What are megapixels in a phone camera (and why they’re not the most important thing)

A few weeks ago, we tested Samsung’s latest model: the Galaxy S23 Ultra. A superb high-end phone that, despite being released in January, could still be one of the best smartphones of the year in December.

Among all its attributes, there is one that stands out more than all: the 200 megapixel sensor that brings its main camera. A huge number, which almost doubles that of its previous version — the S22 Ultra — and which more than quadruples the 48 MP of the iPhone 14 Pro Max, Apple’s flagship.

Instinct almost always leads us to believe that more is better and more megapixels makes for a better camera. And even if in the case of the Galaxy S23 Ultra it’s a bit like that —its camera is really good—in reality the deputies have little to do with this equation.

In addition: the number of megapixels itself has almost no influence on the quality of the photos.

A megapixel corresponds to a million pixels. Rather, thousand pixels by thousand pixels. Next question?

On the right, the pixels. They are the smallest unit of size in digital images, a very, very small square of a single color which, together with millions of other squares, forms everything we see on any of our screens: photos , texts, applications, videos. All.

A 1280×800 laptop screen, for example, has 1,024,000 pixels. In other words, if we do the calculations correctly, it amounts to just over one megapixel. This means that a 1MP image, opened at full size, can be viewed in its entirety on a monitor of that resolution. It should therefore be used as a wallpaper.

And a photo of 1920 pixels wide and 1080 pixels high, a so-called Full HD resolution, would be just over 2 megapixels.

Not necessarily. The megapixels, as we explained, inform about the resolution of this image. The more MP, the more resolution; the higher the resolution, the larger the size. While an image with a lot of MP will contain more information – ideal if you want to print it or use it for design work – on a screen it won’t look much different than an image with less.

As for photography, it’s the same: a 50 MP selfie will only be bigger than a 12 MP one, not better. And unless you want to have a attach yourself in your room, there will be no major difference between one resolution and another. For this reason, until recently, iPhone cameras remained at 12 MP, and despite this, they take better photos than other – less expensive – models that exceed 100 MP.

No: megapixels are what they are. And in the case of cell phone cameras, they indicate the size of the image that the photo sensors can capture. Even a higher number of megapixels can be detrimental in certain cases: the more megapixels there are in the same space, the smaller they will be and the less light they will be able to capture. And in photography, less light means less information, more noise and poorer image quality.

So if we want quality i.e. true and vivid colors, deep blacks, sharp textures, we have to look at other features.

Several aspects affect the final quality of a photograph. First of all, there is your talent: machines make photos, not miracles.

Well, let’s say you have a photographic eye. If you want to improve it, you need to look at at least three features of the mobile phone:

• your goal
• The size of your sensor
• Your photography software

In the first case, that of lenses, the information used to assess their quality is their aperture: how much the shutter is able to open to receive the light and take the photo. The more you get, the more information you can capture in unfavorable conditions, such as night or backlight, in addition to having more focus range.

The maximum opening of a diaphragm is expressed by a letter F: The lower the factor, the more it is able to open. Why is it inversely proportional? Because if the value is 1, it means it can be fully opened. If, on the contrary, it is 8, it means that only an eighth of the room will open, receiving less light.

So a lens that has an aperture of f/1.5 will be much more flexible and versatile than a lens with f/4.9.

The sensors are the digital version of old rolls of photographic film. There, the light information that we captured by pressing the red button remains frozen, to then be converted into a digital file.

As explained on the site American Scientist , “The size of the image sensor is important and, in general, the larger the sensor, the larger its pixels. And the larger the pixels, the more light they can collect. »

In other words, the 12 MP of a camera with a large sensor will capture a higher image quality than the 100 MP of a mobile with a small sensor. In this case, size matters.

Unfortunately, we do not always have this information from the manufacturers. We know, for example, that the sensor of the iPhone 14 Pro has pixels — or photoreceptors — of 1.22 micrometers (µm), while those of the Sony Xperia Pro-I — which has the most powerful camera on the market — measure twice: 2.4 µm. The one with the fabulous Galaxy S23 Ultra? Only 0.6μm.

The work of a camera does not stop when it receives the information in its sensor. On the contrary: there, it is only just beginning. Then there are many algorithms and software which improve the image, enhance the colors, stabilize the lines and optimize many factors.

Manufacturers who have succeeded in fine-tuning their software The cameras are Apple — which is why it only needs 48 MP —, Huawei and Samsung, which is why they cost what they cost. Now mid-range brands, such as Xiaomi and Oppo, are also bringing their own.

Sometimes, yes, these programs go too far, delivering unnatural photos, with very synthetic contrasts or unreal colors. There they try to compensate for certain defects – such as the small size of the sensor or the little light that the lens lets through – with the use of certain tools, such as HDR.

Who do you take me for that you ask me so many questions? ChatGPT? The problem was the megapixels, not all the elements involved in the result of a digital photograph. But I’ll try to explain it briefly: HDR stands for high dynamic range, a tool that maximizes a camera’s ability to capture highlights and shadows in a photo.

They achieve this by taking multiple photos of the same moment but with different exposures – some darker, some brighter – then automatically combining them, extracting as much information as possible and leaving a more balanced image. Understood?