of the size of a picture is the number of horizontal pixels multiplied by vertical pixels—1024x768 and so on).
The more the pixels, the bigger the image. And of course, the bigger the image, the more you can see (in most cases). A 64MP camera would take an image of 9216x6912 resolution for instance, which is much bigger than the 4032x3024 image that a 12MP camera would take.
So common sense would suggest that more megapixels should be good, right? You get bigger pictures and logically, more detail.
Well, not quite. The truth is that a megapixel is more a measure of size, not of quality. The only thing more megapixels can truly guarantee you is the ability to get a much larger picture. So yes, if you are looking to print billboard-sized images, then perhaps a higher megapixel count will make a difference.
But just how good a picture will be in terms of quality (colour, depth, detail, contrast, dynamic range and so much more) depends on the quality of the camera’s other parts—the sensor that is fitted inside the camera, the lenses, the size of the aperture, the software processing and so on.
The megapixel-sensor equation
Sometimes, having more megapixels on a camera can actually even adversely affect picture quality. This is because the size of the sensor—the part of the camera on which light falls and the image is formed—is generally very small in a phone camera, often less than half the size of what you would get on a DSLR.
Now, when a large number of megapixels is squeezed into that tiny area, the size of each pixel gets smaller, and that affects its ability to collect light. And that in turn can affect image quality. This leads to noise (grains) in many pictures.
Sony’s six-year-old Cyber-shot RX100 has a bigger sensor than the new mega-megapixel smartphones, but it "only" has a 20MP resolution.
A number of brands like Xiaomi and Redmi have also tried to highlight that their phones feature not just more megapixels but also larger sensors. However, even then, most phone camera sensors remain much smaller even than the ones you get on DSLRs or even point-and-shoot cameras.
For instance, Xiaomi and Realme claim to have half inch or slightly more than half-inch sized sensors on their 48MP and 64MP camera toting phones, but Sony’s six year old Cyber-shot RX100 has a one inch sensor, at a 20MP resolution.
There’s more to cameras than megapixels
This does not mean megapixels are irrelevant. As we pointed out earlier, they are an important part of the photographic equation. In fact, if you are comparing two cameras with exactly the same set up (the same sensor, lenses, settings, aperture, etc.), then the megapixel count can make a crucial difference. A 48MP camera can capture much more detail as compared to a 12MP one.
The difference might not hit you on a smartphone display or a tablet, but take the same snap to a bigger display (like a large desktop monitor or television), and those megapixels will start making a difference. Anyone who has worked with a designer will have heard the demand for higher resolution, “print quality” images—well, it is megapixels that make that resolution higher. Which is why even some DSLRs come with high megapixel counts.
Another benefit of having a higher count of megapixels is digital zooming, especially in phone cameras. Unlike optical zooming, where the lens in the camera actually moves closer to the subject, digital zooming is basically cropping an image to make the subject appear larger.
Of course, when you cut out bits of an image, you remove megapixels from it, which affects its quality and the amount of detail it contains. So if you have a very high resolution image, you can afford to remove some part of it, without losing too much quality. A number of phone brands combine this with software to get what they call “lossless zoom”, allowing users to zoom to an extent without the usual loss of quality.
So do megapixels matter? Yes, they definitely do. But they are definitely not the main reason why a camera is good or bad. There are a number of factors that make a camera great, and megapixel count is just one of them, so before you look at the megapixel count of a camera, just be sure you have checked out other factors as well.