Camera

 If you’ve ever purchased a new camera or smartphone, you’ve probably heard the term “megapixel.” Basically, it’s a way to quickly describe a camera’s resolution based on the number of pixels it’s capable of capturing.

One megapixel refers to one million pixels, which are small squares of information that combine to make up an image. So, if a camera has a resolution of eight megapixels, it would be able to capture images with about eight million tiny squares of information per inch

Most smartphone brands usually refer to their device’s megapixel count when discussing their photo quality — and newer phone models typically come with improved cameras that feature more megapixels. For example, the cameras on Samsung’s Galaxy S5 and Galaxy S6 both come with 16-megapixel sensors, while the Galaxy S4 featured a 13-megapixel camera. The iPhone 6s and 6s Plus both have 12-megapixel cameras, an improvement over older iPhones’ 8 megapixels.

The way megapixels are touted by brands in their ads can lead some people to believe that a higher number of megapixels always means better photos. That may be true sometimes. But it isn’t always the case, according to Nikhil Bhogal, the founder and CTO of June, which makes a smart oven of the same name. Before cofounding June, Bhogal was a software engineer at Apple where he worked on camera technology for the iPhone.

Bhogal says pixel quality matters more than the actual number of pixels in a camera sensor, especially when it comes to smartphone cameras. “Even in a tiny picture, you can pack in a lot of good quality information,” says Bhogal. “You don’t have to take a 40-megapixel picture to have that much information.”

Camera Resolution:

• Print Size – usually the most important factor. Basically, the more resolution, the larger the potential print size. Printing from digital images is accomplished by squeezing a certain number of Pixels Per Inch (PPI). A high quality print with good details usually involves printing at around 300 PPI, so the size of the potential print is calculated by taking image width and height and dividing them by the PPI number. For example, a 12.1 MP resolution image from the Nikon D700 has image dimensions of 4,256 x 2,832. If you wanted to create a high quality print with lots of details at 300 PPI, the print size would be limited to approximately 14.2″ x 9.4″ print (4,256 / 300 = 14.2 and 2,832 / 300 = 9.4). Larger prints would be possible, but they would require you to either drop the PPI to a lower number, or use special third party tools that use complex algorithms to upscale or “up-sample” an image to a higher resolution, which do not always yield good results. In short, higher resolution is usually more desirable for the ability to print larger.
• Cropping Options – the higher the resolution, the more room there is to potentially crop images. Although many photographers avoid heavy cropping, sometimes it is necessary to focus on the desired subject(s). For example, sports and wildlife photographers often resort to cropping, because they might not be able to get closer to action, but at the same time do not want their final images to contain unnecessary clutter surrounding the main subject(s). As a result, they often employ heavy cropping, which ultimately reduces resolution, which is why they tend to desire as much resolution as possible and practical.
• Down-sampling – as I have previously explained in my article on the benefits of high resolution sensors, the higher the resolution, the better the options for resizing or “down-sampling” images. As I will explain further down below, modern high resolution cameras have similar performance as their lower resolution counterparts, but their main advantages are the ability to down-sample to lower resolution to decrease the amount of noise and when shooting at low ISOs, the ability to yield larger prints.

Display Size – during the past 10+ years, we have seen a significant progress is display technology. Monitors, TVs, projectors, phones, hand-held and other devices have seen big increases in resolution and the increased space on those devices naturally led to the need to show higher resolution images with more details. 4K monitors and TVs (over 8 megapixels) are getting more popular and common, which puts more burden on cameras to yield images with enough details to showcase on such high resolution devices.

Judging from the above, it seems like higher resolution is always better. But that’s certainly not the case, because it is not just about the quantity of pixels, but their quality. Further down below, I will explain what this means in regards to sensor size, pixel size, lens resolving power and technique.

Camera Resolution: How Much More is X MP vs Y MP

When Nikon first introduced its D800 / D800E cameras with 36.3 MP resolution full-frame image sensors, many photographers were still shooting with 12.1 MP full-frame cameras like Nikon D700 and D3 / D3s. Doing simple math, many claimed that the 36.3 MP sensor represented 3 times more resolution (12.1 MP x 3 = 36.3 MP) and some wrongfully assumed that upgrading to a camera like D800 would yield 3 times bigger prints. While the total number of effective pixels indeed is three times larger when comparing 36.3 MP vs 12.1 MP, the difference in linear resolution is actually far smaller. That’s because sensor resolution is calculated by taking the total number of horizontal pixels and multiplying it by the total number of vertical pixels, similar to how you calculate the area of a rectangle. In the case of the D700, which has an image size of 4,256 x 2,832, the sensor resolution equals 12,052,992, which rounds to approximately 12.1 megapixels. If we look at the Nikon D800, its image size is 7,360 x 4,912 and hence the sensor resolution is 36,152,320, roughly 36.15 megapixels (the discrepancy between 36.15 vs 36.3 comes from the fact that some of the pixels, such as optical black and dummy, around the edges of the sensor are used to provide additional data).

Now if we compare the total number of horizontal pixels between the D700 and the D800, it is 4,256 vs 7,360 – an increase of only 73%, not 200% as wrongfully assumed by many. What does this translate to? Basically, if you could print a detailed 14.2″ x 9.4″ print at 300 PPI with the D700, upgrading to the D800 would potentially result in a 24.5″ x 16.4″ print at the same 300 PPI. Hence, moving up from 12 MP to 36 MP would translate to 73% and not 3x larger prints. Again, it is easy to confuse total area with horizontal width, so it is important to understand the difference here.

In order to yield twice larger prints at the same PPI, you would need to multiply sensor resolution by 4. For example, if you own a D700 and you are wondering what kind of sensor resolution you would need to print 2x larger, you multiply 12.1 MP (sensor resolution) x 4, which translates to a 48.4 MP sensor. So if you were to move up to say the latest Canon 5DS DSLR that has a 50.6 MP sensor, you would get prints a bit larger than 2x in comparison. To understand these differences in resolution, it is best to take a look at the below comparison of different popular sensor resolutions of modern digital cameras from 12.1 MP to 50.6 MP: