Modern smartphones come with powerful camera systems, and there's a lot that goes behind the scenes to make your photos look beautiful. One such thing is pixel binning.

You must've seen how Samsung uses terms like "nona-binning" or "Adaptive Pixel" in its marketing when referring to pixel binning, claiming that it improves low-light performance. But does it, really? Let's learn what pixel binning is, why it's used, and how it works.

Why Smartphone Cameras Use Pixel Binning

Before learning what pixel binning is and how it works, you should first know why it exists. See, smartphones face a big problem when it comes to cameras: size limitation. A camera sensor is basically a plate of millions of pixels that capture ambient light. So, the more pixels there are, the more light they can capture to produce a better image.

When we say "pixel" in this context, we don't mean the pixels on the display that emit light, but instead the photosites on the camera sensor that capture light. This light is then converted and used to produce the image you see on your screen.

Now, here's the problem: if we keep adding more pixels, we'd also have to keep making the sensor bigger to fit them in. This is difficult because the camera module on a phone is just one part of its body; you also need to fit the battery, motherboard, speaker, and the plethora of sensors found in a smartphone.

Samsung Galaxy S22 Ultra camera and iPhone 13 Pro Max camera side-by-side
Image Credit: SuperSaf/YouTube

To overcome this limitation, tech companies came up with a clever workaround. Instead of making the sensor absurdly big, they shrank the pixels themselves, fitting more pixels in a given space to increase the maximum theoretical image resolution.

For reference, the 12MP sensor on the iPhone 13 has a pixel size of 1.9 µm (micrometer), but the same is 1.22 µm on the iPhone 14 Pro's 48MP sensor. And the 108MP sensor on the Galaxy S22 Ultra has pixels just 0.8 µm in size—one of the smallest that we've seen.

What Is Pixel Binning? How Does It Work?

Pixel binning is an image processing technique where four or more neighboring pixels in a camera sensor are combined to form a superpixel (or "tetrapixel" or "nonapixel" as Samsung calls it) which carries the sum or average value of all the pixels in it.

Note that the pixels don't physically move or morph into each other on a hardware level; it's just their photonic data that's combined via software to imitate a larger pixel.

Let's understand this with an example using the iPhone 14 Pro Max and Galaxy S22 Ultra. The iPhone 14 Pro Max does 4-in-1 pixel binning (2x2 array) to bring down the resolution of the image from the native 48MP to 12MP. Similarly, the S22 Ultra does 9-in-1 pixel binning (3x3 array) and brings down the resolution from 108MP to 12MP.

Samsung nona-binning on 108MP sensor
Image Credit: Samsung

Lowering the resolution like this allows your phone to process photos faster, so you can view a shot right after clicking it. In contrast, shooting at full resolution adds excessive workload and takes much longer to process.

Also, remember that megapixels and megabytes are not the same things. Megapixels refer to the number of pixels present on the sensor (a fixed unit), and megabytes refer to the size of the image file (a variable unit), which depends on how much info there is in your shot.

For example, the Galaxy A53 has a 64MP camera and does 4-in-1 pixel binning to give 16MP shots. By default, it takes 4624 x 3468 resolution shots for a total of 16,036,032 pixels or simply 16MP (one megapixel is one million pixels). If you switch to the full-res mode, you get 9248 x 6936 resolution shots for a total of 64,144,128 pixels or 64MP.

Pixel Binning Does Not Guarantee Better Photos

Here's something that might be hard to swallow: pixel binning is a solution to a fake problem. The whole idea behind pixel binning is that it allows putting more but smaller pixels instead of fewer but larger pixels on a camera sensor. This is unnecessary because a larger individual pixel will always capture more raw light.

In comparison, a superpixel of the same size carrying the photonic data of multiple smaller pixels has to guess what the final shot should look like—and it doesn't always do a great job. This is why photos from Samsung phones look over-processed sometimes while the ones from iPhones look more natural and consistent.

photo of a person taking pictures on their smartphone

Tech companies love bragging about how many megapixels their new camera sensor has, and because of this, the average smartphone user has come to believe that a higher megapixel count means better image quality. It doesn't. Image quality is determined more by the size of the sensor itself, not the number of pixels on it.

The number of megapixels determines the maximum image resolution that your phone is capable of shooting in. The only practical benefit of this is that you can zoom and crop into your photos without them becoming blurry. Megapixel count tells you nothing about color science, white balance, dynamic range, or anything as such.

The supposed benefits of pixel binning are the result of not the technique itself, but the powerful image processing algorithms and the chipset in your phone. It's the latter that does the hard work of making your shots look brighter, less grainy, and more vibrant.

The reason why a pixel-binned lower resolution photo can sometimes look better than a full resolution photo is that applying image algorithms is harder on a larger photo as that uses more processing power. A smaller photo can be processed immediately.

Pixel Binning Is a Workaround, Not a Feature

The purpose of pixel binning, ultimately, is to allow raising the maximum theoretical image resolution a smartphone camera can take, all while lowering it enough that your phone can process your photos quickly for everyday use.

Image resolution matters because you obviously want to zoom into your photos without losing detail, but numbers like 108MP are frankly unnecessary.

The best way to ensure that the phone you're looking to buy has a good camera system is to simply check camera samples and watch reviews. Don't obsess over the technicalities too much; if you like what you see, that's the right camera for you.