You are about to change your smartphone and you would like a particularly powerful model to take photos, do not stop at the number of pixels! Even if the number of megapixels contributes to the final quality of an image, other parameters come into play. Here are our tips for finding your way around.

Since the advent of digital, manufacturers of cameras or smartphones have been engaged in a battle of numbers with large pixel strokes. Systematically highlighted by advertising, the number of pixels is not everything. It is one indicator among others to assess the capabilities of a digital camera.

1. What is a pixel?

To capture an image, digital cameras or smartphone cameras are equipped with a sensor on which microscopic light-sensitive photoelectric cells (diodes) are placed side by side.

Each of these cells, called photosites, transforms what it has captured into a more or less luminous colored point which is displayed on the screen. It’s the pixel.

All of these pixels placed side by side make it possible to restore the image captured by the photosites, as when creating a pattern on a mosaic with small squares. Technically, we should talk about photosites for the sensor of a device and pixels for the screen. But as each photosite makes it possible to display a pixel, it is the word pixel which is used, both for the sensor and for the image.

The importance of the number of pixels

To take the example of a mosaic, for it to have enough detail, it must have a sufficient number of tiles. Early digital cameras lacked the pixel count to rival traditional film photography. This is why pixel count became such a hot topic and a legitimate selling point at the time .

Every technological advance that increased the number of pixels effectively increased the number of details in digital images and directly contributed to the quality of mobile phone cameras.

1 megapixel = 1 million pixels

Today, the miniaturization of components as well as the advent of various technologies make it possible to design sensors comprising so many pixels that it was necessary to move to another scale. From now on, even the most basic smartphone is equipped with a sensor comprising several million pixels, which is counted in megapixels.

If, for example, a sensor has 4000 pixels in width and 3000 in height, it will have a total of 4000×3000 pixels, that is to say 12,000,000 pixels or 12 megapixels. Depending on the manufacturer, we can find the indication 12MP, 12 Mpix or 12 Mpx, but it is the same thing. 1 megapixel = 1 million pixels .

2. The pixel is not everything!

From one model to another, we can meet smartphones whose main sensor is equipped with 8, 12 or more than 100 megapixels. Does a 100 megapixel sensor produce images 10 times more detailed than a 10 megapixel sensor? No, that would be too easy .

To some extent, a very high pixel count can be an indicator, but there are other things to consider . To ensure that their devices produce the best quality images possible, smartphone manufacturers use a variety of strategies. Like the ever-expanding market for digital devices, there is no one way to design a smartphone and technologies are always evolving.

Sensor sizes

When looking at the amount of megapixels present on a sensor, we must also take into account the size of this sensor .

When the sensor is particularly small, placing a large number of photosites on a restricted surface creates interference. In the picture, this results in “  digital noise  ” which blurs the outline of the details and the colors of the picture.

In addition, the size of the photosites (or pixel size) may vary. A large sensor will accommodate larger photosites. These will absorb more light, they will produce more data and the quality of the photos will be even better, including in low light when the lighting conditions are not good. This size is expressed in microns (µm) and can vary from simple to triple, from 0.8µm for the smallest to 2.4µm for the largest .

In fact, the size of the photosites is so decisive for the quality of an image that many smartphones are equipped with a technology called pixel binning (Quadpixel at Sony, Tetracell at Samsung and Xiaomi). It consists of grouping several pixels (3, 4, 9 depending on the technique) together to create a larger “super pixel”. When this mode is activated, the image is better, but quibbling, it amounts to dividing the number of pixels compared to what is announced by the manufacturer. For example, on a Xiaomi mi 11 or a Samsung S21 whose sensor is 108MP, a photo taken with a pixel binning mode will ultimately be 12MP to 16MP.

When the information is available on the data sheet of the camera of a phone (or a camera) and that one hesitates between several models, it is better to take the one with the largest sensor size and the largest photosites . A large 8MP sensor will produce better images than a smaller 12MP sensor.

What kind of picture?

Since we are talking about choice, remember that an important criterion when buying a photophone is the purpose of its use . The lenses will determine the type of image that the camera will be able to produce.

The wide angle is ideal for landscapes (but not essential), the zoom is designed for close-ups. It is also perfect for portraits because it does not distort the subject. It is necessary to privilege the optical zoom , because a digital zoom amounts to cropping the photo. In this case, it is better to do it with specialized computer software which will always be better than any on-board digital zoom.

However, if you want to go through a digital zoom, a sensor of 12MP or 16MP minimum is preferable. Finally, let’s mention the macro lens, which is used to take a close-up photo of small objects.

What image size?

An image that has a lot of pixels takes up more space and will be more cumbersome to process. It will require that the smartphone be equipped with a high-performance processor , which will increase its price.

If the images are intended to be viewed on a TV or computer screen, 8MP to 10MP are sufficient and even less if they are viewed exclusively on the smartphone screen. This number of pixels will also be sufficient to print images up to 30×20 cm.

For 30×40, prefer 12MP and for a 90×60 cm mini poster, 24MP will produce better results.

At the same sensor size, a small difference in the number of pixels is of no consequence. If you’re hesitating between a 12MP or 16MP model and don’t want to print the biggest image possible, take your pick on other criteria to make up your mind.

3. So before making your choice…

The number of pixels is a quality criterion but not the only one . The ideal is to have many large pixels on a large sensor, but this luxury is currently reserved for large format professional cameras that can cost tens of thousands of euros…

To print a good-sized image or crop it without too much loss, we can favor a smartphone with a large number of pixels. But keep in mind that the more pixels the image has, the slower it will be to transfer.

If you do not need to print large or crop, you will choose a device with fewer pixels, but larger, for a better image, more subtle, especially in poor lighting conditions .

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