For many people, the camera is now the most important feature when choosing a new smartphone. Whether you’re using your phone to capture self-portraits or to record memories when on a family holiday, the quality of photos is a top consideration when choosing a new cameraphone.
When buying a cameraphone, many people like to compare the camera based on the number of megapixels. Today’s smartphones now offer anything from 0.3 megapixels up to 41 megapixels. In day-to-day life, how many megapixels do you actually need (e.g. for posting on social media and for printing your photos)? Can it sometimes be better to choose a cameraphone offering fewer pixels? Are there other things to consider besides the megapixel count? This article aims to answer these questions.
What Is A Megapixel?
Every digital photo is formed from pixels (or picture elements to give them their full name). In order to build a digital photograph, we start with a grid (12x8 pixels in the example image below). For each pixel, your cameraphone records the colour observed (each colour is recorded as a combination of red, green and blue). By taking the pixels together, we’re able to form our complete digital image.
Our sample photo consists of a grid of 12x8 pixels. Each pixel is given its own colour (formed through a combination of red, green and blue).
In general, an image with more pixels will have better quality. Take the following example. Going left to right, we quadruple the number of pixels at each successive stage. As the pixel count increases, the image progressively becomes clearer and clearer.
In general, the quality of an image gets better as the number of pixels increases.
With digital photos, we often measure the total number of pixels in an image. To give an example, your entry-level cameraphone has a VGA camera (640x480 pixels). The total number of pixels in each image recorded is 640x480 = 307,200 pixels. To save time, we often write this as 0.3 megapixels where one million pixels is equivalent to a megapixel.
Nowadays, a mid-range cameraphone will normally have a 5 megapixel camera. A high-end cameraphone normally has at least 8 megapixels (and as many as 41 megapixels on the Lumia 1020). For comparison, HD video (720p) is equivalent to 0.9 megapixels. Full HD (1080p) is equivalent to 2.1 megapixels.
How Many Megapixels Do You Actually Need?
With the ongoing trend of newer cameraphones having more and more megapixels, it’s worth stopping to ask how many megapixels you actually need for an image. Too few megapixels and you’re left with a blurry image that’s lacking in detail. Too many megapixels and you’re wasting storage on your phone (the extra pixels all use up extra space).
For Sharing On Social Media
For sharing on social media, it’s rather surprising how few megapixels are required. On many social networks, you’re only able to share your images at a resolution of up to 0.7 megapixels. Recording your photos at a higher resolution is unlikely to make a difference for sharing on social media.
- Facebook (0.5 megapixels). On Facebook, the standard resolution for photos shared online is 960 pixels in the longest direction. For a widescreen photo taken on a cameraphone (16:9 ratio), this corresponds to 960x540 pixels (equivalent to 0.5 megapixels). With the “high quality upload” option enabled on your phone, you can upload images of up to 2.3 megapixels (viewable through the “View Full Size” option).
- Instagram (0.7 megapixels). On the Instagram social network, photos are shared at a resolution of 640x640 pixels. As it’s a square photo (cropped from the rectangular original), your original image would need to be at least 0.7 megapixels.
- WhatsApp (0.5 megapixels). On WhatsApp, images are shared at 800x600 pixels. This is equivalent to 0.5 megapixels.
For Printing
If you often print your photos, it’s a good idea to capture your images at a higher resolution. Most professional photos are printed at 300dpi (300 dots per inch or 300 pixels in the space of one inch).
The following table shows the number of pixels required for high-quality print:
|
Print Size |
Number of Pixels Required |
|
Wallet-Size Photo |
0.5 megapixels |
|
Standard Photo |
2.1 megapixels |
|
A4 Borderless 8.27 x 11.69 inches |
8.7 megapixels |
|
A3 Borderless 16.5 x 11.7 inches |
17.4 megapixels |
For many people who will only print their photos at the standard size, 2.1 megapixels should already be enough. For a borderless A4 print, you’ll need a photo at 8.7 megapixels. It’s probably overkill to capture your images at an even higher resolution (photos are seldom printed larger than A4).
More Than 8 Megapixels?
As discussed, 8.7 megapixels is already enough for a borderless A4 print. Many people can get by with much fewer pixels: you only need 2.1 megapixels for a standard printed photo and 0.7 megapixels for sharing on social media.
With this in mind, some manufacturers have stopped engaging in the war for more and more megapixels. HTC’s latest flagship device, the HTC One M8, only features a 4 megapixel camera. Rather than adding more pixels to the camera, they’ve instead opted for larger-size pixels (larger-size pixels can collect more light hence giving more accurate colours and lower levels of noise). HTC call this development their “UltraPixel” camera.
Meanwhile, other manufacturers are still opting for a larger number of pixels. Samsung’s Galaxy S5 has a 16 megapixel camera, Sony’s Xperia Z2 has a 20.7 megapixel camera and Nokia’s Lumia 1020 has a mammoth sensor with 41 megapixels. It sounds a little overkill: indeed, a typical photo takes up 5MB of space on the Galaxy S5. Your storage will run out a lot faster and the extra pixels may make little difference. There is however an important benefit in that you crop images and print them at full quality.
Crop Without Losing Quality
The lack of optical zoom is a major disadvantage when taking photos on your smartphone. With dedicated cameras, you can normally use the optical zoom feature to enlarge part of an image without losing detail. With cameraphones, it’s typically the case that only digital zoom is supported on the handset (zooming in will cause you to lose detail).
When capturing photos at a higher resolution, it becomes possible to crop your image and to have enough pixels leftover for a good-quality print (e.g. you’re able to crop a 5 megapixel section from your 34 megapixel image). This isn’t possible when capturing photos at a lower resolution.
The Lumia 1020 captures widescreen photos at 34 megapixels (7712 x 4352 pixels). With so many pixels, you’re able to crop a small section from the image (e.g. a 5 megapixel section from the centre of the image). For more information, see the Lumia 1020 review. Image source: Nokia.
Disadvantages of Having More Megapixels
Having more megapixels isn’t always good news – it increases the size of your photos and the amount of system resources required to open the file (e.g. RAM and processing power). Having more pixels on a sensor of the same size will also require pixels to physically get smaller. As each pixel will capture less light, there’s reduced sensitivity in low-light conditions. Dynamic range will also be reduced and the resulting images may contain more noise (the extra pixels will create thermal noise).
Your Thoughts…
For many people, the camera is the most important feature when buying a new smartphone. The number of megapixels is one of the most common ways of comparing smartphone cameras.
Throughout this article, we’ve explored the concept of a megapixel. We’ve outlined the number of megapixels you actually need in daily life (e.g. for social media and for printing). We’ve also explored the benefits and disadvantages of having more megapixels (e.g. being able to crop and print your images against having larger file sizes and reduced dynamic range).
Are you a fan of higher megapixel cameras or do you prefer fewer megapixels as on the HTC One M8? How many megapixels would your perfect cameraphone have? We’d love to hear your thoughts: please drop us a comment below and let us know what you think!
Ken Lo writes about mobile technology and the mobile industry at Ken's Tech Tips.