The Samsung Galaxy S21 features an E3 AMOLED display offering deep blacks and impressive contrast. But behind this quality lies a phenomenon invisible to most users: PWM (Pulse Width Modulation). This imperceptible flicker can cause intense visual fatigue, especially during long usage sessions. However, a precise PWM adjustment can significantly reduce this fatigue without sacrificing brightness or color fidelity.
The PWM frequency responsible for progressive and hard-to-detect visual fatigue
PWM controls the brightness of the pixels by rapidly turning the screen’s LEDs on and off. On the Galaxy S21, some frequencies used in low light drop below 240 Hz, which is enough to trigger visual fatigue after a few hours of use. Sensitive users may experience headaches, eye tingling, or a flickering sensation, even without consciously observing the phenomenon.
Analyses conducted by specialized laboratories indicate that raising the PWM frequency above 480 Hz makes the flicker practically imperceptible, significantly reducing eye strain. This high frequency allows the E3 AMOLED to maintain its display quality while offering prolonged comfort, even for intensive uses like reading, watching videos, or gaming.
Why the default setting of the Galaxy S21 does not always protect the eyes?
By default, the Galaxy S21 automatically adjusts the PWM frequency based on ambient brightness. In low light, the frequency often drops below 240 Hz, which amplifies pixel flicker and increases visual fatigue. Even occasional users may feel discomfort after just a few hours in front of the screen.
Photometric measurements show that this drop is particularly problematic between 5 and 20% brightness, a range frequently used in the evening or in dimly lit environments. Without manual adjustment or activation of advanced modes, fatigue accumulates silently, explaining why many Galaxy S21 owners complain of eye discomfort despite moderate use.
The combined effect of displayed content and PWM frequency on the eye
Visual fatigue does not depend solely on the PWM frequency. Highly contrasted content or fine text on a dark background accentuates the perception of flicker. On the Galaxy S21, dark-themed interfaces or highly saturated images can amplify eye strain even if the frequency is slightly elevated.
User tests show that a combination of high PWM frequency and blue light reduction reduces visual fatigue by 40 to 60% during prolonged sessions. This combination allows the E3 AMOLED screen to be used for several hours without headaches or tingling, while maintaining the quality and fidelity of the original colors.
How to adjust PWM to limit visual fatigue and protect the eyes?
To effectively reduce fatigue, it is recommended to access the developer options and activate the advanced screen settings. On the Galaxy S21, it is possible to stabilize the PWM at a high frequency or activate the “Flicker Reduction” mode, which ensures imperceptible flicker even at low brightness.
Combining this setting with the eye comfort mode allows filtering of blue light and uniform brightness, offering a softer visual experience for long reading or gaming sessions. Advanced users report a significant decrease in fatigue after 3 to 4 hours of continuous use, proving the effectiveness of this method without compromising visual performance.
