For purpose of understanding imagine two 4" screens both with 800x480 pixels resolution:
One is RGB, the other is Pentile GRGB.
So, the area of each pixel in each screen is the same, I name it 1 unit-pixel. It happens that this unit-pixel in the RGB screen has 1/3 of area in green (sub-pixel), 1/3 of area in red and 1/3 of area in blue; In Pentile this unit-pixel has 1/3 of area in green and 2/3 of area in red (double area of red); next pixel has 1/3 of area in green and 2/3 in blue (double area of blue).
Imagine now one figure with 100 pixels represented in these two screens; imagine now this figure is color green: the number of sub-pixels green is exactly the same in RGB screen as Pentile screen, this is 100 sub-pixels, and also the same in area of green.
Imagine now the figure is color red: the number of red sub-pixels in RGB is the same as it was in the green color, this is 100 sub-pixels, but in Pentile the number of red sub-pixels is half of green, this is 50 sub-pixels; however the area of red is exactly the same as it was in green.
The same happens in blue color figure.
Saying this I guess everybody understands that in a given picture, the area of green, red and blue is exactly the same in both types of screen. It doesn't matter if screen is RGB or Pentile; the area of colored sub-pixels is exactly the same in both types.
As in red color, in Pentile screen, is one unit-pixel switch on and next unit-pixel is off, and so on, (but each one with the double in area), if the resolution is a little small like 800x480 in 4" screen, indeed, we yet will be able to see black unit-pixel in the middle of each two red pixels (never forget that color area in each color, is the same as RGB).
However this effect is reduced (not completely eliminated) because in the next line the red pixel is advanced of one unit-pixel (alternated), as Pentile in sub-pixels red/blue and lines use alternate technique.
Increasing resolution to 1280x720 in 5" screen, the unit-pixels will be so small that we will not be able to see the black unit-pixels switched off in the middle of each two unit-pixels.
Furthermore, in real situation, all unit-pixels has the sub-pixels green switched on, this is exactly the same as RGB, and as already said color area is the same.
So, we get exactly the same resolution in both systems as the unit-pixels are the same in both systems and each sub-pixel red or blue have the double in area in Pentile to compensate the half number of these sub-pixels.
Calculations only with sub-pixels, not taking in account the fact that sub-pixels red and blue are double of area in Pentile, conduces to bad and misleading results.
In Galaxy S (1) red/blue sub-pixel area is double than green sub-pixel to compensatd the half number of red/blue sub-pixels.
In Note/Nexus, if the red/blue sub-pixels area is equal to green ones, then the bright of red/blue pixels must be the double of green ones (maintaining the due proportion) in order to maintain the color accuracy as the red/blue number of sub-pixels is half of green. However the resolution maintain equal as RGB because the number of unit-pixels is the same as RGB. So in this case the compensation to equal RGB screen is based in the bright of sub-pixels red/blue instead of double area.
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After a year of usage, through using the antutu test app for LCD I noticed that the pixels on top edge of the screen are brighter than the rest. It's probably because of the black notification bar.
Can other users with super amoled NS check this and see how their panel holded up? The best way to check it is with a plain gray or blue image.
Thanks
neXus S i9020T - AOSP+ - SG Kernel - 100/1320 MHz
I've the i9023 myself, but current (possibly future, too) OLED panels degrade unevenly. Whites and blues use the most power and lower the brightness after prolonged use more so than reds and blacks (with blacks effectively turning off the pixels and draining little to no power and don't effect brightness).
These kinds of effects are likely going to be more prevalent now that some years have passed since the first OLED displays have appeared. For comparison, LCDs use a backlight behind the screen which uses the same amount of power between white and black, though blacks look a little grey. As a result, there is even brightness fade.
I have verified that the AMOLED in Galaxy S4 is indeed a PenTile similar to S, S3, Galaxy Nexus and other brands that uses Samsung PenTile super AMOLED displays. The new S4 AMOLED have green subpixels centered in the middle of each input pixel with red and blue subpixels situated at the bottom.
Total Number of Subpixels:
G: 1920 x 1080 = 2,073,600
R=B = 1920 x 1080 / 2 = 960 x 540 = 1,036,800
Total # of RGB subpixels = 4,147,200
The Green subpixels indeed have full resolution while the Red and Blue subpixels are halved. But this does not interfere the image quality especially the PPI is 441. Since PPI is calculated based on the full pixel density along the diagonal line, it is not accurate to measure display designed for human perception with virtual resolution. Because virtual resolution utilizes less RGB subpixels to construct single pixel width or height black and white lines. It however, works exceptionally well when the lines are narrow enough to be less than our "retina resolution" which is around 0.6 arc-minutes (binary lines). Our eyes, instead, see an averaged of the black and white lines in gray at around 6 inches away from the 5" Full HD display.
The S4 AMOLED renderer intelligently shares the red and blue subpixels horizontally to achieve a correct overall color.
I have attached an example of how S4 renders the vertical lines. Horizontal lines isn't shown because S4's AMOLED is able to display black and white horizontal lines without sharing the red and blue subpixels.
According to http://www.displaymate.com/Galaxy_S4_ShootOut_1.htm
"The pixels on most current OLED displays have only 2 sub-pixels in each pixel instead of the standard 3 Red, Green, and Blue sub-pixels found in most other displays and display technologies. Half of the PenTile pixels have Green and Red sub-pixels and the other half have Green and Blue sub-pixels, so Red and Blue are always shared by two adjacent pixels....
here are 312 Red and Blue Sub-Pixels Per Inch"
We know that Green subpixels has full resolution 1920 x 1080 at 5 inches with 441 SPPI. If the number of subpixels of Red/Blue is half that of the green subpixels, why is it 312 SPPI and not 220 SPPI?
G = sqrt(1920^2 + 1080^2)/5 = 441 SPPI
R = B = sqrt((1920/2)^2 + (1080/2)^2)/5 inches = 220 SPPI
I've had 3 s6 edge plus now the 1st one appeared to have a great screen but i didn't check properly the second had a terrible screen with the green pixels on the default background in a circular motion and the third has less of it but on bottom right on purple background the pixels colour is not uniform some seems lighter or darker than others. Is this just the nature of amoled screens that each pixel is different that you won't get a perfect screen where all the pixels under a green or purple background are even?
On full black or white it seems ok i just noticed such differences in screen quality between the devices. Is getting a near perfect screen with all pixels the same colour ie not faded or darker impossible?
I should have kept the first one cos its screen was good it was manufactured in august whereas the next 2 i got were part of same assembly batch made on same day 13/10/2015.
I just got fed up in the end as i ordered online and had to wait for replacements to be sent.
Do any of you have these screen issues on the default background of green if you look on bottom half of screen left side there seems to be this weird circular heat pattern of lighter pixels some dimmer than others. On a purple screen background the bottom right there purple is not even. I know that's not right but is it very difficult getting an amoled screen which is near perfect?
Im not sure if this is a sign my pixels are fading or wearing out or it is screen burn in the factory but samsung quality control is abysmal they let through any screen in hope the average consumer wont pay attention to uneven screen.
Is it normal to have a amoled screen like this?
As in imperfect colours pixel degrading out of the box. The purple walkpaper top left i can see that it's not all one colour and some of the pixels look faded is this standard and luck of the draw getting a good screen?
I have not done a screen test in fear of how bad it might look but on black screens and all white it looks good it's just the wall papers i can see splooges of uneven colour how bad or good is every one elses screen?
I think i notice it more because i came from an s4 so bigger screen equals more noticeable imperfections.
I didnt test my original one properly but it's screen seemed really good on the default wallpaper i duno what it woulda shown on purple.
Is this screen burn or just faded pixels from over testing out the box?
Why is it so f'ing difficult trying to get a perfect samsung screen? ??
Recently I switched to Evolution X custom rom on my Galaxy A205F. It works amazing, there are no problems with optimisations.
But the text and some things are too bright. I play Battle Royale games and the health bar got burnt into the screen.
Is there any fix for this like OneUi had? So that this doesn't happen at other parts of the screen.
Keep brightness at 50% or less.
Avoid using in direct sunlight*.
OLEDs have a limited lifespan.
Less brightness/time on means a longer lifespan.
Blues OLEDs have the shortest lifespans while the lower wavelength energy reds the longest. Any type of blue LED or OLED have notorious shorter lifespans than their lower light energy red counterparts.
However to generate the color white the blue pixels operate at a higher output in comparison to other colors.
So white produces the most overall damage as well the most damage to the blue pixels.
Limit the length of time the same static image is present especially whites and blues.
Use dark mode and darker wallpapers, minimalist icons packs with more red and less whites/blues.
Get rid of perpetually displayed icons on the header bar; use a pull down style if possible.
Rotate the position of widgets and icons occasionally if possible.
*it's not just the OLED semiconductors in the display but thousands of semiconductor that drive them. All can be damaged by excessive temperatures and their heat sinking capacity is limited. A display operating at full brightness in direct sunlight on a hot running device can damage a display.