AMOLED screens and the unnecessary wasting of battery power

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The AMOLED (used in all of the new Symbian^3 and Anna phones, apart from the E6) bottom line is that, because every pixel provides its own light, a bright/white display uses up to fifteen times as much power as a dark/black one. With battery life being a big issue with modern smartphones, you'd have thought that factors of fifteen would make OS and application designers sit up and pay attention. Alas, no. Here's a look around the Symbian world at what has and (usually) hasn't been done to take AMOLED's characteristics into account.

Although there are other big battery drainers on a modern smartphone - cellular data, GPS and camera spring to mind, the display is usually right up there when examining the data using the likes of Nokia Battery Monitor. And yet it really doesn't need to be - moden AMOLED screens can be incredibly efficient. Just look at the always-on AMOLED screen saver clock on your Symbian^3 phone - it's there 24 hours a day and doesn't seem to impact battery life at all.

The biggest way to use an AMOLED display to draw power is to ask it to light up all its pixels in white (as mentioned, up to around fifteeen times as much power in a typical application, compared to the same app displaying a mainly black screen) - which you'd have thought would be a clarion call for all OS and application developers to write their user interface with this in mind.

You can tell that some developers are aware of this, and credit to them. For example, Gravity (below, left) has a 'Dark' theme that works superbly, while Nokia's default themes for their Symbian^3 and Anna handsets are themselves black/dark (below, right), witness the 'Midnight...' series of themes to choose from.


Screenshot Screenshot 


So far so good. Using Symbian on a dark themed phone is no problem at all and should result in far longer battery life per charge. But most of your time on your smartphone will be spent in the core applications, so we need those to toe the line too. Let's look at some of the main problem apps, in turn, in each case giving them an AMOLED efficiency rating, where 100% is as power efficient as possible.

Ovi Maps

AMOLED rating: 10% (i.e. wasteful)

An application that is often run at full brightness for long periods of time, Ovi Maps is only accidentally compliant with AMOLED power-saving philosophies, by virtue of having a 'night mode', shown below, for interest sake. Of course, 99% of users won't know about this and the default is the familiar 'day' mode, with white background and brightly coloured roads.




There's no doubting that the normal 'white' Maps theme looks better and is easier to read, but a few extra pop-up hints from Nokia, pointing out the benefits of the dark 'night' mode, or even a proper daytime dark theme would be a great step forwards.

That the power efficiency of Ovi Maps hasn't come up so far is probably because navigation is so power hungry anyway - most users would use it while plugged into the car's 12V - hopefully!

Nokia Email

AMOLED rating: 60% 

On Symbian^3 phones, Nokia Email now respects your phone's theme - so the message summaries, menus and dialogs are all dark. However, Nokia Email then goes and shoots itself in the foot by insisting on displaying even plain text emails with dark text on a plain white background. I can understand this for HTML email, where the recipient may have wanted artistic text and images on a white 'paper-like' backdrop - but surely it's wasteful for plain text.


One saving grace is that at least the editing window, used for typing your replies, is back to respecting the phone's (dark) theme. 

Nokia Social Networking

AMOLED rating: 5% (i.e. horrendously wasteful)

A recent addition to the Symbian canon in Nokia's Symbian^3 phones, Nokia Social is a Web runtime-based multi-network social client that actually works quite well in terms of contact integration and media sharing. And, for a general purpose Facebook and Twitter client, it's not bad. The main complaint about Nokia Social is that it's slower than a native Symbian C++ or Qt-written application. Which is fair comment, but I have a complaint that's just as big: it's appallingly ignorant of AMOLED screens - everything within the entire Nokia Social interface, from timelines to message composition to media sharing, is all presented in a white themed interface (below, left), for no good reason whatsoever

A quick and dirty mock-up, below right is a rough equivalent of how Nokia Social would look if Nokia's programmers switched it to a dark theme. Leaving aside my clumsy Photoshop skills, it's clear that white-on-black can be just as readable as black-on-white, yet with huge battery implications. I've been railing at Nokia Social's programmers to fix this since day one - and I'm still waiting...


Screenshot Screenshot 


Nokia Social 1.3 is the version to go for at the moment, officially only available through the Ovi Store - but let's hope that the much trailed version 1.4 finally has the black theme that's drastically needed.

Ovi Store

AMOLED rating: 5% (i.e. horrendously wasteful)

As with Nokia Social, and built largely on the same Web runtime core, the Ovi Store client is horribly inefficient in terms of display colours. It's almost entirely white or light grey and a battery disaster. At least you're unlikely to spend more than an hour a week IN the Store client, but even so...





AMOLED rating: 20% (i.e. wasteful, but not much you can do)

Ah yes, Symbian's much maligned Web browser. It's actually not that bad for many sites, but here we're thinking about its display efficiency. And here, unlike in Email, there's little that can be done about page colouring. Just as with a page in a magazine, web pages are designed to appear in a certain way and Web's job is to display them as-is. 

The problem is that most web pages look far better, across all monitor and screen types, with black text on white background. In theory, you could design a mobile version to use a dark theme with white text, but few sites bother. And the site designers really want all pages to carry a similar look and feel rather than switching from white on the desktop to black on the phone, etc.

Here's an example of a mobile site which has been designed to be mobile-friendly, thankfully. Yes, it's slightly harder to read than black on white, but on the plus side you can take your time reading it without being aware that your battery charge is literally burning away as you stare!



Third party applications

Thankfully, most third party applications (especially those written by established software houses like Epocware, Smartphoneware and SPB) respect your system theme and put up their UI elements using your preferred dark shades, so you don't have the same issues and worries as with the Nokia add-ons, above!

There are exceptions, of course, where some third party applications toe the Nokia line in that they 'ape' the likes of Nokia Social, with the obligatory white backdrops that look nicer but behave like gluttons. Vote with your feet if you find such an app, tell the developers to look at your system theme and then move onto a different app.

If, like me, you're looking for software that is efficient and can be left on-screen without battery worries, here are a few apps loaded on my own E7 that come with, or work well with, a dark theme:

  • Gravity, Twitter, Facebook and 4Square client
  • X-plore, the best Symbian file manager bar none
  • TwimGo, a new Twitter client



The important thing here is not that I'm being picky about specific screens or apps - each application may only be used for half an hour a day, but when you get five apps, each at half an hour a day and each with white screens or themes for much of that, you'll wonder where on earth your battery has gone. And needlessly gone, in some cases. At the very least, I'd like to see Nokia Social Networking switched to working black on white, ideally as a default, with white-on-black as an option for people who insist on the original colours.

Programmers will pipe up at this point and correctly state that switching an app from white to black isn't just a case of switching a line of code to reference a new colour - there are implications in changing or improving icons and other screen furniture to still look good on a black backdrop. But I contend that the effort needed is still fairly minimal and the potential power benefits for millions of owners are huge.

I should note that Nokia is by no means the only culprit here - plenty of Android smartphones now have AMOLED screens and yet are stuck with Twitter, Facebook, Google Maps, Android Market and other apps that all default to white backdrops. With exactly the same power issues.

Am I just a voice crying out in the wilderness? Surely all this isn't rocket science to grasp? Comments welcome - maybe we can get Nokia and app developers to sit up and pay attention?

Steve Litchfield, All About Symbian, 24 June 2011