For millions, a smartphone is a portal to work, social connection, and entertainment. But for a significant minority, using one can be a literal headache. The culprit? A common screen technology called Pulse-Width Modulation (PWM), which can cause eyestrain, nausea, and headaches in sensitive individuals.
With the release of iOS 26 and the new iPhone 17, Apple has officially acknowledged this issue for the first time by introducing a new setting dubbed "Display Pulse Smoothing." On the surface, it’s a welcome move. But as our testing and user reports indicate, this well-intentioned feature is, in its current form, more of a band-aid than a cure.
Understanding the Flicker You Can’t See
To grasp why "Display Pulse Smoothing" is a big deal, you first need to understand the problem it's trying to solve. Most modern smartphones, including iPhones, use OLED displays renowned for their deep blacks and vibrant colors. To control brightness, many of these screens use PWM.
Think of PWM not as a dimmer switch that smoothly lowers power, but as a digital switch that turns the display on and off at lightning speed. At full brightness, the "on" pulses are long. As you lower the brightness, the "off" periods become longer. The average of these rapid cycles is what your brain perceives as a dimmer screen. The rate at which this switching happens is the PWM frequency.
The issue arises with low-frequency PWM, typically below 500 Hz. While the flickering is too fast for the conscious eye to see, the visual cortex of sensitive individuals can still detect it, leading to the unpleasant symptoms many report.
Apple’s Answer: What is Display Pulse Smoothing?
Tucked away in Settings > Accessibility > Display & Text Size in iOS 26, you’ll find the new "Display Pulse Smoothing" toggle. Apple’s description is characteristically vague, calling it an "alternative method for dimming the OLED display."
This has led to speculation within the tech community. As detailed in our comprehensive Apple iPhone 17 review, the manufacturer is likely implementing a form of DC dimming or a hybrid solution. Unlike PWM's rapid on/off pulses, DC dimming works by directly reducing the power to the display pixels, theoretically eliminating flicker entirely.
YouTuber Nick Sutrich has theorized that Apple may be using something called Pulse Amplitude Modulation (PAM). Instead of changing the pulse width, PAM changes the voltage level (amplitude) of the signal, creating a smoother, sine wave-like curve rather than a jarring square wave. This aligns with the "smoothing" name and our own measurements, which show a significantly flatter frequency response when the feature is active.
The Crucial Caveat: Why This Feature Has Limited Impact
Here’s where the excitement meets reality. Our testing confirms a major limitation: Display Pulse Smoothing only functions up to approximately 25% screen brightness. The moment you push the brightness slider beyond that point, the iPhone 17 reverts to standard PWM dimming.
This severely restricts the feature's utility. In a brightly lit office or outdoors, 25% brightness is often unusable. Furthermore, technical analysis suggests that even when active, the underlying dimming frequency and modulation rate—key factors in triggering PWM sensitivity—remain unchanged from the standard mode.
The Verdict from the Most Important Critics: Users
Ultimately, the most telling feedback comes from those the feature is designed to help. On online communities like the Reddit subreddit r/PWM_Sensitive, the initial hope has been tempered by disappointment. Numerous users who identify as PWM-sensitive have reported experiencing the same familiar symptoms of eye strain and headaches even with "Display Pulse Smoothing" enabled.
The consensus is that while Apple's move is a step in the right direction, the implementation is not yet robust enough to make a tangible difference for those most affected by display flicker. The combination of the low brightness ceiling and the unchanged fundamental dimming characteristics appears to nullify any potential benefits for a large portion of the sensitive population.
Looking Ahead: A Foundation for the Future?
The introduction of Display Pulse Smoothing is a clear signal that Apple is listening to a segment of its user base that has long felt ignored. It establishes a software-based framework for addressing PWM sensitivity, which is a positive development.
The hope now is that this is a Version 1.0 feature. The foundation is laid, and with future iOS updates, Apple could potentially expand the brightness ceiling, refine the alternative dimming method, or increase the base PWM frequency across the board.
For now, while the iPhone 17's new setting is a commendable acknowledgment of a real problem, it's unlikely to be the definitive solution that PWM-sensitive users have been waiting for. They may still need to hold out hope for a more effective software update—or perhaps, the next generation.
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