Super AMOLED color banding issue: Microsoft could partially fix it

I just did some more testing and am fairly sure now that everything is rendered at 16bit throughout the OS in Windows Phone 7 (similar to WM5/6). The picture you see above shows the image found in this news posted rendered in the Android browser on the Galaxy S (left) and IE Mobile on the Samsung Omnia 7 (right). Keep in mind that both devices have exactly the same Super AMOLED panel. What is evident here is that dithering is applied to the pictures on Android. All you have to do is move the page around on the Galaxy S to see that it’s activated (the color dithering) when the page is standing still but when you scroll or pan the images will look identical to the ones rendered on the Omnia 7 in IE Mobile. So what I did next is save this particular image and then open it in the picture’s browser where I know that dithering is applied once you start zooming in:

Voila! No more nasty banding (well it isn’t all gone but it’s 10x better than before). The third picture below shows the HTC 7 Trophy thrown into the mix:

There’s some banding on the Trophy’s TFT LCD screen but it isn’t as nasty as on the Super-AMOLED (and doesn’t really show up in the picture because of the screen’s brightness sorry). So what’s the solution? Well Microsoft could easily enable dithering in the browser first. Secondly, the best solution would obviously be to have everything rendered in 24bit so applications and games won’t look like crap on Super AMOLED devices…but I guess that this is wishful thinking….

  • BucksterMcgee

    “but I guess that this is wishful thinking….” I sort of feel the same way, but then again I really feel it’s the ONLY lacking thing on my Samsung Focus. Everything else is great, except for the color banding issue.

    The worst part is watching movies on the screen, the color banding really makes lower quality blocks in videos stick out more than they should. If the issue really is color bit depth, then I truly hope they are able to do something to reduce its appearance.

  • Anon

    Thank you for your work on this issue. I have seen colour banding when browing images on the Omnia 7 (in a shop) myself. It really was a shame, as it was particularly bad and the other aspects of image quality seemed so good. What is also a shame is that so far as I can see you are the only person picking up on this issue so far. It really needs addressing and flagging up.

    Could you please explain why Samsung AMOLED needs a greater bit depth in order to display the same smoothness of gradient? In other words, why do LCD panels seem to cope so much better at 16 bit?

  • Anon

    You say in your edit “you assume this and the color banding issue are connected in some way”. Not to annoy you, but perhaps you could have read his article more carefully.

    What I think he is saying is that the perfect way to get better colour gradients is to use a better “bit depth” which allows a greater number of colours. Having more subtle colours allows you to make colour gradients (or fades) smoother. BUT if you are stuck at a certain bit depth, the alternative is to use DITHERING. Dithering simulates a smoother colour gradient by mixing different colours together in a very tiny mosaic to give the impression of a colour equivalent to a mixture of the colours in the mosaic. Thus, if you don’t have the in-between colour you need, you can simulate it by dithering. So that’s dithering explained.

    What he said was that dithering operates all the time in Android. In Windows Phone 7 it only operates when you zoom in. That’s why you saw the colours become more simplistic when you zoomed out- dithering had stopped. Obviously with this simpler range of apparent colours (without dithering) you don’t have enough colour steps to create the impression of a smooth colour gradient. Because the colour steps are then more abrupt they are more noticeable, and you see colour banding where you have a colour gradient (for example in a picture of a sunset).

  • BucksterMcgee

    First of all, my poor explanation skills aside, not to annoy you, but perhaps you could have read my post more carefully. My edit was nothing more than an observation that I had noticed long before this post, with the additon of my assumption that it and the color banding are related. If the issue is that it’s truely 16bit, and the “loss” of high contrast is due to turning on and off dithering, then my assumption is correct, and there is nothing to write home about. Furthermore, I know exactly what DITHERING is, and the difference between color depth, but THANK YOU for pointing it out anyway.
    Secondly, I don’t care how the issue is fixed, whether by adjusting the use of dithering in the OS or by fixing the real issue and moving to 24bit (if that is infact the true problem), I just want it fixed. Obivously 24bit would be the perferred choice, but I’m going to have to make another assumption that if they didn’t use it, there was a reason for that. For that reason, again I am less concerned by the means, and more concerned about the result of reducing this problem.
    As a last part, as you seem so incredibly knowledgeable in this mystical world of technology, I will ask a genuine question. Could adjusting the OS’s use of dithering help with images within app? Such as load screens, etc? Or do those developers just have to be more cautious and thoughtful of what images they have?

  • Anon

    I explained dithering and colour depth just in case, I had no way of knowing your level of knowledge. I was picking up on your final comment: “I assume this and the color banding issue are connected in some way, as zooming in seems to fix the color bandind as well.” I don’t understand why you said “I assume”. The reason I don’t understand is that the article is explaining THAT THEY ARE CONNECTED, and EXACTLY WHAT WAY the author thinks they are connected AND WHY ZOOMING IN FIXES BOTH BANDING AND BRINGS MORE SUBTLTY TO COLOUR – because dithering will naturally do both things. So having read the article I thought you saying “they seem connected in some way” seemed a rather odd thing to say. The “some way” is dithering, and the article explains that.

    You talk about a “loss of high contrast”. It sounds to me that what you may have seen was not the loss of high contrast, but the gain of artificial contrast when colours that were really very dark grey were approximated to black.

    The answer to your last question depends on how much freedom the OS allows app developers in their use of dithering. I do remember reading a post by a developer, about this same issue, along the lines of “oh dear, developing for lots of different hardware throws up a surprising number of issues, we found this with Android, we may well need to avoid the use of smooth colour gradients”. I just tried to find the post so I could give a link, but I can’t remember where I saw it. I would think the use of dithering or higher bit depth increases the required processing power.

  • Anon

    Edit: to above, I meant to say your losing artificially high contrast, “fake” contrast if you like.

    I didn’t understand why you talk about “my assumption that this and colour banding are related”. In the context of the article, it is the authors assumption wouldn’t you say? Perhaps you meant to say “when I thought about this issue before reading the article, I came to the conclusion that zooming in fixed both banding and brought more colour subtlety. I now see the authors suggestion that both are caused by dithering being switched on as you zoom in”.

  • Anon

    To be honest with you, I have made a meal of this. There is still something about your original post that strongly makes me think you can’t possibly have really got his point about dithering. But you probably do now, and anyway I wish I could just delete all my posts and start again. But I can’t unfortunately. Sorry.

  • http://www.mobiletechworld.com MobileTechWorld

    Hi there guys,

    Both of you have it right so don’t sweat it ;)

    To be clear:
    - Dithering in the Android browser is only triggered when the page is not moving (when you scroll/pan the images embedded in websites look as crappy on the Galaxy S as on the Omnia 7)
    - Video playback is identical on android and WP7
    - There’s no dithering at all in IE Mobile in WP7
    - In the WP7 picture viewer dithering is enabled once you start zooming in a pictures (you will principally notice that the pictures suddenly gets brighter)
    - In Android the picture viwer (CoolPix)applies dithereing even when pics are not zoomed -in
    - It’s the same on Android. AFAIK the OS is rendered in 16bit but some apps (like picture viewers have dithering enabled)
    - AFAIK Android also renders the OS’s UI in 16bit
    - The Super AMOLED panels are 24bit displays (similar to the IPS panels in the Moto Droids and iPhone 4, previous iPhones had 18bit screens)
    - Super AMOLED panels are RGBG (Red Green Blue Green) so they have nearly twice the amount of Green sub pixels as a normal RGB panel..hence the severe banding issue (the super high contrast also aggravates the issue) compared to regular RGB screens.
    - 16bit is usually used to minimized bandwidth and video memory usage

    All in all it’s kind of a mess. Ideally everything should be rendered in 24/32bit but I don’t think MS will do this.

  • Anon

    I read a review of a small LG OLED TV and the reviewer praised the picture quality very highly. A small amount of banding was visible before calibration and none to speak of afterwards. I don’t know if it used RGB or Pentile RGBG. Is it necessary to use the Pentile Matrix, or is that just Samsung’s choice?
    If it’s not necessary, do you think someone will soon deliver OLED screens with RGB 3 sub-pixels per pixel, seriously reducing all the problems above? Why have Samsung gone with the Pentile Matrix?

  • http://www.mobiletechworld.com MobileTechWorld

    Yes only Samsung’s AMOLED and Super AMOLED panels use the RGBG PenTile Matrix 5Samsung bough the company that developed this tech 2 years ago) other AMOLED panels from LG and Sony have regular RGB matrices I IIRC. Interestingly They are also heavily developing new LCD based panels with their own PLS tech (Plane to Line Switching) to compete with LG’s IPS panels (In Plane Switching) and Sony’s SLCD. So AMOLED isn’t really the only high tech we are going to see in future phones (even-though there’s Super AMOLED 2 panel rumored to be introduced in February nd Samsung new AMOLED Fab plant should also go online early next year). It’s kind of a big mess thought..

  • http://twitter.com/moonmantweets moonman

    It’s the browser. Outside IE pictures look fine, even those you saved from IE.