Xiaomi Mi Note 2
128 GB, Black, 5.70", Dual SIM, 22.50 Mpx, 4G
True Black - Saving electricity on a low flame
9.5.2017
Translation: machine translated
Processors are getting faster, the resolution on smartphone screens is getting higher, but the batteries remain the same size. The battery is often barely enough for a working day. So every little bit of battery saving is worth a second look. In addition to dodgy apps, there is now a new and stylish way to save battery power: True Black for AMOLED screens.
First things first: In this article, I'm not going to tell you how to optimise the power usage of your smartphone so that the battery lasts for twenty days. But with this little trick, you might be able to save a per cent or five of your battery over the course of the day if you have a mobile with an AMOLED display.
Because the general thing is this: There is no one all-purpose weapon against short battery life. There are optimisations you can make here and there. One of them is your wallpaper and your lockscreen background on an AMOLED display.
In this article, we will therefore look at two things in particular and then, by skilfully working together, find a solution to make your battery last slightly longer. First, we'll look at how AMOLED technology works and then how colours work on screens.
AMOLED, huh?
AMOLED is a screen technology. It stands for active-matrix organic light-emitting diode. German nouns are great.
In an AMOLED display, an active matrix of OLED pixels is installed that generates light through electronic activation. These are integrated into a thin-film transistor (TFT) array that acts as a series of switches. This series of switches in turn controls the flow of current to each individual pixel.
This means that if we can reduce the current flow to individual pixels, less power is consumed in general.
This is exactly where a small but active community of Photoshoppers comes in, trying to minimise power consumption by using True Black in their wallpapers. Because when a pixel is displayed in true black, no electricity flows to it.
The flagship smartphone with an AMOLED display that everyone is talking about at the moment is the Samsung Galaxy S8, but other devices have also discovered the technology for themselves.
True Black: black is not the same as black
So what is this true black? On computer screens, black is not the same as black. A brief comparison.
If you look at this on a technological level, the comparison there becomes obvious when we look at the colour values. Throughout history, a number of number systems have been established that can be used to define colours most accurately. Of these, CMYK and RGB are probably the most widely used.
CMYK black
CMYK is the abbreviation for cyan, magenta, yellow and key, i.e. black. The values are expressed as per cent. So 50% cyan and 50% magenta result in a pale purple colour. In CMYK, the colour would be expressed as 50/50/0/0.
CMYK black is easy to create
- Cyan: 0
- Magenta: 0
- Yellow: 0
- Key: 100
This is what it looks like:
RGB black aka true black
RGB stands for Red, Green, Blue and is optimised for use on the screen. The values are therefore not given as per cent but from 0 to 255. Here, too, the practice RGB 127/127/0 has become established.
RGB black is easy.
- Red: 0
- Green: 0
- Blue: 0
Voilà:
So why is CMYK black a different colour to RGB black? Put simply: CMYK is designed for the printing industry, RGB for screens. Therefore, CMYK black expressed in RGB is 29/29/27, i.e. a darker grey. Conversely, RGB black in CMYK is 91/79/62/97.
There are even more shades of black in the wide world of colours, but I think I have now made the point that "black is not necessarily black".
In practice
It can therefore be concluded that the more true-black a wallpaper is, the less power is used to light up the screen. And the whole thing looks like this in its purest form. If you use CMYK black on your screen, then the pixels are supplied with enough power to glow dark grey.
That's why the Photoshoppers of the Reddit community /r/AMOLEDbackgrounds set out not only to collect AMOLED backgrounds, but also to create them themselves. The results are mixed. Some of the background images are great:
Others, however, are simply cut out more badly than right in Photoshop and pasted onto a black background.
The ultimate solution?
I already mentioned at the beginning that simply changing the background image is not the ultimate solution. After all, as with pretty much all high-tech devices, behaviour on smartphones has more than one cause. In fact, a behaviour can only arise precisely because a number of causes come together that would never have been noticed individually.
The fact is, however, that it is often the screen that eats up the most battery, which is why a nice AMOLED-optimised background image can definitely help.
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Journalist. Author. Hacker. A storyteller searching for boundaries, secrets and taboos – putting the world to paper. Not because I can but because I can’t not.