Why my AMOLED has pinkish tint (Answer inside) - UPDATED

Hi,

Ok first of all i know that there are other threads related to this thing, those threads defined the problem and many posts were speculations and wondering wither its hardware/software/glitch .... etc

As i was searching about this and saw the other members conclusions I wanted to start a new thread so any new member comes and read this and know exactly why is this happening to him/her, and wither its a real problem or not.

Desire's AMOLED displays have a big resolution 480*800 pixels,and have different sub-pixels arrangement in it, each pixel have "RedGreen" and the one after it is "BlueGreen" .... RG BG RG BG, .. etc, that is PenTile Matrix, while other LCD and "normal" displays have RGB RGB RGB, ... etc
for more info about this, click here
the pentile matrix looks exactly like this

Now the effect of this matrix is double edged, instead of having 3 sub-pixels in each pixel, we have 2 sub-pixels in each pixel, this saves power, precious battery power, but also this arrangement of sub pixels contributes to the issue somehow because the colors will not "look" exactly the way they are (the way the RGB matrix show it, which is used in most of our displays like TV, PC, LAPTOP, ... etc), there will be slight difference due to the screen "approximation", and that difference is NOT noticeable in most cases, only in few cases where the solid colors intersects with each other.

see the posted screenshot of Gmail app with the gradient color near it

see how the color picker identified the gray color, .. and how close it is to the pink, the pink showed due to the display approximation of the color.

and most importantly see how "photohop" saw the color as "not a web safe color" and see how it showed in the small square the pink color!

photoshop detects this because it knows that if an "approximation" happens than this will be displayed as pink.

And not only that, photoshop suggests that you put a "safe" color, and it shows "pink" instead of the gray as a suggestion!! why is that?

To find the answer, look at the circle in the color gradient board, you will see that this "gray" is nearer to the pink than it is to the actual gray!!!

and here we are seeing it pink on the Desire's AMOLED devices, what a surprise!

Now notice how the upper bar is dead gray, and does not have any pink in it, that is because its "GRAY" is not close or near any other visually-different color. and of course photoshop identified it as "SAFE for web", and that even if an approximation happens, this will still be rendered as gray

the good news is, it will NOT be noticeable in most of the cases, because most of the colors are not gray scaled and not "visually close to the human eye" to other colors, as you can see from the gradient color posted there are many "safe" grays out there, ... but google had to choose that gray that is near the pink

Now the bad news is, that this is NOT an android software problem, it is a hardware (display/calibration) issue.

but does that mean it cannot be solved "indirectly" by software? .... not sure, am thinking of what if Android created a layer where it picks each color and see wither its safe or not, .. if its not safe than do an OS approximation for that color, if its "gray near pink" change it to "gray" and pass it to the AMOLED as "safe color". not sure how that would be implemented or what is the weight and impact.

but as i mentioned before, if apps stick to "safe" colors, this will insure that even if an approximation happened, nothing will be noticeable

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UPDATE For people who think that the issue is from the browser and not from the AMOLED display that has PenTile matrix.



here is a screenshot from Android SDK emulator with the same browser as in Desire (WebKit)

here is a screen shot of the original website from the PC, using Google Chrome browser

and here is a screenshot of the site taken directly from HTC Desire (the site has been visited from the HTC Desire and a screenshot was taken and transfered)

Its pretty clear that the browser is not the real issue (even though it has some slight very slight pinkish hue), the pinkish is alot worst in the desire than what is the emulator and the screenshots show
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UPDATE
After seeing the below pictures (thanx onkolog for posting those pics!), one can conclude that this "gray shades to strong pinkishness" issue is definitly not a general AMOLED issue.

People reported that in Samsung Galaxy, and Legend (Both AMOLED but not PenTile matrix) have slight pink viewing the htc.com site, but it is nowhere as pink as found in the HTC Desire

HTC Desire:

HTC Legend

as the pictures shows clearly that the legend (which has AMOLED display with normal RGB implementation) shows the Gray as pretty Gray (not as pink as the Desire).

here is a pic of the Desire & Legend side-by-side with the HTC website shown
(thank you ohyeahar for this shoot). the Desire has more pinkishness than the legend, the legend seems fine but some people said that it also has some slight pink (not as desire though)

as you can from the photo and as ohyeahar stated (having both devices, legend and desire) that its not a real issue, but its there if you really look for troubles you will find it, otherwise normally you wouldnt be annoyed from it


EDIT: some people have pink hue all over the screen, not only particular apps/colors, .. IMO this just your device, and you should replace your device

EDIT: I used web-safe colours as a technique to show how the colours might look different due to screen approximation the web-safe colours is not designed to detect the approximation of the Desire's AMOLED accurately, it is designed for web approximation due to compression, but they are similar some how, in terms of that colours are getting approximated and changed sometimes to the nearest possible colour thats why i used it.

the "web-safe" approximation only appears when an image is compressed for web standards (or approximated in case of the Desire's AMOLED), .. some images are not compressed for web use, you see the the HTC.com page gray on your monitor, and i see it gray on my nokia e75, but it looks pink in the Desire's AMOLED because the display of the desire (and i suspect android too) approximate the colour, and i used the web-safe colour technique to detect that (even though that this technique is not dedicated to identify the Desire's AMOLED approximation)

The battery drain from the screen is somewhat dependant on what you are watching. If you are displaying an image with lots of different colors, areas with black and so on, the screen will not use as much power as an LCD-screen. But if you for instance use a spreadsheat in excel or word-doc. where most of the screen is bright white, then the screen will use more power than an LCD, since it has to light up all pixels, whereas the LCD only has a few backlights.

As an exampel from a QVGA screen; black text on a white background would eat up 3W, white text on a black background would only use 0,7W.

So in real life, there might not be that much gain in powersaving.

The display colours are as they are due to display RGB primary calibration at the factory - and software to a much much tinier degree - nothing to do with manufacturing. It is either intentional to circumvent other problems or simply poor-to-no calibration. The DDI approximation won't by itself make such errors with proper display calibration.

1. The Desire and Nexus One both have a very blue colour temperature intentionally, which shifts the greys to the red-magenta spectrum when combined with the PenTile over-green subpixel approximations the DDI must provide for. The reason for that starts with the fact that the organic B element in OLEDs fail far faster than the RG, and the blue luminance is very low but with high power draw which results in very low blue luminous efficiency right from the start. This is a known problem with OLED engineering. To delay the onset of the B spectra output decreasing to the viewer, manufacturers intentionally shift the beginning calibration towards very blue output. So it starts off with colour oversaturation and a bluey temperature with higher power draw, but as the B pixels degrade and their luminosity decreases, the blue doesn't suddenly disappear within the first 2-5 years of average use, it will just decrease significantly. As the blue luminance decreases, at some point, the colours will appear far better than when new.

You can see such measurements in these tests by professionals, for instance: http://www.displaymate.com/Nexus_One_ShootOut.htm

2. There are other workarounds employed, like the PenTile matrix, but it shouldn't affect the image reproduction much if the display is properly factory calibrated with the primaries and the software algorithms are decent with scaling and compression. Higher B spectra than with PenTile would increase sharpness but also increase power by a large margin on these displays too. Increasing B spectra would also increase the probability of defective subpixels on the display.

3. The bad readability people complain about in sunlight is due to very low maximal white luminance with these OLED displays (~200*cd/m2) and the high reflectance on these displays (primarily because of the metallic cathode, large spaces between layers so the panel is far down and poor anti-reflective coating on-screen). The device manufacturers can easily circumvent these, with additional time+cost.

4. If colour accuracy is what you are after, except black, nothing on the market touches the LCD featuring Droid X and the Droid - both known for absolutely excellent colour reproduction. I've used both. Look at the Droid here, for instance: http://www.displaymate.com/Motorola_Droid_ShootOut.htm

5. Just to be clear. I have absolutely no problem with some bits currently appearing slightly pink instead of light grey. Had someone here not complained, I wouldn't have noticed. I do dislike the obvious oversaturation in colours everywhere much though.

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- Sent via my HTC Desire -

打攪了，我是進來賺積分的。：d