Phone Camera Megapixels Explained: The REAL TRUTH

Ever since the camera became one of the biggest selling points on smartphones, a lot of emphases has been placed on the number of megapixels a phone packs in its camera. If you ask people what makes a phone camera great, the majority of them will probably say the number of megapixels it has.

To be fair, they wouldn’t be wrong. Megapixels are one of the things that differentiate a good smartphone camera from a bad one. So, it’s no wonder smartphone manufacturers put so much emphasis on them.

In fact, today we see some big-name smartphone brands revealing mobile cameras with megapixel counts upwards of 40, 60, and even 100!

But, does it really matter how many megapixels a phone camera has? And if so, how much is enough? Before we dive into that, you need to understand what megapixels are.

Megapixels

The term ‘megapixels’ can be confusing because some people use it to refer to the size of a digital image, while others use it when talking about the number of pixels on the camera’s image sensor. These two uses of the term are actually very closely related.

If you breakdown the word ‘megapixel’, the first part (mega-) is a prefix that means ‘one million’ or ‘of one million’. The second part (pixel) is a combination of two words-- picture and element. So, ‘megapixel’ means a million picture elements or pixels.

What are pixels?

On a digital image, a pixel is a very tiny dot or square that contains visual data. Pixels are the tiny building blocks that create an image. The total number of these building blocks is collectively known as megapixels (MP).

portion of picture magnified to show pixels

A magnified portion of picture that show tiny blocks of colour (pixels) that make up an image.

So, if a smartphone photo is said to be 12MP, it means it is made up of 12 million little dots or squares of different colours. In simple math, the dimensions of the image would be four million pixels wide by three million pixels high.

4 000(w) x 3 000(h) = 12 000 000

This is known as the resolution of an image. It determines detail. The more of these pixels you have, the finer and more detailed your image will be. Therefore, pictures from a camera with 20MP could look more detailed than those from a 12MP camera.

While it is correct to use ‘megapixels’ when referring to the resolution of a digital image, the correct term to use for the “pixels” on the sensor is ‘photosites’.

Image sensor photosites

A photosite is a light-sensitive area found on the surface of every digital camera’s sensor. When light enters the camera and strikes the sensor, it is the photosites that capture the light and generate data to create an image.

Closeup of the surface of a camera image sensor. The red, green, and blue spots are photosites/pixels with a colour filter array places over them.

That’s just putting it in really simple terms. If you want to know exactly how a smartphone camera captures and produces an image, then you should definitely read through this super-informative article.

Photosites are commonly called pixels because, depending on the design of the sensor, a single pixel on a digital photo tends to have a corresponding photosite on the sensor that provides the pixel’s visual data.

For this reason, when referring to the number of photosites on a sensor, manufacturers use the term megapixels because it reveals how many pixels are in an image created by that camera.

Photosite size

Arguably more important than the number of photosites, however, is their size. Pixels/photosites are measured in microns, which is an abbreviation of micrometres. The symbol for this is ‘µm’ or simply ‘µ’.

One micron is a millionth of a metre or about 0.00004 inches. For comparison, the size of a single human red blood cell is typically about 5µm across.

Typical size of a smartphone image sensor photosite

The size of the photosites on smartphone camera sensors differs from phone to phone and from sensor to sensor. And as mobile camera technology improves, so do the pixels, especially in high-end devices.

It’s not uncommon to find high-end smartphone sensors with pixels as large as 1.4µm or even 2.44µm. On the other end of the scale, you can find photosites as small as 0.8µm.

A lot of smartphones that have cameras with 64MP and more have 0.8µm pixels. When pixel binned at a 4:1 ratio, these merge and become a 1.6µm equivalent super-pixel.

The Samsung Galaxy S20 Ultra takes things even further. Its main camera has 108MP that are 0.8µm in size. When it pixel bins, it uses a 9:1 ratio (108MP becomes 12MP) which makes each super-pixel about 2.4µm big.

Impressive as that might be, it still pales in comparison to DSLR pixels which can be as big as 8.4µm and more.

Why does the size of the photosites matter?

As already mentioned, photosites are responsible for catching the light that enters the camera. And because photography relies solely on lighting, the more light photons the sensor can capture, the better the images the camera produces will be.

So, in order for a camera to produce quality photos, the sensor should have large pixels to catch as much light as possible. This is especially beneficial when taking photos in low light conditions.

Think of photosites as buckets that catch rainwater. The bigger the bucket, the more water you will get. And that’s what you want-- as much water as you can get.

Small photosites obviously don’t capture as much light as larger ones. As a result, images from image sensors with small photosites often don’t perform well when the lighting conditions are not ideal.

To brighten up the image, you can use a number of proven methods, one of which is to raise the brightness electronically by increasing the ISO.

But as is the case with all electronic equipment, noise can be an issue in mobile photography. When raising the brightness of an image electronically, you also raise the inherent noise floor.

Therefore, there’s a certain threshold up to which you can increase the ISO before the image quality of your photos is degraded by digital noise.

How far you can increase the brightness of an image by raising the ISO before noise is introduced varies from camera to camera.

However, sensors with small photosites are more likely to have problems with digital noise if the lighting conditions are not ideal.

The larger the photosites, the less you have to worry about digital noise.

What determines the size of a photosite?

The size of a photosite is ultimately at the discretion of the manufacturer. However, the size of the sensor itself is one of the biggest determining factors of the size of the photosites.

The physical size of an image sensor is fixed. The number of photosites that can fit on an image sensor can vary. The more photosites on a sensor, the smaller they become in order to occupy less space on the sensor and make room for more. The fewer the photosites on a sensor, the larger they can be.

A typical smartphone camera module and its sensor measured on a ruler. Source: gigazine.net

The reason why the pixel size of smartphone cameras is so small is that the sensor is small. Remember, unlike a dedicated camera, a smartphone has to serve other purposes other than photography.

Therefore, the image sensor can only be a certain size in order to make room for other smartphone components.

How do sensor photosites relate to image pixels?

As previously mentioned, a digital image pixel is created from the data captured by the corresponding photosite on the camera’s image sensor. A smartphone camera sensor with twenty million photosites will produce a 20MP picture.

However, things don’t always have to work that way. An example of this is pixel binning, where several pixels are merged to create one “super-pixel”. The aim of this is to reduce the noise problem common in sensors with small pixels.

This is a common practice found in smartphones with high megapixel cameras. They merge the light information gathered from four photosites to create one digital image pixel. That’s a pixel binning ratio of 4:1, which sees a 64MP sensor capture 16MP images albeit with larger pixels.

So, with all that said…

What are megapixels?

The term ‘megapixels’ refers to the number of tiny picture elements called pixels that make up a digital image. A million pixels are known as a megapixel. Therefore, a 12MP photo is made up of twelve million pixels.

Pixels may also refer to the photosites found on an image sensor, that capture light information to produce the image. It is very likely that a 12MP image would have been captured on a sensor with twelve million photosites or more.

Megapixels and picture quality

It’s a common belief amongst layman mobile photographers that more megapixels mean better picture quality. While there is some truth to that, the reality is they don’t. At least not entirely.

There are other specs of a smartphone camera that contribute to picture quality such as the sensor, pixel size, and the lenses. But they way digital photography devices were marketed in the past, consumers latched on to the idea that more megapixels meant better picture quality.

Perhaps in the smartphone camera sphere, consumers may have held a misguided belief that the higher the smartphone camera megapixel count is, the closer in quality the photos will be to those taken with a DSLR camera.

Before I learned more about cameras, particularly smartphone cameras, I would be disappointed every time my favourite phone company had fewer megapixels than their competitors. Back then, I believed megapixels were everything.

Don’t get me wrong. Megapixels still play an important part.

How the number megapixels affect the picture

Although they aren’t the alpha and omega of image quality, there’s no doubt that the number of megapixels on a smartphone camera greatly impacts the pictures that come out of a camera. This impact can be seen in picture quality and resolution.

A camera that has lots of megapixels will produce high-resolution images. The higher the resolution, the finer the detail of the images. High-resolution photos can be printed in large sizes without worrying about pixelation.

Pixelation is the result of taking an image and enlarging it beyond its maximum size. The image does not look smooth and its pixels are very obvious to spot from a distance.

The lower the megapixel count of an image, the smaller its physical size when printed or displayed at optimum quality. To print or display a large version of it will require you to enlarge the image which will undoubtedly cause pixelation.

On the other hand, you could get better picture quality from cameras with fewer megapixels, provided the pixels are big enough. Some of the determining factors of picture quality are sharpness, brightness, and minimal digital noise. Images made from sensors with large pixels often tick these boxes are more.

So, because bigger pixels capture more light, a camera with fewer megapixels may not produce a large photo but it will most likely perform better in low light conditions.

If you only need to print or display images on a smaller scale, for example when sharing on social media or using a small photo printer, then a phone camera with a modest megapixel count is more than perfect.

And speaking of small printers, in my opinion, the best portable printer is hands down the HP Sprocket Plus. This lightweight pocket-size printer produces crystal clear 3x2” photos directly from your smartphone via Bluetooth. You can even customize the shots in the app before you print them. It’s just brilliant. Check it out at Amazon.

How the sensor affects the megapixels

A big sensor generally means more resolution because you can fit more pixels onto it. Larger sensors also perform better in low lighting with less noise and high dynamic range.

Why? Because large sensors can fit larger pixels. Just like how a large bucket can catch more water in the rain, large pixels are able to capture more light. The more light photons the sensor’s sizeable pixels can capture, the better the camera performs in low lighting conditions.

Obviously, the bigger the size of the pixels, the more space they occupy on the sensor. So instead of 20 million tiny pixels on a 1/2.55” sensor, you’ll end up with 12 million larger pixels on a sensor of the same size.

In other words, if two smartphones with identical sensors were compared, the phone with a 12MP camera could have better light sensitivity and therefore brighter pictures with less noise than a camera with 20MP. However, the 20MP camera will have a larger more defined picture, albeit possibly somewhat noisier.

How many megapixels are enough?

So, how many megapixels are enough for a smartphone camera? This is similar to asking how many bricks are enough to build a house. It depends on the size of the house, the size of the bricks and the design of the house you’re building.

If you’re building a large house with super-fine architectural details, then you’d need a lot of smaller bricks than if you were building a small and simple house.

The same applies to the megapixels on smartphone cameras. It all depends on the size of the sensor (house), the size of the pixels (bricks) and what the manufacturer wants for the camera (design).

For example, if a smartphone company decides that they would like their device’s camera to focus more on light sensitivity than super high-resolution pictures, they would have larger pixels on their sensor. That means fewer pixels than on a camera with a higher resolution.

The number of megapixels that can be considered enough really depends on you and what you wish to do with your photos. If you’re going to keep the photos to yourself or print them and share them with friends and family, then you don’t need to worry about having a camera with lots of megapixels.

All you need is a phone with a good camera and a home photo printer that can give you the best prints. By far, the best printer in this department is the Epson SureColor P400, in my opinion.

Sure, it may be pricey but it’s worth what you get. However, there are some cheaper and pretty decent desktop photo printer options available.

If smartphone photography is nothing more than just an occasional pastime for you and you keep the pictures to yourself or only share them with a few friends and family, you might find that even a decent 8MP phone camera might be all you need.

If you’re going to sell your photos or make large prints and posters, then even a phone camera with 12 or 16 megapixels or more will work well for you.

But these days primary phone cameras generally have more megapixels than that. In my opinion, smartphones don’t need to have 40 or more megapixels.

In fact, some of the flagship smartphones from popular companies hardly go beyond 12 or 16 megapixels and yet they produce incredible photographs.

Why do some smartphone cameras have so many megapixels?

In the past, a reason some smartphone companies padded their cameras with a lot of megapixels was so that the digital zoom wouldn’t degrade the quality of the photo too much when the image was cropped and expanded to fit the frame.

Today, many high-end smartphone cameras have optical zoom and thanks to periscope cameras, some of them can reach up to 5x optical zoom. However, they still do rely on high megapixels for hybrid zoom and digital zoom.

But, to be honest, it’s all a marketing tactic. The idea of having tons of megapixels on their mobile camera is exciting for some people. It gives them something to brag about. Smartphone manufacturers use that to entice people into buying their product.

As proof of this, most mobile cameras with high megapixel counts pixel bin by default. They are set to take pictures at a lower resolution automatically because there is really no need for anybody to take such large-resolution photos with their phones.

Do all the cameras on a phone have the same number of MP?

One would assume that despite having different lenses, the cameras on a phone would at least have the same sensor. But that’s not the case. Not always.

The number of megapixels each camera has on a phone with multiple cameras depends on the manufacturer and the setup of the cameras on the phone. There are smartphones that have dual cameras, both of which are 12MP. The main difference is one camera has a wide-angle lens and the other a telephoto lens.

On other smartphones, there is a huge difference in megapixel count between the different rear cameras. In most cases, the primary rear camera has more megapixels than the secondary cameras.

Because they don’t capture and save photos like other cameras, specialised 3D cameras such as ToF cameras don’t have nearly as many megapixels as other cameras on a smartphone. Their resolution can be around 0.3MP.

If you don’t know what a ToF camera is, then you need to catch up with the times. Learn about ToF cameras here.

Smartphone cameras with monochrome sensors specifically dedicated to depth-sensing can be around 2MP on certain mobile phones.

Mobile camera MP vs. DSLR MP

An ordinary, dedicated camera with a 24MP resolution will produce better quality pictures than any smartphone of the same resolution. Why? Mainly because of the much bigger sensor.

A typical full-frame DSLR sensor is 36mm x 24mm in size, whereas an average smartphone sensor only measures more or less 5.5mm x 4mm depending on the manufacturer. That means a full-frame DSLR camera sensor has an area that is about 40 times bigger than that of a smartphone sensor.

If we look at the 24MP comparison between a digital camera and a smartphone camera, this means that both sensors have 24 000 000 pixels despite the size difference. The obvious deduction from this is that the larger sensor will have larger pixels to fill its surface area.

The smaller sensor, on the other hand, has to cram the same amount of pixels onto a very small area, which means the pixels themselves will have to be super tiny.

rough comparison between dslr and mobile camera sensor

Rough size comparison between pixels on a DSLR sensor and pixels on a mobile camera sensor due to sensor size.

As previously mentioned, larger pixels capture more light and are less susceptible to displaying high noise levels and can, therefore, produce better results than small pixels.

Do megapixels really matter then?

Yes, the number of megapixels your smartphone has does matter because it dictates how detailed the pictures from it will be.

However, megapixels are not the only thing that matters as many consumers have been led to believe. Things like sensor size and pixel size have to be considered in a balancing act with megapixels.

Is there anything wrong with wanting a phone with a camera that has a lot of megapixels? Of course not! If you want to buy a phone with a camera that packs an impressive amount of megapixels on its sensor, then be sure to check out these phones with the highest megapixel cameras (to date).

A benefit about that is that a phone camera with many megapixels can take high-resolution photos, which means you can create large prints from them. That’s a potential opportunity to make money with your smartphone photos.

If you have photos that you are really proud of and want to turn them into works of art for your home or to give as a gift, I recommend you check out Pictorem. They can print your photos on canvas, metal, wood, acrylic, and more.

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If your photos aren’t yet at the point where you’d want to have them printed and displayed, don’t worry, you can get there, too. All you need to do is learn and practice.

That’s why I’ve put together a simple introductory guide that will help you take beautiful mobile photos that could be good enough for you to print and display in your home or share with family.

If you want to learn about how to improve your smartphone photography, download the 5 Ways To Improve Your Smartphone Photography ebook by clicking on the banner above or by clicking here. There’s a lot to learn in its 22 pages of content and it’s ABSOLUTELY FREE!!!

Otherwise, for some quick tips on how to capture great photos with your phone, check out these 15 Tips on How To Take Amazing Photos With Your Phone.