We've long grown accustomed to modern smartphones being equipped with multiple cameras. In addition to the main and ultra-wide-angle lenses, modules often include depth sensors and monochrome sensors that help improve the final image. But in recent years, another type of auxiliary module has been appearing more frequently in smartphones — the spectral sensor. What is it and why is it needed?

What is color and why is it difficult to reproduce accurately?

From school physics, we remember that light is an electromagnetic wave of varying lengths. The human eye is capable of perceiving only a tiny fraction of the spectrum — about 0.005%. Everything we call color lies in the range from red to violet. Infrared, ultraviolet, and other radiation are invisible to us.

Conventional smartphone cameras are even more limited. Most of them use RGB (red, green, blue) or RYYB (red, yellow, yellow, blue) color filters. These filters only allow certain wavelengths to reach the sensor. As a result, the camera receives incomplete information about the true color of the object. This leads to sometimes unnatural shades, especially in complex lighting.

How spectral sensors work

Spectral sensors, such as SpectraVision in Tecno smartphones or the module in Huawei's XMAGE system, operate on a fundamentally different principle. Instead of rigid color filters, they use a spectrometer that splits light into many narrow bands of different wavelengths.

The resolution of the spectral sensor itself is usually low — it is not intended for taking photos on its own. Its task is to collect the most accurate data possible about the actual spectral composition of light falling on the object. The image signal processor (ISP) then uses this information to correct the image from the main camera.

The result is colors that become noticeably more natural, closer to what the human eye sees in real life.

A simple way to test it

Want to see the difference for yourself? Cover the spectral sensor on your smartphone with your finger (usually a small module next to the main camera) and take a photo. The color reproduction will change immediately — often for the worse. The effect is especially noticeable on complex surfaces: skin, fabrics, plants, or objects with a metallic sheen.

Why manufacturers need this

Spectral sensors allow smartphones to reach a new level of color reproduction, especially in mixed lighting conditions or when shooting objects with subtle shades. This is important not only for amateur photography but also for professional tasks: design work, retouching, creating content for online stores, and even medical skin diagnostics.

For now, such modules are mainly found in flagship and sub-flagship devices, but the trend is clearly gaining momentum. Manufacturers understand that in an era when photo and video have become the primary means of communication, color realism is one of the key competitive advantages.

In brief

Spectral sensors in smartphones are the next step beyond RGB filters. They split light into many narrow bands and provide the processor with accurate data about the true color of objects. As a result, images come out significantly more natural, especially in challenging lighting conditions. The technology is already used in models from Tecno, Huawei, and other brands, and is gradually becoming an important element of flagship photography. In the future, such sensors could open up new possibilities not only in photography but also in other fields.