What is DC Dimming in AMOLED and why is it being added to AMOLED Smartphones?

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What is DC Dimming in AMOLED? Is it something new? Does my device have this feature? How do I use it? Let’s understand it and answer all of your questions.

Dimming or brightness in a screen panel is generally handled in two ways – Pulse-Width Modulation(PWM) Dimming and DC Dimming. PWM Dimming is the default way brightness is handled in AMOLED screens. This is because it is easier to implement, gives more accurate colors, is cost-effective, and is more energy-efficient. But, DC Dimming is not something new and has always been used in older LCD screens. Why is this old technology coming to new smartphones though? Let’s break down PWM and DC dimming.

PWM Dimming breakdown

Up until recently, most AMOLED displays used PWM technology to control the screen brightness. The term itself is very self-explanatory. The display will alternate between being on and off at different rates but to the naked eye, it seems like the brightness has been decreased since less light reaches our eyes.

For 100% brightness, the screen always remains on. For 50% brightness, the screen remains on for half of the unit time, and for 25% brightness, the screen remains on only for 1/5th of the unit time.

pwm-display-cycle

Ideally, the rate of this alternation is so fast that we can’t determine it but as we decrease the brightness further, the PWM reaches as low as 60 Hz, which many people with more sensitive eyes can see. ( Ever notice the continuous flickering in fluorescent tube lights? This is similar.)

Usually, PWM can hit a rate fast enough that it isn’t a problem for most people, but it causes problems ranging from eye strain to headaches for those that it does affect. If your device has DC Dimming, though, none of this is a problem.

DC Dimming breakdown and it’s AMOLED tradeoff

In DC Dimming, the display stays on most of the time and the current is continuous, but the voltage or current going to the displays is reduced. This constant illumination gets rid of any issues which may be caused by the rapid flickering of the display. It allows displays to lower their brightness to far lower levels but it may also cause some heating issues as lowering the DC voltage requires dissipating the voltage drop as heat.

However, it is not easy to implement for AMOLED screens. This is because, in AMOLED displays, each pixel is powered separately, and reducing the voltage or current through these OLEDs also causes a shift in color, decreasing the image sharpness and overall quality.

To summarise DC Dimming

Advantages of DC Dimming in AMOLED

  • It allows for lower levels of brightness as compared to PWM Dimming.
  • There is no flickering in DC Dimming, which might help those with eye strain or headaches caused due to PWM Dimming in displays.

Disadvantages of DC Dimming in AMOLED

  • It is less a energy-efficient alternative to PWM Dimming.
  • It generates a bit of heat due to the voltage dissipation when lower the brightness.

How to enable DC Dimming on supported phones?

Most of the phones have the setting named DC Dimming, Anti-flicker, or Flicker-free and can be searched in the phone settings.

On Color OS phones from Oppo and Realme this is under Settings>>Display & Brightness. Here toggle on the “Low-Brightness Flicker-Free Care” option.

color-os-oppo-realme-dc-dimming-setting

On Xiaomi phones, go to display settings and turn on “Anti-flicker mode”.

xiaomi-dc-dimming-setting

On OnePlus phones, this setting is in the OnePlus Laboratory under the Utilities option in Settings.

oneplus-laboatory
dc-dimming-on-oneplus

On the OLED phones that this option is not present, you can use apps like PWMfree. It speaks of itself to be “A simple application that uses a transparent overlay to dim the device brightness, effectively removing PWM.”

pwmfree-icon

Download PWMfree

If you are having no issues with PWM, you should continue using it as it delivers a greater experience, but this is surely something that people sensitive to flickering will appreciate.

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