The manufacturers of digital system cameras and smartphones are advertising ever higher pixel counts for their camera sensors. But does a lot really help a lot? Do extremely large numbers of pixels really add that much value to photos? It is often said that many megapixels are good for photo representation. But whether that’s really the case and what values like pixels, dpi, etc. are all about, we’ll explain in this article.
What is a megapixel?
The number of pixels that a camera sensor can record is specified in megapixels. A single pixel is a pixel that contains color information. Many of these individual pixels together form a raster graphic, which ultimately makes up a photograph. One megapixel means one million pixels (which is not mathematically correct, exactly it is 1,024,000 pixels). You know from a TV screen the 1080p format, the number of pixels here is exactly 2,073,600, which is about two megapixels. In a digital camera with 24 megapixels, each individual sensor point is counted – and there are three of them, namely one each for the colors red, green and blue.
What does dpi mean?
This unit is often used for printers, but also has an important meaning in photography. The dpi value describes how many pixels are contained in a defined area – in this case “dots per inch”. This already shows that the megapixel value of a camera alone does not mean much. A photo from a 6-megapixel camera (this corresponds to 3000 x 2000 pixels) looks razor-sharp on 13×18-cm photos. However, when the same photo is printed at poster size, the whole thing literally looks “pixelated” even though it contains the same number of megapixels. And this is where the dpi value comes in, because it describes how close together the pixels are. A camera can produce as many megapixels as it likes, but if too few “dots per inch” are used in printing, you can see the individual pixels in the final product.
What is a good or sensibly high resolution?
Always be aware of the following: A high resolution in megapixels in a camera does not necessarily mean that the photos will be better! Often the opposite is the case. Especially in the field of hobby photography, as many megapixels as possible have been advertised over the past 20 years, and even today smartphone manufacturers print a big “40 MP” or more on their packaging. But photo resolution is not all that determines the quality of photos. Indeed, the size of the camera sensor (here, terms like “APS-C”, “full-frame” or “Micro 4/3” are well known) is also important. A very large number of pixels in a very small space (here especially with the tiny camera sensors in smartphones) often lead to the dreaded color noise, especially in low light conditions – at the latest when you push the ISO value into the four-digit range.
With a current 24-MP camera, dedicated photographers produce first-class photo material, especially when these are printed on a photo printer with at least 300 dpi. And there are already interest groups like the “Six Megapixel Club” that go back to a 6-MP limit and still develop professional-quality photos with a Pentax K100D from 2006.
Smartphone with 108 MP camera – what is that?
Phones like the Samsung Galaxy 20 series or the Xiaomi Mi 10T Pro have a camera sensor with 108 MP on board. It might sound richly exaggerated at first after the aforementioned remarks to push 108 million pixels to fingernail size. What is wrong here? No, nothing is artificially inflated here for the sake of marketing: The 108 MP are actually physically present. The so-called pixel binning is used here. Here, the pixels are combined into groups of four, which leads to a much higher light sensitivity. This means that the photo resolution is actually only around 24 MP, but night shots in excellent quality are possible with these cameras. In this case, extremely many megapixels are actually useful.
