In recent years, the capacity of smartphone cameras has been growing steadily. Initially 48-megapixel sensors appeared in the world, then came the turn of sensors with 64-megapixel capacity, and now nobody is surprised by the use of monster 108-megapixel cameras in smartphones. But while earlier, the increase in the capacity of the camera was inevitably due to the increased detailing of the images, the current generation of 108 MP sensors has a completely different goal.How Pixel Size Affects Photographic Quality
Each camera sensor is made up of critical pixels that capture light and are measured in microns. For example, the smartphone Xiaomi 11T recently arrived in Ukraine, uses a 108-megapixel sensor Samsung Isocell HM2 with 0.7 μm pixels, and the Samsung Galaxy S21 FE has a 12-megapixel sensor with 1.8 μm pixels.Taking a superficial approach, it is easy to see that the more pixels a camera's sensor has, the more detailed the pictures are likely to be. But the size of any sensor, especially the sensor of such a compact gadget as a smartphone, is extremely limited. And what will happen if you place a different number of pixels on the same space? The more pixels are located there, the less their size will appear, which, by the way, is well seen in the above application.And here banal physics comes into play. Consider two windows of 0.5 and 1.5 square meters. Which one will bring more light into the room? Certainly more. So with pixels: the bigger the size, the more light it is able to capture. You are unlikely to feel a special difference in ideal shooting conditions, but on a foggy day, at night, sensors with more pixels will give just a great win in the image.Pixel binging
So why manufacturers so diligently increase the number of pixels in the cameras of their smartphones to the detriment of their size? The point is that modern camera sensors support the technology of pixel binning, or, more simply, the integration of neighboring pixels into one large "superpixel".
For example, Xiaomi 11T, which we have already seen, uses a 108-megapixel sensor Samsung Isocell HM2 with pixels, the physical size of which is limited to a modest 0.7-μm. If everything remained so, the light sensitivity of such a sensor would be minimal, i.e. it could take good pictures only in ideal conditions.However, thanks to the 9-in-1 pixel binning technology, the smartphone is able to combine up to nine neighbouring pixels, due to which the effective pixel area increases to 2.1 microns, which, incidentally, is even greater than that of the Samsung Galaxy S21 FE with its "stock" 8-μm pixels. Consequently, its light sensitivity increases, and at the same time the noise is reduced and the quality of imaging in low light increases.
The principle of the technology is as simple as possible. Each pixel of the sensor captures only the light and its intensity without any color variations. To obtain complete photographs, the sensors use color filters that allow only light from a certain part of the spectrum (color) to pass through to an individual pixel. Thus, some pixels take only black color, others - green, and others - blue.But this is the case with the conventional matrix. As for the technology of pixel binning, it involves using one filter not for an individual pixel, but for their group, which allows them to work as a single unit. And the number of pixels in such a group can be different. In our application, one filter "covers" 9 pixels - the technology is called 9-in-1. In 48-megapixel cameras, for example, 4-in-1 technology is often used, combining four sub-pixels. In both cases, the photographic capacity is the same - 12 megapixels.However, manufacturers are well aware that the technology of combining pixels is not always necessary, and sometimes the maximum detailing of the photo is important for users. That is why most smartphones with the technology of pixel blinking have a shooting mode in the maximum separation capacity. It wins in pixel binning at the time of shooting on a bright sunny day, but without a chance to lose to it in difficult lighting conditions.
Findings
Increased separation capacity of modern smartphone cameras allowed us to use the technology of pixel binning - virtual integration of neighbouring pixels into one "superpixel". Well, increasing the density of the pixel, in turn, made it possible to increase its light sensitivity and improve imaging quality in conditions of insufficient illumination.
But, of course, the 108 megapixel camera is not always better than a 12 megapixel one. Besides the size of the pixel light intensity depends on the quality of optics, aperture size and other parameters. Nevertheless, the technology of pixel binning is rightly regarded as an effective and inexpensive way to improve the quality of photography.
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