Google understands that battery ownership will be dramatically improved if the smartphone's UI is set to a black tone 'dark mode'

Some applications for smartphones may have a function to change the UI base color to a darker color such as black, such as "Dark Mode" or "Night Mode". Using such a mode, it is known that it is possible to drastically reduce battery consumption especially for terminals equipped with OLED (organic EL display). For example, iPhone X which is the iPhone's first terminal equipped with organic EL display, it is possible to reduce battery consumption by about 60% by making full use of the dark mode . Likewise, it is clear that with dark mode on Android battery holding is significantly extended, and it is clear that Google finally understood this.

Google's big Android battery 'oops' and future Dark Modes - SlashGear
https://www.slashgear.com/googles-big-android-battery-oops-and-future-dark-modes-08553037/

Google confirms dark mode is a huge help for battery life on Android - The Verge
https://www.theverge.com/2018/11/8/18076502/google-dark-mode-android-battery-life

In Google 's developer summit "Android Dev Summit", Google talks to application developers about what applications can do to improve smartphone battery ownership. The biggest factor in battery consumption of smartphones is "display brightness", which means "color of objects on the screen" will also be greatly involved.

The following slide shows how much power is consumed by screen brightness. The vertical axis shows the power consumption and the horizontal axis shows the screen brightness. The graph shows the result that the power consumption increases as the screen becomes brighter and the result that battery reduction becomes faster.

Subsequently, the following figures compare current consumption when opening a Google map and shooting a screen shot with the original Google Pixel that adopted AMOLED which is one type of organic EL display and iPhone 7 with a liquid crystal display. The brightness of the display is maximum, and it is investigating in both normal mode and night mode. Then, the iPhone 7 of the liquid crystal display does not change the current consumption even if the mode is changed, but it can be seen that Pixel of the organic EL display can greatly reduce the current consumption by using the night mode.

The following graph compares how much power consumption changes with colors displayed on the screen. It seems that you can suppress power consumption by using dark eye color such as violet or blue.

The graph below shows how to maximize the Pixel display brightness and compare the current consumption for each screen color. It is obvious from the left that the color of the screen is black, red, green, blue, white and big differences are born by color.

From these results, Google acknowledged that it was a mistake that we recommended developers to make white as the basis of Android's material design guidelines.

However, at the time of writing the article, please be aware that in the information site on Google's material design, white is contained in "material color theme to be the baseline".

Google seemed to have understood the value of dark mode firmly before showing on the slide that the power consumption changes greatly depending on the brightness and color of the screen, and in major applications such as YouTube already have "Dark theme" and " Night theme "and so on.

I actually paused the movie with the YouTube application and examined how much current consumption differed between normal mode and dark mode is shown in the figure below. As for how much current consumption can be suppressed by setting it to dark mode, it can be reduced by 14% when the screen brightness is 50% and by 60% when the screen brightness is 100%.

As you can see, there are a number of individual apps that adopt dark mode, but the fact is that Android's system has not been compatible with the whole system. The original OS " One UI " under development by Samsung is planned to be able to apply the entire system to the dark mode at once.

Although it is not a mobile OS, since Apple 's latest macOS' macOS Mojave 'corresponds to UI' s dark mode, there is a good possibility that dark mode will be adopted even by the same Apple iOS.

'MacOS Mojave' announced, dark mode appeared in UI, enhanced security function, planning cross-platform with iOS application development - GIGAZINE